No abstract

Five cultivars of peanuts, (Aruchis hypogueu L.), Florunner,Tihn, Florigiant, Ga. 194 Va. and Early Bunch, were grown at Tifion, Ga. on a Stilson loamy sand, low in calcium (356 kg/ha), and at Plains, Ga. on a Greenville sandy loam, relatively higher in calcium (752 kg/ha), for three years (1977-79) to study the response of yield, grade and incidence of pod rot with applications of gypsum. Plots were topdressed with 0, 560, 1120, or 1680 kg/ha of gypsum. Pod rot did not occur at Plains and no significant difference occurred among gypsum rates for yield, percentages of sound mature kernels (SMK), extra large kernels (ELK), and value/ha for any cultivar. However, significant differences were detected for these variables among cultivars. At Tifton, severe pod rot occurred on plots receiving no gypsum, but the severity decreased for all cultivars as the rate of gypsum applied was increased. Differences in yield, percentages of SMK, ELK, pod rot, value/ha and kernel calcium occurred among cultivars, grown at different gypsum rates. Florunner was significantly higher in yield, percent SMK, and value/ha than the other cultivars at all gypsum rates, and significantly lower in pod rot at 0 and 560 kg/ha gypsum. The amount of calcium in kernels increased for most cultivars as rates of gypsum increased. These data support previous work which indicated a suppression of pod rot and an increase in yield and kernel calcium with applications of gypsum.

Manganese deficiency of peanut (Arachis hypogaea L.) is a common problem on some soils of the Coastal Plain region of the southern USA. Information is limited, however, on the concentration of Mn required in the peanut plant. 'Fiorunner' peanut was grown on a Pelham sand (loamy, siliceous, thermic, Arenic Paleaquult) to determine soil pH and Mn effect11 on Mn nutrition of peanut. Soilapplied Mn treatments of 0, 10, 20, and 40 kg ha-• were compared at pH levels near 5.2, 6.0, and 6.8. Manganese deficiency occurred only on plots with pH levels near 6.8 where yields were increased by applying up to 40 kg Mn ha-•. Critical Mn levels were 13,15,15,15,13, and 12 mg kg-• in leaves collected at 7, 9, 11, 13, 15, and 17 weeks after planting, respectively. Pod yields averaged 3.41, 5.40, and 5.73, and 6.37 Mg ha-• at pH level near 6.8 for 0, 10, 20, and 40 kg Mn ha-• tt.eatments, respectively. Maintaining a soil pH near 6.0 provided a desirable medium for peanut production without the need for Mn fertilizer.------------------

Synopsis The rate of depletion of soil phosphorus and potassium when omitted from the fertilizer increased with increasing rates of nitrogen application. Potassium became critical sooner than phosphorus on the Tifton loamy sand. Maintenance fertilizer consisting of a 4‐1‐2 ratio produced hay yields equal to those resulting from higher amounts of phosphorus and potassium.

Experiments were conducted to characterize the response to Ca of two recently released peanut (Arachis hypogaea L.) cultivars, ‘Tifrun’ and ‘Early Bunch’ and to compare their response to that obtained from ‘Florunner’, ‘Florigiant’, and ‘NC-Fla 14’. Gypsum (CaSO4•2H2O, approximately 72% CaSO4) was applied at rates of 0 and 1,121 kg/ha in a split plot design using the above cultivars. The experiment was conducted on Fuquay loamy sand low in Ca content and on Greenville sandy loam relatively high in Ca content. Yield, percent sound mature Kernels (% SMK), percent extra large kernels (% ELK), and percent oil in the seed were measured. The peanut cultivars differed in their response to soil Ca level and to Ca fertilizaton. Gypsum applications did not increase % SMK and yield of Florunner significantly when soil Ca content was low and pH adequate, whereas the other four cultivars produced large increases in these factors. Gypsum applications to the low Ca soil with high pH increased the percent oil 4.0% for all varieties every year. The response of Tifrun and Early Bunch to gypsum fertilization was similar to Florigiant and NC.FLA 14 Tifrun quality factors and yields were comparable to Florunner on the Greenville soil without supplementary Ca, whereas Ca fertilization of the Fuquay soil was necessary. Early Bunch was similar to Florigiant and NC-Fla 14 in both yield and quality factors.