BULLETIN 516 AGRICULTURAL EXPERIMENT STATION R. DENNIS ROUSE, DIRECTOR NOVEMBER 1979 AUBURN UNIVERSITY AUBURN, ALABAMA y iuAjR f I CONTENTS ACKNOWLEDGMENT ............................. INTRODUCTION ... .............................. M ATERIALS AND METHODS ................................. .......... .......... Page 2 3 6 6 6 7 7 7 7 19 ...... Baseline Data .................................. Planting and Sampling .............................. Sample Preparation ................................ Determining Harvest Dates by AMI .................. RESULTS AND DISCUSSION ...................... Maturity Test Plots ................................. Participating Growers ............................... CURRENT STATUS OF THE AMI AND OTHER METHODS LITERATURE CITEp ... ................... FOR DETERMINING PEANUT MATURITY AND HARVEST DATES ............ 21 22 I ......................................... APPENDIX II ....................................... ............ APPENDIX III ........................... ........................ APPENDIX IV ................. APPENDIX APPENDIX V.......................................27 24 25 25 26 ............. APPENDIX VI ........................... ....................... APPENDIX VII ................ APPENDIX VIII....................................30 APPENDIX 28 29 31 IX .......................... ............. FIRST PRINTING 3M, NOVEMBER 1979 ACKNOWLEDGMENT The contributions of J. G. Starling and H. W. Ivey, II, Superintendent and Associate Superintendent, respectively, Wiregrass Substation, D. L. Hartzog, Agronomist-peanuts, Agricultural Experiment Station-Cooperative Extension Service, and laboratory assistants, William Buie, Charles Chapman, Susan Corcoran, and Larry Savelle, are gratefully acknowledged. The authors express appreciation to the Alabama peanut growers who participated in this study and to Dr. Gale Buchanan, Department of Agronomy and Soils, and Drs. Rodrigo Rodriguez-Kabana and Paul Backman, Department of Botany and Microbiology, for allowing us to take samples from their experimental plots at the Wiregrass Substation. This research was supported by funds from the Alabama Peanut Producers Association and Auburn University Agricultural Experiment Station. Information contained herein is available to all persons regardless of race, color, or national origin. Determining Peanut Harvest Dates in Alabama by the Arginine Maturity Index (AMI) 1 J. D. WEETE, W. D. BRANCH, and T. A. McARDLE 2 A INTRODUCTION L VERAGE PEANUT YIELDS in Alabama have increased steadil over the past 20 years, from approximately 1,100 pounds p( acre to 2,700 pounds per acre (1). This progress in peant production has been due primarily to improved varieties an cultural practices, such as pest control measures (fungi, it sects, nematodes), crop rotation, irrigation, and weed contro Although there are some climatic and soil factors that ma limit peanut production in this State, the potential averag yield of peanuts is not known and has certainly not bee reached. This is illustrated by the fact that some Alabam growers consistently produce 4,000 to 4,500 pounds per acr and this level is routinely obtained under controlled cond tions at the Agricultural Experiment Station's Wiregrass Sul station, Headland, Alabama. One of the most important problems in peanut farming i deciding when to harvest because pods of cultivated peant plants do not mature at the same time. If peanuts are harveste, too late, many pods detach from the pegs and remain in th soil; if harvested too early, the abundance of immature see, would be too high for the desired optimum yield and grad( Consequently, variable proportions of mature and immatur 'Mention of firm names or trade products does not imply that they are endorsed < recommended by Auburn University over other firms or similar products not mei tioned. 2 Respectively, Associate Professor, Research Associate, and Research Associat Department of Botany,Plant Pathology, and Microbiology. ALABAMA AGRICULTURAL EXPERIMENT STATION seeds are obtained when the crop is harvested any time after fruit set, making the time of harvest a critical factor in obtaining high yield, grade, and price return. Traditional methods for determining optimum peanut maturity and harvest time are subjective and generally unreliable. The number of days from planting, degree of darkening on the inside of the pod, certain seed and plant characteristics, and environmental conditions are often used as criteria for deciding when to harvest peanuts (2, 3, 7, 9, 10, 14, 17, 19,20, 21). One of the most popular subjective means of determining peanut harvest dates is called the shellout technique (7, 9, 11, 17). Determining harvest dates by this method requires the removal of all pods from several plants collected from different areas in a field. The pods are then opened and classified according to maturity based on the degree of darkening inside the hull and the color of the testa, Appendix I. Peanuts of the Florunner variety are considered mature and ready for harvest when approximately 60 percent of the pods are dark inside the hull, or when 70 percent of the seed show a deep pink color (3, 4, 7). During the past several years there has been considerable interest in developing objective methods of determining maximum peanut maturity so that more accurate estimates of harvest dates can be made. It was recently shown that there is an inverse relation between peanut seed free arginine (amino acid) content' and maturity (8, 25). An automated method of determining the arginine content of peanuts and forecasting harvest dates was subsequently developed (24). This method is based on the change in the ratio of free arginine to dry matter content of peanut pods during development and is called the Arginine Maturity index (AMI). This ratio progressively decreases during pod development until a minimum value is reached. The time at which the AMI value of a representative sample from a particular field reaches a minimum is correlated with a high proportion of mature peanuts and time of harvest. A graph of AMI values taken during pod development over a period of several years, figure 1, can be used to estimate harvest dates from AMI data taken in subsequent years. This is possible because the pattern of pod development, and hence the change in AMI values, is similar from year to year unless altered by unusual environmental conditions. DETERMINING PEANUT HARVEST DATES BY AMI 5 AMI 200 150 50 0 35 28 21 14 7 0 -7 Days to harvest FIG. 1. Relation between AMI values of developing peanuts and time of harvest is shown by the dotted line. Solid lines represent standard deviation. (Georgia data supplied by Dr. Clyde T. Young.) 6 ALABAMA AGRICULTURAL EXPERIMENT STATION In 1976, a 2-year study was initiated to test the AMI method in Alabama. The results of this study were obtained from experimental plots at the Wiregrass Substation and from fields of participating Alabama peanut growers and are summarized in this publication. MATERIALS AND METHODS Baseline Data Determining peanut harvest dates by the AMI method is based on known and predictable changes in AMI values during pod development that were established for peanuts of the same variety during previous years. To establish this baseline data, three to four representative pod samples are taken from a field of less than 30 acres, analyzed separately, and the AMI values averaged to obtain a figure representing the maturity condition for the field at the particular sampling date. The sampling procedure is initiated approximately 120 days after planting (5 to 6 weeks prior to an estimated harvest date) and is continued at weekly intervals until a week after optimum maturity. The AMI values are plotted against days to harvest to obtain the AMI curve, figure 1, and the lowest point on the curve represents optimum maturity. Because of the general reproducibility of this curve from year to year, it can be used to determine peanut harvest dates in subsequent years with averaged AMI values from only three to five samplings per field taken between 2 and 4 weeks prior to an estimated harvest date. Planting and Sampling Each year of this study, samples were taken for AMI analyses between about August 1 and September 30, or about 101 to 122 days after planting (DAP). During this time, a temporary laboratory was established at the Wiregrass Substation. Since Florunner is the principal peanut cultivar grown in Alabama, it was the only one tested in this study. Baseline data developed in this study were taken from peanuts grown on maturity test plots at the Wiregrass Substation differing only by planting date and crop (corn or peanuts) planted the previous year. Beginning April 7 and 15, peanuts were planted at about 1-week intervals resulting in five and four planting dates DETERMINING PEANUT HARVEST DATES BY AMI (plots) per field in 1976 and 1977, respectively. In 1976, the maturity plots were in a field planted to corn the previous year; and in 1977, two sets of maturity plots were used, one planted to corn and the other to peanuts the previous year. Irrigation was used only in 1976 and standard practices were used each year for the control of leafspot and insects. Samples were also taken from irrigation test plots at the Substation. In addition, samples were taken from fields of participating growers in 10 counties in 1976 and 5 in 1977. Sample Preparation Pods for each sample sufficient to fill a quart container, regardless of size, were picked by hand. The pods were then washed with water and prepared for analysis. Laboratory procedures for sample preparation and analytical methods were previously described by Young (24). Determining Harvest Dates by AMI AMI data used for determining harvest dates in this study were supplied by Dr. Clyde T. Young and were taken from peanuts grown in Georgia. RESULTS AND DISCUSSION Maturity Test Plots Although recommended planting of peanuts in Alabama is between April 1 and 20, the average planting date is about May 1 (3). Early April planting permits a longer growing season, with the pod development stage occurring at the peak of the summer rainfall period beginning in late June (4). In each year of this study, peanuts were planted at 1-week intervals for 5 weeks beginning April 7 to include the range of planting dates commonly used by Alabama growers. AMI values of peanuts from the maturity plots followed the expected declining and leveling off pattern with pod development and maturity, figure 2. In 1976, for example, the pattern was similar regardless of planting date. The number of days from planting to optimum maturity differed according to planting date; later planting dates resulted in correspondingly shorter intervals between planting 8 AMI ALABAMA AGRICULTURAL EXPERIMENT STATION 250F f PLOT L 200 - 150 PLOT III /-PLOT 11 PLOTS loot- L- I ) ii ~ :IL0116 IC zTIII I( M I16 121 136 131126 11 18 9 12 141 12 146 151 156 6 17117 8 9 1041 143414 161615 131 136 141 4 6 14 o £Z f6 91 96 101 106 116 Days after planting III 121 126 7-31 8-4 8-9 8-14 8-19 8-24 8-29 9-3 Sampling date 9-8 9-13 9-18 9-23 9-28 AMI values as a function of number of days from planting, for peanuts from FIG. the maturity plots in 1976. Highest yield for each plot is indicated on the abscissa. 2.- DETERMINING PEANUT HARVEST DATES BY AMI TABLE 1. SUMMARY OF RESULTS-FOR MATURITY PLOTS, 1976 2 1 9 Test plot (planting date) I (4-7-76) .............. Harvest date 9- 1-76 9-13-76* 9-17-76 9- 1-76 9-13-76* 9-13-76* 9-17-76 Days from planting to harvest 147 159 163 140 152 145 149 Yield , lb./acre 3,127 3,422 2,812 3,194 3,557 3,011 - Pct. TSMK3 77 73 - 11 (4-14-76) III (4-21-76) .............. ........... ... 75 75 - IV (4-28-76) .......... V (5-5-76) .............. 9-13-76 9-17-76* 9-17-76* 9-20-76 138 142 134 137 2,878 3,594 3,572 3,422 74 73 74 69 'Dates marked with an asterisk are those closest to the AMI predicted date. 2Unless otherwise specified, yield values are the mean of three replications. 3Percent total sound mature kernels. Each value is based on the average of three to five samples. and optimum maturity, table 1. This supports the recognized fact that later planting dates result in a faster rate of peanut maturity and discounts the number of days from harvest as a reasonable method for determining time of harvest. Although planting dates were staggered at 7-day intervals, there was only a 4-day difference in reaching optimum maturity between plots planted 29 days apart (plots I and V). However, it should be taken into account that the five adjacent plots collectively represented a single field that experienced common environmental conditions. The relation between planting and harvest dates would not necessarily be expected to hold true for fields at different locations planted at the same time. Similar results were obtained in 1977. Peanut yields in Alabama during the period of this study (1976 and 1977) averaged about 2,600 pounds per acre. However, yields of peanuts grown at the Wiregrass Substation annually fall in the range from 3,500 to 4,500 pounds per acre, with individual plots sometimes reaching 5,800 pounds (personal communication, J: G. Starling). Except for plot I in 1976, where three samples were taken, samples for yield determinations were taken from each of the remaining plots on two dates. Because of the small number of yield determinations from these plots, it is not certain that the highest yields were the maximum that could have been obtained if harvests had been made at other times. However, the highest yields (3,572 to 4,109 pounds per acre) fall within the range of those 10 ALABAMA AGRICULTURAL EXPERIMENT STATION for peanuts grown at the Substation and are considered to be at least near optimum, table 1. Regardless of whether these yields are optimum, sampling dates resulting in the highest yields were near those dates determined by the AMI method in four of the five plots compared to peanuts sampled at another time. Percent total sound mature kernels (TSMK) wa also higher for peanuts sampled nearest the AMI date from tw of the five plots, with no determination made for the other two compared to plots sampled at another time, table 1. For the data of figure 2 (listed in Appendix II) to be of future use in determining peanut maturity and harvest dates, it mus be related to time to maturity rather than from planting. This relationship was established, taking into consideration the known correlation between low AMI values and optimun maturity (6) and the date highest yields were obtained in tl, maturity plots. These plots were sampled at 2- to 8-day inte vals over a period of 6 weeks and AMI values for the peanui were arranged according to days to maturity, Appendix II When the AMI values for each level of maturity in each plot were averaged and graphed, figure 2, a pattern similar to tha obtained for peanuts grown in Georgia (24, 26), figure 1, wa obtained. Experiments at the maturity test plots were repeated i 1977, but with modifications. For example, three to four san plings for yield determinations were made for each plot. Also one sampling date was selected according to the AMI metho( another according to the shellout technique, and a third at date estimated to be 1 week prior to optimum maturity according to the AMI method. Peanut maturity in these plots (conr peanuts rotation) was reached 2 to 3 weeks later than in 1976 tables 1 and 2. This was attributed to a drought period occu ring in the early months (April through July) of the 197 peanut growing season. However, postpegging rainfall w, 5.77 and 7.62 inches in August and September, respective compared to a 14-year average of 5.77 and 3.37 inches at tl Wiregrass Substation. In spite of the severe early drought in 1977, overall be average peanut yields for the maturity plots were highe (4,473+316 pounds per acre) than in 1976 when there was late drought (3,665±304). The average yield (4,413±413) an, price return from peanuts from plots harvested according t the AMI procedure were significantly higher than for peanut DETERMINING PEANUT HARVEST DATES BY AMI TABLE 2. 11 YIELD, GRADE, AND PRICE RETURN FOR PEANUTS FROM MATURITY PLOTS AT THE WIREGRASS SUBSTATION, 19771,2 Test plots (planting date) Following corn: Plot I(4-15-77) Plot III (4-21-77) Plot IV (4-27-77) Plot V (5-3-77) Type of harvest early AMI shellout early AMI shellout early AMI shellout early AMI shellout Days from Type of Digging planting 3 digging date to digging H M M H M M H M M H M M 9-26 10-4 10-4 9-27 10-4 10-4 9-27 10-4 10-10 9-27 10-4 10-10 164 172 172 159 166 166 153 160 166 147 154 160 Yield, Grade, Return, pet. $/ lb./ acre TSMK acre 4,311 4,311 4,311 4,401 4,492 4,492 4,175 4,538 4,265 4,265 4,901 4,447 68 69 69 68 70 70 704 68 72 71 69 71 903 913 913 925 965 965 8974 947 936 926 1,038 966 738. 9-27 165 3,585 67 early H AMI M 10-4 172 3,630 68 760 69 824 9-30 168 3,902 shellout M 73 954 M 9-12 144 4,2475 Plot III (4-21-77) early AMI-1 M 9-22 153 3,494 70 755 AMI-2 M 9-30 162 4,038 72 889 4,2475 73 954 shellout M 9-12 144 early M 9-12 138 4,0295 71 886 J Plot IV (4-27-77) 9-19 145 4,429 69 954 AMI-1 H AMI-2 M 9-30 156 4,628 71 1,008 4,0295 71 886 M 9-12 138 shellout 139 3,2675 64 652 early H 9-19 .Plot V (5-3-77) AMI H 9-26 146 4,764 68 1,001 shellout M 9-30 150 4,084 71 890 (C Each value represents an average of three samples per type of harvest. 2 3 Plot I was not part of the maturity plots in 1977. Dug by hand (H) or machine (M). 4Percent damage, foreign material, and sound splits were not deducted in the walculations. 5 Values based on one sample. o:llowing peanuts: Plot 11(4-15-77) harvested early (1 week prior to the AMI forecasted date), but Mhere was no statistically significant difference between the rmrly harvested peanuts (4,035±+400 pounds per acre) and harvested according to the shellout technique 4,222+204 pounds), table 3. Although peanut yields from six o eight maturity plots harvested according to the AMI method were higher than those harvested according to the shellout :pchnique, there was no significant difference in high yield for peanuts harvested by the two methods, table 3. This is consistent with a previous report that showed a 0.96 o rrelation coefficient for maturity estimates of peanuts harjested by the AMI and shellout methods (5). ,!lose .verages 12 ALABAMA AGRICULTURAL EXPERIMENT STATION TABLE 3. SUMMARY OF YIELD, GRADE, AND PRICE RETURN FOR THREE TYPES OF HARVEST ON MATURITY PLOTS, WIREGRASS SUBSTATION, 1977 1,2 Type of Yield, Grade, Return, harvest lb./acre pet. TSMK $/acre Early ........................... 4,035a 69a 860a 3 AMI .......................... 4,413b 69a 940b Shellout ..................... 4,222ab 71b 917ab 1 The eight planting dates were used as replications in the statistical analysis. 2 Values within columns with a common letter are not different at the 0.05 significance level according to Duncan's New Multiple-Range Test. 3 The second AMI harvest was used for the following plots: Planting dates 2 and 3 following peanuts. Although the yields for peanuts from the maturity plots were higher in 1977 than in 1976, the reverse was true for percent TSMK. The average high grade for peanuts for plots in 1976 was 75.3+ 1.3 percent TSMK and in 1977 was 69.6+1.7 percent TSMK. In 1977 there was no difference in TSMK for peanuts harvested early and according to the AMI method, but the percentage was significantly higher for peanuts harvested according to the shellout technique, table 3. The price return (dollar value per acre) for AMI harvested peanuts was higher than that for peanuts harvested early, but not for those harvested by the shellout technique. Classification data for two sampling dates according to the shellout technique are given in Appendix IV. Planting peanuts in a field where peanuts were grown the previous year is not recommended because the populations of peanut pests will be higher than if the field had been previously planted to another crop (22, 23). In Alabama, peanuts are most often alternated with corn in a crop rotation program although a peanut-peanut program is common. It is generally believed by farmers that peanuts following peanuts mature earlier than peanuts following another crop. For these reasons, two fields were subdivided into plots differing by planting date and used as maturity test plots in 1977, one planted the previous year to corn and the other to peanuts. There appeared to be little difference in the rate of maturity in peanuts planted in the two fields at the early date (April 15), but the later planted peanuts appeared to mature about 2 weeks sooner when planted behind peanuts, table 2. Similar results were obtained for other fields at the Wiregrass Substation. Higher yields were obtained from fields planted at the later dates. However, higher yields are generally obtained from peanuts planted early (19). In spite of the differences in dates and rates DETERMINING PEANUT HARVEST DATES BY AMI 13 AMI 150 I00 0 3 35 28 7 14 21 Days to harvest 0 -7 FIG. 3. Relation between AMI values and time of harvest for the maturity test plots at the Wiregrass Substation is shown by the dotted line. Solid lines represent standard deviation. 14 ALABAMA AGRICULTURAL EXPERIMENT STATION 14 TABLE 4. ALABAMA AGRICULTURLEPRMN Two MATURITY TEST PLOTS, 19771 TTO SUMMARY OF YIELD, GRADE, AND PRICE RETURN FOR PEANUTS FROM THE Following peanuts Yield, Grade, Return, lb/acre pct. TSMK $/acre 3,902 69 824 4,311 69 913 Plot 11(4-15-77) ... 965 4,2472 73 954 Plot III (4-21-77) .. 4,492 70 4,628 71 1,008 68 947 Plot IV (4-27-77) .. 4,538 1,038 4,764 68 1,001 4,901 69 Plot V (5-3-77) .... 966±52.8 4,385±39 70±2.2 947±85.3 Mean 3 .......... 4,561±247 69±0.8 1Each value represents an average of three samples. 2 Value based on one sample. 3 Means of yield, grade, and price return for peanuts following peanuts and corn are not significantly different according to the student T Test. Test plot (planting date) Yield, lb./acre Following corn Grade, Return, pct. TSMK $/acre of maturity, there were no significant differences in yield, quality, or dollar return for the peanuts from plots previously planted to corn or peanuts, table 4. The ability of the AMI method to provide prior indication of peanut maturity for determining optimum harvest dates was generally good. In some cases, however, considerable judgment based on knowledge of environmental factors and condition of the field was required to reach a final decision on harvest dates. With one exception, optimum harvest dates determined for the five maturity plots in 1976 fell 2 to 3 days short of the date the highest yields were obtained, table 5. The AMI determined date for peanut maturity in plot V, planted May 5, was 10 days short of the highest yield obtained for that plot. However, the harvest date calculated from peanuts taken at later sampling dates (September 8 or 13) was close to the date the highest yield was obtained. In plot V, the peanut yields for samples taken September 17 and 20 were similar, but the percent TSMK (kernel quality) was considerably reduced at the later sampling date, table 1. In 1977, three samplings for yield determination were made, one according to the AMI method. In five of six plots, highest yields were obtained for samplings made according to the AMI method, table 6. In plot II, previously planted to peanuts, the AMI forecast was 4 days over the date optimum maturity was reached. In plots III and IV, also previously planted to peanuts, continuous cropping made interpretations of AMI data difficult. The most accurate dates for peanut maturity were determined with peanut samples taken 3 to 4 weeks prior to harvest, or when the AMI values of these samples ranged from about DETERMINING PEANUT HARVEST DATES BY AMI TABLE 5. FORECASTING HARVEST DATES OF PEANUTS IN THE 1976 MATURITY PLOTS AT THE WIREGRASS SUBSTATION 15 Plot number, date sampled Plot I 8-6 ....... 8-9 ....... 8-16 ..... 8-25 ..... 8-30 ..... 9-8 ....... 9-13 ..... 9-20 ..... Plot II 8-9 ....... 8-16 ..... 8-25 ..... 8-30 ..... 9-8 ....... 9-13 ..... 9-20 ..... Plot III 8-9 ....... 8-16 ..... 8-25 ..... 8-30 ..... 9-8 ....... 9-13 ..... 9-20 ..... Plot IV 8-9 ....... 8-16 ..... 8-25 ..... 8-30 ..... 9-8 ....... 9-13 .... 9-20 ..... Days planting AMI value AMI estimated' days to maturity 29 25 15 18 1 0 10 12 AMI estimated harvest dates 9-4 9-3 8-31 9-12 8-31 9-8 9-23 10-1 Final AMI determined harvest date 9-10 Date highest yield obtained 9-13 121 124 131 140 145 154 159 166 171.3 153.7 106.3 118.4 73.1 68.9 91.6 94.7 117 124 133 138 147 152 159 191.3 154.1 115.2 100.5 98.6 83.7 76.3 34 26 17 14 12 7 4 9-12 9-11 9-11 9-13 9-20 9-20 9-24 9-12 9-13 110 117 126 131 140 145 152 203.5 148.5 148.9 57.6 88.1 65.6 77.5 37 25 25 0 9 3 10 9-15 9-10 9-19 8-30 9-17 9-16 9-30 9-15 9-17 107 110 119 124 133 138 145 208.5 159.2 102.7 97.9 63.3 97.7 67.7 38 27 15 14 0 14 0 9-16 9-12 9-9 9-13 9-8 9-27 9-20 9-14 9-17 Plot V 29 90 169.6 8-9 ....... . 20 129.0 110 8-16 ..... 14 100.0 119 8-25 ..... 7 124 84.8 8-30 ..... 10 92.8 133 9-8 ...... 2 138 73.9 9-13 ..... 16 107.6 145 9-20 ..... 'Values in the column were calculated from using the following relation: Days = 9-17 9-7 9-7 or 9-5 9-17 9-8 9-6 9-18 9-15 10-6 AMI values ranging from 97 to 210 For AMI values below 97, 7 (AMI - 36) 32 estimated days to harvest were determined using the AMI curve. 0) TABLE 6. FORECASTING HARVEST DATES OF PEANUTS IN THE MATURITY PLOTS, 1977 Plot number, date sampled Plot II 9-5.143 9-12.150 9-19.157 9-26..164 Plot III 9-5...................... 9-12.....................143 9-19 Days after AMI value' FP 174.7 135.6 129.4 86.3 -3 - planting FC AMI estiated Dat of AMI M aeo AM2siae 2 forecasted harvest days to maturity FC FP FC FP 27 20 15 8 31 22 15 8 28 21 16 7 19 14 30 21 20 8 10-2 10-2 10-4 10-4 10-6 10-4 10-4 10-4 10-3 10-3 10-5 10-3 Final AMI determined harvest date FC FP 10-4 10-4 Dt ihs ihs Dt yield obtained FC FP 10-4 9-30 159.0 128.7 103.6 87.6 136 150 10-5 10-3 10-9 10-4 - aw 10-4 - ...................... 9-26 ...................... Plot IV 9-5.............129 9-12 ...................... 9-19 ...................... 9-26 ...................... 157 176.9 134.8 102.6 87.2 163.1 131.1 107.5 82.7 10-4 - L5 jc C) C ir 136 143 150 - - 10-4 - 10-4 - Plot V 35 196.5 122.0 122 9-5 ...................... 20 97.9 135.6 129 9-12.................... 17 87.7 112.7 136 9-19 ..................... 9 87.0 90.7 143 9-26.................... 'FC = following corn, FP = following peanuts. 2Estimates made from AMI data supplied by Dr. C. T. Young. 'Continuous cropping occurred in these plots (see text). r 8 10-10 10-2 10-6 10-5 9-24 9-26 9-27 10-4 10-4 9-26 10-4 9-26 x m m __ 8 z -a - -4 0 z DETERMINING PEANUT HARVEST DATES BY AMI 17 100 to 160. A curve developed from AMI data from the maturity plots at the Wiregrass Substation during 1976 and 1977 (Appendix V and VI) is given in Appendix VII. These data support claims that accurate peanut harvest dates can be determined 2 to 3 weeks prior to optimum maturity (24) and is consistent with recent data obtained in Georgia (16). A new method of determining peanut maturity was recently reported, the seed-hull weight ratio method (13). This ratio, obtained by dividing the fresh or air-dried weight of the seeds by the corresponding hull weight, gives the fresh weight seed-hull maturity index (FMI) or dry weight seed-hull maturity index (DMI), respectively. AMI values, which decrease with maturity, were negatively correlated (r = 0.905) with DMI. Values of 2.62 DMI to 2.79 FMI corresponded to maturity according to a rigid physiological maturity classification system (11). FMI and DMI values were determined for peanut pods separated according to the five maturity classifications (for the shellout technique) given in Appendix I. Deciding optimum maturity and time of harvest by the shellout technique requires judgment in making the maturity classification. When 60 to 70 percent of the, pods fall into the mature and intermediate categories the field is considered at optimum maturity and it is time to harvest. The upper FMI and DMI values of 2.72 to 2.83 and 3.87 to 4.17, respectively, correspond to the maturity classifications acceptable for harvest, table 7. There is a large transition in maturity between the large seeded TABLE 7. RELATIONSHIP BETWEEN AMI, FMI, DMI, FRESH AND AIR-DRIED WEIGHT PER SEED, AND MATURITY CLASSIFICATION FOR PEANUTS FROM MATURITY TEST PLOTS, WIREGRASS SUBSTATION, 19771 Maturity classification AMI FMI 2 Fresh weight per seed, gram DMI 2 Air-dried weight per seed gram Small seeded immature ...... 356.3 0.32±0.20 0.20±0.12 0.52±0.24 0.05±0.03 Large seeded immature ...... 202.2 1.46±0.49 0.61±0.16 2.41±0.88 0.28±0.12 Intermediate ..... 44.3 2.73±0.30 0.83±0.08 4.17±0.44 0.52±0.06 Mature - ........ 42.3 2.83±0.39 0.85±0.11 4.13±0.56 0.58±0.07 Mature. ......... 27.2 2.72±0.45 0.79±0.11 3.87±0.58 0.58±0.09 1 Values are averages of six samples taken from the two samplings for the shellout technique (see Appendix IV). 2 Arginine maturity index (AMI); fresh weight seed-hull maturity index (FMI); air-dried weight seed-hull maturity index (DMI). 18 ALABAMA AGRICULTURAL EXPERIMENT STATION immature and intermediate classifications according to the AMI, table 7. In another study, FMI and DMI values of 2.15 and 3.67, respectively, corresponded to the highest yield obtained over several sampling dates and the AMI forecasted date (16). The AMI method was also used to determine harvest dates for experimental plots involving irrigation at the Wiregrass Substation. There were four plots differing by the amount of irrigation water added. In one plot, no irrigation water was added and in the other three 0.7 inch of water was added when the soil tension reached 20, 40, and 60 centibars, respectively (15). Samples were taken for yield determinations from each plot at three dates, one according to the AMI, table 8. Optimum maturity was reached at an earlier date in the plot maintained at a higher moisture level (20 centibars) where the highest yield was obtained. The highest yield obtained in this plot was with the date of sampling determined by the AMI method. High yields obtained for the plots maintained at reduced moisture tensions were less than those at 20 centibars. As might be expected, peanut maturity was delayed with increasing soil moisture tension (drought). Highest yield for the plot maintained at 40 centibars and for the no-irrigation plot did not occur at the sampling date determined by the AMI. However, highest yields were obtained at the AMI forecasted sampling dates in plots maintained at 60 centibars. Although yields did not differ greatly between the first and second samplings for the 60-centibar plot and the second and third samplings of the dry plots, the AMI forecasted date was later than that on which highest yields were obtained. The delay in TABLE 8. YIELD FOR THREE HARVESTS ON THE IRRIGATION TEST, WIREGRASS SUBSTATION, 19771 Yield/acre, by harvest III II I (Oct. 8) (Sept. 19) (Sept. 27) Lb. Lb. Lb. 3,234 1,683 3,8452 20 centibars ..................... 1,815 40 centibars ..................... 3,383 3,2842 2,261 3,218 3,3662 60 centibars 3 ..................... . . . . . . . . . . . . . . . .. . .. 3,4472 2,592 3,589 Nonirrigated 4 . . . . . . . . . . . . . . . . . . . 3,581 3,4892 2,765 Nonirrigated xYield values based on two to four replications were obtained from Dr. Paul Backman. 2 Harvest determined by AMI. 3 Yield values based on three replications. 4 Yield values based on six replications. Treatment DETERMINING PEANUT HARVEST DATES BY AMI 19 maturity due to reduced soil moisture was detected by the AMI method. Harvest dates for other experimental plots at the Wiregrass Substation were determined by the AMI method. Although determining the accuracy of the method was not possible because usually no more than two samplings for yield determinations were made, yields from samples taken according to the AMI were consistently high. Participating Growers In 1976, the AMI laboratory at Headland was operating on a limited scale, with the work being restricted mainly to plots at the Wiregrass Substation. However, approximately 188 Alabama peanut growers, representing nine counties, brought an average of four samples each on two to three occasions to the laboratory for analysis and a date on which to harvest their fields. This presented two problems. First, in most cases the growers had not been sufficiently instructed on how to take samples for the AMI and, second, determining accurate harvest dates by the AMI requires first-hand knowledge of the field condition by the AMI personnel. Nevertheless the samples were analyzed, and estimated harvest dates were proTABLE 9. SUMMARY OF QUESTIONNAIRES TO UNSOLICITED GROWERS WHO BROUGHT SAMPLES TO THE AMI LABORATORY, 1976 Number of growers visiting AMI lab ................................... Number of questionnaires sent ......................................... Number of responses ..................................................... Percent response' ...................................................... Average per acre yield of peanuts harvested according to AMI H igh ............................ ................................ Low ............................................................. 188 125 33 26.4 .... 3,036+666 lb. 4,440 lb. 1,958 lb. 72.2+4.7 84 63.8 1,910 Average percent TSMK of peanuts harvested according to AMI ......... High ............................................................. Low .............................. ............ ........................ Total acres not harvested according to AMI .............................. Average per acre yield of peanuts not harvested according to AMI ......................................... H igh ............................................................. Low ............................................................. 2,835+548 lb. 3,735 lb. 2,000 lb. Average percent TSMK of peanuts not harvested according to AMI ............................................. 70.9+3.3 H igh ................................................................. 74.6 Low .................................................................. 64.1 'Only about 125 questionnaires were sent because addresses were not available for some of the growers. 20 ALABAMA AGRICULTURAL EXPERIMENT STATION vided with the caution that they should be used only as a guide since the method was in an experimental stage. To follow up on the results, however, questionnaires were sent to 125 of these growers with only 26 percent responding. Of 8,295 acres planted to peanuts by responding growers, 1,707 acres were harvested according to the AMI forecasted date. In many cases yields and grades were higher for fields harvested according to the AMI forecasted date, whereas in other cases fields not harvested by the AMI made equal or higher yields and grades. Although the average yields and grades tended to be higher for peanuts from AMI harvested fields, they did not differ significantly from fields not harvested according to the AMI, table 9. The AMI program was expanded in 1977 to work more closely with Alabama growers. Seven growers each from Barbour, Henry, Houston, Geneva, and Coffee counties were selected by county agents of the Alabama Cooperative Extension Service. Peanut samples by AMI personnel were taken for analysis from designated, fields averaging about 22 acres each on farms of the participating growers. Sampling began August 3 to 19 and continued at weekly intervals to the approximate time of harvest. Yields and grades of peanuts from these fields were compared to the remaining acreage of farms of the participating growers. Although the values tended to be higher, average yield and grade for peanuts was not significantly different from those of peanuts harvested according to growers' judgment, table 10. Two problems were encountered that should be taken into consideration in evaluating these results. While the participating growers were generally cooperative, some found it difficult to delay harvest if in his judgment the field was ready to harvest, but was not ready according to the AMI. On the other hand, some growers tended to use the AMI information for harvesting all their acreage, rather than just that sampled for AMI analysis. TABLE 10. AVERAGE YIELD AND GRADE FROM PARTICIPATING GROWERS IN FIVE ALABAMA COUNTIES, 19771,2 Grade, Yield, Total acreage lb./acre pet. TSMK Harvested according to AMI ..... . 754 3,274a 73a Harvested not according to AMI . 4,448 3,149a 72a 1 Data b'iased on response from questionnaires using 27 fields as replications in the statistical analysis. 2 Values within columns with a common letter are not different at the 0.05 significance level according to Duncan's New Multiple-Range Test. Fields DETERMINING PEANUT HARVEST DATES BY AMI 21 CURRENT STATUS OF THE AMI AND OTHER METHODS FOR DETERMINING PEANUT MATURITY AND HARVEST DATES After 2 years of testing in Alabama, the AMI method is considered a valuable approach to determining peanut maturity and estimating harvest dates. Under controlled conditions and followup in the field, use of this method should result in high yields and good quality peanuts. In this study, peanut yields tended to be higher when harvested according to the AMI method as compared to other methods, although not always significantly higher. When conducted carefully, the shellout technique compared favorably with the AMI method. Probably the greatest advantage of the AMI method over other methods is that it can estimate within 2 to 4 days the optimum harvest date 2 to 4 weeks prior to that date. This allows growers to prepare a harvest timetable and take into consideration environmental factors (rain) that may interfere with harvest. Also, changes in the rate of peanut development due to environmental factors (rain, drought, disease) can also be taken into consideration in deciding harvest dates. A plot of the AMI data obtained during this 2-year study is shown in Appendix VIII. In addition to the AMI, there are other recently developed objective methods for determining peanut maturity being tested. The AMI, methanolic extract, seed-hull, and shellout methods, Appendix IX, are being tested at the National Peanut Research Laboratory in Georgia (16). Although inconclusive after only 1 year, none of the methods was completely accurate. Forecasts of harvest dates by the AMI method using samples taken 2 to 3 weeks prior to the high yield period were fairly accurate. Prediction according to the methanolic extract method using samples taken in the early part of the high yield period was acceptable. It was concluded that the shellout method may be useful but may lead to erroneous conclusions. In a similar study in Texas, it was concluded that none of the methods performed better than the shellout technique (18). In a study of the seed-hull ratio method as an estimation of optimum harvest dates in North Carolina, it was decided that firm conclusions could not be drawn about its potential until a maximum yield level is reached in that state (12). 22 ALABAMA AGRICULTURAL EXPERIMENT STATION LITERATURE CITED (1) BACKMAN, P. A., R. RODRIGUEZ-KABANA, J. M. HAMMOND, E. M. CLARK, J. A. LYLE, H. W. IVEY, II, AND J. G. STARLING. 1977. Peanut Leafspot Research in Alabama 1970-1976. Auburn Univ. (Ala.) Agr. Exp. Sta. Bull. 489. 38 pp. (2) (3) (4) BARRS, H. D. 1962. The Relationship between Kernel Development and Time of Harvesting of Peanuts at Katherine, N.T. Austrialian J. Exp. Agr. Anim. Husb. 2:106-109. BOND, D. 1972. Peanut Production Guide for Alabama. Ala. Coop. Ext. Ser. Cir. P-82. 28 pp. . 1975. Peanut Production Handbook. Ala. Coop. Ext. Serv. Cir. P-7. 24 pp. GILMAN, D. F. AND O. D. SMITH. 1977. Internal Pericarp Color as a (5) (6) (7) Subjective Maturity Index for Peanut Breeding. Peanut Sci. 4:67-70. HAMMONS, R. O., P. Y. P. TAI, AND C. T. YOUNG. 1978. Arginine Maturity Index: Relationship with Other Traits in Peanuts. Peanut Sci. 5:68-71. HENNING, R. J. AND J. F. MCGILL. 1974. When to Dig Peanuts. Ga. Coop. Ext. Ser. Peanut Release No. 53-74. (8) MASON, M. E., J. A. NEWELL, B. R. JOHNSON, P. E. KOEHLER, AND G. R. WALLER. 1969. Nonvolatile Flavor Components of Peanuts. J. Agr. Food Chem. 17:728-732. (9) MILLER, O. H. AND E. E. BURNS. 1971. Internal Color of Spanish Peanut Hulls as an Index of Kernel Maturity. J. Food Sci. 36:669-670. (10) (11) (12) MILLS, W. T. 1964. Heat Unit System for Predicting Optimum Peanut-Harvesting Time. Trans. ASAE 7(3):307-309, 312. J. A. SINGLETON, AND T. H. SANDERS. 1974. Composition Changes of Peanut Fruit Parts during Maturation. Peanut Sci. 1:57-62. PATTEE, H. E., E. B. JOHNS, , J. C. WYNNE, AND C. T. YOUNG. 1978. Seed-Hull Maturity Index-Optimum Sample Size and Effect of Harvest Date, Location, and Peanut Cultivar in North Carolina. Proc. Amer. Peanut Res. Educ. Assoc. 10:54. (13) , J. H. YOUNG, AND F. R. Cox. 1977. The Seed-Hull Weight Ratio as an Index of Peanut Maturity. Peanut Sci. 4(2):47-50. PICKETT, T. A. 1950. Composition of Developing Peanut Seed. Plant Physiol. 25:210-224. ROCHESTER, E. W., P. A. BACKMAN, S. C. YOUNG, AND (14) (15) J. M. HAMMOND. 1978. Irrigation Policies for Peanut Production. Auburn Univ. (Ala.) Agr. Exp. Sta. Cir. 241. DETERMINING PEANUT HARVEST DATES BY AMI 23 (16) (17) (18) T. H. AND E. J. WILLIAMS. 1978. Comparison of Four Peanut Maturity Methods in Georgia. Proc. Amer. Peanut Res. Educ. Assoc. 10:11-15. SANDERS, SCHENK, R. U. 1961. Development of the Peanut Fruit. Ga. Agr. Exp. Sta. Tech. Bull. NS 22. 53 pp. SCHUBERT, A. M. AND C. L. POHLER. 1978. Comparison of Maturity Test on Three Peanut Cultivars in South Texas. Proc. Amer. Peanut Res. Educ. Assoc. 10:55. (19) D. G. AND G. A. BUCHANAN. 1973. "Cultural Practices." In: Peanuts-Culture and Uses. American Peanut Res. Educ. Assoc., Inc., Stillwater, Okla. STURKIE, (20) (21) AND J. T. WILLIAMSON. 1951. "Cultural Practices." In: The Peanut-the Unpredictable Legume (a Symposium). The Nat. Fert. Assoc., Washington, D.C. VALLI, V. J. 1965. Biometeorological Factors as Predictors of Ag- ronomic Maturity of Peanuts. Tech. Note 6, Agr. Meterology Rept. No. 2. 10 pp. (22) (23) WOODROOF, J. G. 1966. Peanuts: Production, Processing, Products. The AVI Publishing Co. Inc., Westport, Conn. YORK, E. T., JR. AND W. E. COLWELL. 1951. "Soil Properties, Fertilization and Maintenance of Soil Fertility," In: The Peanut-the Unpredictable Legume. Nat. Fert. Assoc., Washington, D.C. (24) (25) (26) YOUNG, C. T. 1973. Automated Colorimetric Measurement of Free Arginine in Peanuts as a Means to Evaluate Maturity and Flavor. J. Agr. Food Chem. 21:556-558. AND M. E. MASON. 1972. Free Arginine Content of Peanuts (Arachishypogaea L.) as a Measure of Seed Maturity. J. Food Sci. 37:722-725. , Y. P. TAI, AND J. F. MCGILL. 1973. Sampling Techniques and Potential Use of the Arginine Maturity Index (AMI) Method for Determining the Maturity Level of Peanuts. Ga. Agr. Exp. Sta. Dept. of Food Sci. Memo. Rep. June. 17 pp. 24 ALABAMA AGRICULTURAL EXPERIMENT STATION APPENDIX I CHARACTERISTICS USED IN PEANUT MATURITY CLASSIFICATION Classification Mature+ Description Dark brown interhull coloration with some black splotches. Dark pink colored testa with brown splotches. Brownish interhull without any black splotches. Pink testa with very few brown splotches. Light or very faint brownish interhull coloration. Light pink colored testa without brown splotches. Whitish interhull. Large round kernel with faint pinkish colored testa. Soft, thick, spongy white interhull and very watery. Small kernel with whitish testa. Whitish interhull with a void space between interhull and kernel. Small kernel with whitish to brownish colored testa. Very small pod with a maximum length of 1.5 centimeters. Small kernel. Mature................... Intermediate............... Large seeded immature..... Small seeded immature ...... Pops Small pods ................. DETERMINING PEANUT HARVEST DATES BY AMI 25 DETERMINIG PEANUT HARVEST DA;TES BY AM! 2 APPENDIX II PERCENT DRY MATTER (DM) AND ARGININE MATURITY INDEX (AMI) FOR SAMPLES TAKEN FROM MATURITY TEST PLOTS, 19761 Maturity test plots IV III AMI DM AMI DM AMI DM AMI DM 8-3-76 24.5 194.0 18.6 243.9 21.7 244.2 20.3 266.0 8-6-76........ 28.6 171.3 21.5 218.6 22.5 222.2 22.1 249.0 8-9-76........ 29.6 153.7 26.4 191.3 25.8 203.5 25.9 208.5 8-16-76....... 36.7 106.3 27.9 154.1 30.3 148.5 31.4 159.2 8-23-76 ...... *41.4 118.4 40.8 115.2 37.6 148.9 43.8 102.7 (8-25-76)* 97.9 57.6 37.8 8-30-76....... 42.4 73.1 37.8 100.5 43.4 63.3 98.6 42.0 88.1 45.8 9-8-76........ 42.1 68.9 35.5 97.7 83.7 44.2 65.6 39.9 9-13-76....... 39.3 91.6 40.6 67.7 77.5 51.7 76.3 50.3 9-20-76....... 43.3 94.7 47.2 Sampling date 2 I II V DM 22.9 24.4 .... AMI 254.5 229.5 28.3 31.0 44.0 38.9 38.8 40.6 43.7 - 169.6 129.0 100.0 84.8 92.8 73.9 107.6 - 9-27-76....... 44.3 67.7 45.7 65.6 44.3 92.6 43.2 87.9 95.0 50.1 81.8 63.6 46.3 9-29-76....... 50.8 63.0 51.9 'Each value represents one sampling per test plot and an average of three analyses per sampling. 'DM expressed as percent of fresh weight. APPENDIX III AMI: VALUES OF PEANUTS FROM THE MATURITY PLOTS DURING 1976 Days tomaturity Mature plus 7. 0 (mature)........ 7 ................ 14 ................. 21................. 28 ................ 35 ................ Plot I 94.7 68.9 73.1 118.4 106.3 153.7 194.0 Plot II 76.3 83.7 98.6 100.5 115.2 AMI values Plot III Plot IV 77.5 87.9 65.6 67.7 63.3 88.1 57.6 97.9 148.5 293.5 -I- Average Plot V 107.6 154.1 191.3 148.9- 102.7, 73.9 92.8 84.8 100.0 129.0 169.6 72.0±: 7.2 -83.114.6 91.8±22.6 114.6±20.0 88.8± 13.0 AMID 159.2 208.5 148.9k±11.8 193.4 15.0 APPENDIX IV POD PERCENTAGE AND MATURITY CLASSIFICATION BY THE SHELLOUT METHOD ON SAMPLES TAKEN FROM MATURITY TEST PLOTS, WIREGRASS SUBSTATION, 19771 Maturity plots 2 Sampling date 9/23 9/29 9/23 9/29 9/23 9/29 9/23 9/29 9/23 9/01 9/05 9/01 9/05 Mature+ 13 + 3.8 17± 3.0 15 ± 6.0 16 + 5.6 4 + 2.7 15 + 8.2 2 1.5 12 ± 4.0 20± 2.1 20 ±11.0 18 ± 7.2 15 ± 3.2 18 ± 1.5 + Mature12 + 2.3 22 + 3.8 16 ± 3.6 20± 1.2 7 ± 4.1 25 + 3.8 13 ± 7.9 14 + 4.4 12 + PDIFC ..... PD2 FC ..... PD3 FC ..... PD 4 FC ..... PD 1FP . PD 2 FP. PD 3 FP. PD 4 FP ..... Maturity classification Small Large seeded seeded Intermediate immature immature 23 + 7.4 15 + 6.8 15 5.3 18 + 4.0 18± 1.2 10 2.9 34 +15.9 16 + 3.2 48 ±12.4 17± 1.5 34 ±17.7 15 ± 7.6 23 + + Pops 8 7 7 12 9.5 3.1 5.3 3.5 ll pods 13 10 4.9 9.0 Total no.pods 171 146 139 143W 123 129 155 181 146 151 151r 173 176 203m 109 C D 14 ± 9.1 18 ± 2.3 18 ±10.0 22 + 4.1 18± 1.2 20 + 3.1 17± 6.7 23 6.4 17 ± 1.2 4.2 21 17 ± 2.1 + 11± 4.6 8 4.7 9 + 2.3 12 4.5 12 ± 3.5 18 3.2 11± 3.8 21 2.5 19± 3.6 14 2.5 17± 5.6 5± 2.1 11 3.5 14 ± 7.5 5 ±3.5 20 ±10.5 14 8.5 12 4.4 r- 2 ± 2.1 5 ±4.2 2 ± 1.5 7± 4.2 5± 3.1 4 ± 1.7 2± 1.5 1 0.6 2± 2.5 2 0.6 2 ± 2.1 n 5.0 6.5 7 2.5 11 ± 4.4 9± 1.7 15 1.5 13 4.6 18 ± 4.4 1.0 21 16 ± 0.6 ± 12± 5.1 16± 4.6 20± 3.5 15 5.6 14 3 ± ± 9/16 11± 3.6 11 4.1 17 ± 3.6 16± 3.1 29 ± 2.5 9/23 17 3.6 22 ±10.0 16 ± 7.0 21 5.5 21 7.6 'Each value is a percentage of total sampled and represents an average of three samples.2Planting dates (PD) following corn (FC) or following peanuts (FP). ± x m z -I m 3.1 2.7 0 z 0 -a z APPENDIX V PERCENT DRY MATTER (DM) AND ARGININE MATURITY INDEX (AMI) VALUES FOR PEANUT SAMPLES TAKEN FROM MATURITY PLOTS PREVIOUSLY PLANTED TO CORN OR PEANUTS, 19771 M z Plot V AMI 204.7 266.7 321.5 236.8 196.5 135.6 112.7 90.7 236.8 203.7 190.5 161.6 122.0 97.9 87.7 87.0 m Sampling Plot I AMI date DM Following corn: 8- 8-77 ........... 8-15-77............29.9 144.1 8-22-77............27.2 179.9 8-29-77............33.4 153.1 9- 5-77............ 38.7 115.2 107.3 9-12-77............38.3 112.2 9-19-77............ 38.4 9-26-77............ 40.9 96.6 Following peanuts: 8- 8-77............ 8-15-77............ 8-22-77............ 8-29-77............ 9- 5-77............ 9-12-77............ 9-19-77............ 9-26-77............ 'Each value represents - Plot II DM 22.1 23.9 26.0 30.2 36.4 38.1 40.1 42.2 AMI 99.7 138.1 201.6 205.8 159.0 128.7 103.6 87.6 DM 19.1 24.2 23.2 28.5 33.4 38.3 40.4 41.3 Plot III AMI 118.2 195.4 241.9 223.6 176.9 134.8 102.6 87.2 112.0 97.7 121.4 114.5 108.0 88.0 93.4 76.8 DM 17.1 20.8 25.4 27.2 34.6 38.1 37.1 41.5 29.1 34.4 38.4 41.2 44.0 45.1 46.9 44.4 Plot IV AMI 129.7 232.9 216.8 259.3 163.1 131.1 107.5 82.7 127.6 149.0 121.8 119.0 97.8 85.9 85.5 82.5 DM 12.7 18.1 18.5 26.6 31.9 35.4 37.0 39.7 20.2 27.5 28.5 34.7 38.3 43.1 44.9 44.1 -I ., W 27.1 168.1 26.8 214.8 29.9 169.0 35.2 163.5 37.2 118.6 39.2 119.9 41.5 104.7 an average of two to 24.3 91.8 30.8 23.9 162.8 37.1 23.7 252.7 38.7 40.1 29.2 235.3 174.7 42.4 35.3 48.5 135.6 45.0 40.3 129.4 44.9 44.4 44.2 86.3 three samples per sampling date. N4 APPENDIX VI AMI VALUES FOR PEANUTS FROM MATURITY PLOTS AT THE WIREGRASS SUBSTATION, 1977 AMI values Days from maturity 0 Plot I1,2 FC 4 FP Plot II FC FP Plot III FC FP5 Plot IV FC FP5 Plot V FC FP 87.0 - Average AMP FC 87.5k 3.3 106.6 4.6 r FP 87.0 88.0 85.5 ................... 7...... ............. 96.6 87.6 86.3 87.2 108.0 82.7 85.9 90.7 14 .................... 112.2 104.7 103.6 129.4 102.6 114.5 107.5 97.8 112.7 21 .................. 107.3 119.9 128.7 135.6 134.8 121.4 131.1 119.0 135.6 115.2 118.6 159.0 174.7 176-.9 97.7 163.1 121.8 196.5 28.................. 149.0 236.8 163.5 205.8 235.3 223.6 .112.0 259.3 35.................153.1 42.. 179.9 169.0 201.6 252.7 241.9 216.8 127.6 321.5 'Peansuts planted 4-7-77 at the Wiregrass Substation were not part of the maturity plots.C 2 Each value represents an average of two to three samplings.D 3 Averages do not include AMI values from Plot I (see footnote 1).r 4 See table 6 for meaning of abbreviations. 5 Values not used in calculating AMI averages because "continuous cropping" was occurring 87.7 97.9 122.0 161.6 132.6± 3.2 113.7±22.3 87.0 1.0 190.5 203.7 231.4±22.5 173.9±16.9 128.8± 9.6 245.5±53.4 212.9±31.7 228.239.6 168.2± 93 o C (see text). M X z -4 Co) -.I 0 z DETERMINING PEANUT- HARVEST DATES BY' AMI 29 DETERMININGHARVEST DATES BYAMI PEANU AMI MATURITY PLOTS 1976 + 1977 2' 0 35 28 21 14 7 0 -7 Days to harvest Relation between AMI values and time of harvest for the maturity test plots at the lines Wiregrass Substation in 1976 and 1977 is shown by-the dotted line represent standard deviation. 'Solid 30 ALABAMA AGRICULTURAL EXPERIMENT STATION APPENDIX VIII AMI FIVE ALABAMA COUNTIES 1977 200 150 100 50 35 28 21 14 7 Days to harvest 0 -7 Relation between AMI values and time of harvest for the maturity test plots at the Wiregrass Substation and for fields of participating growers in 1977 is shown by the dotted line. Solid lines represent standard deviation. DETERMINING PEANUT HARVEST DATES BY AMI 31 APPENDIX IX METHODS OF DETERMINING PEANUT MATURITY Method (abbreviation) Arginine maturity index (AMI) -------- -- Description Based on the relation between the seed free arginine contentdry matter ratio and maturity; AMI values decrease with increasing peanut maturity. Based on the change in color (light transmittance) of a methanol extract of peanuts; the percent transmittance of this extract decreases with increasing maturity. Methanolic extract (ME) .... Seed-hull ratio fresh weight maturity index (FMI) .................... dry weight maturity index (D M I) .................. Based on the ratio of seed and hull fresh weights; ratio increases with increasing maturity. Based on the ratio of seed and hull air dried weights; ratio increases with increasing maturity. Based on a change (darkening) of the internal pericarp color; increased darkening with increasing maturity. v r Shellout technique ......... I Alabama's Agricultural Experiment Station System AUBURN UNIVERSITY With an agricultural research unit in every major soil area, Auburn Un iversit\ serves the needs of field crop, livestock, forestry, and horticulrar"l pro ducers in each region in Alabama. Ev erx citi zen of the Stare has a stake in this research progrIm. since any advantage from neXx and more econom-~ ical wax s of ploducing and handling farm products di rectly benefits the cofnsuming public. (0 r, , 1 I nr--- + o. ® Main Agricultural Experiment Station, Auburn. E. V. Smith Research Center, Shorter. 1. 2 3 4. 5. 6 7 8. 9. 10 11 12 13. 14 15 16 17 18 19. 20 Tennessee Valley Substation, Belle Mina. Sand Mountain Substation Crossville North Alabama Horticulture Substation, Cuilman Upper Coastal Plain Substation, Winfield. Forestry Unit, Fayette County Foundation Seed Stocks Farm. Thorsby. Chilton Area Horticulture Substation, Clanton Forestry Unit, Coosa County. Piedmont Substation. Camp Hill. Plant Breeding Unit, Tallassee. Forestry Unit, Autauga County. Prattville Experiment Field, Prattville. Black Belt Substation, Marion Junction. The Turnipseed-Ikenberry Place, Union Springs Lower Coastal Plain Substation, Camden. Forestry Unit, Barbour County Monroeville Experiment Field, Monroeville Wiregrass Substation, Headland Brewton Experiment Field, Brewton. Solon Dixon Forestry Education Center, Covington and Escambia counties 21 Ornamental Horticulture Field Station, Spring Hill. 22. Gulf coast Substation, Fairhope.