Germination of cottonseeds (Gossypiura hirsutum L.) is reduced by preharvest exposure to,weather, particularly if conditions are warm and humid. To identify some of the germination processes affected by weathering deterioration, seedlots of six cultivars were harvested before and after a period of field exposure and comparative germination studies were conducted. Seedling field emergence was reduced by 11 to 33% due to weathering. During imbibition, weathered seeds of sensitive cultivars released more K+, Mn2+, Mg2+, and Ca2+, but less Na+ into the steep solution than did their unweathered counterparts. Leaching of individual minerals was a better indicator of seed quality than was the total release of electrolytes; release of K+ Ca2+ than was significantly correlated with measurementosf seed quality. Respiratory O2 uptake was reduced in deteriorated seeds, with elevated estimates of the RQ after 7.5 h of imbibition. Aeration with 100% O2 increased O2 uptake and reduced the RQ, indicating that O2 diffusion may have limited respiration during early germination. Weathering deterioration of membranes was confirmed by electron microscopy of cotyledonary lipid and protein bodies. Thesed ata indicate that the loss of membrane functional integrity is a major factor responsible for the reduction of germination potential by weathered seeds, and that the release of K+ and Ca2+ into steep water during imbibition may be a good indicator of cottonseed planting quality.

Previous research on nutrient distribution in cotton (Gossypium hirsutum L.) has generally been conducted on a crop canopy base. To enable measurement of mineral nutrient demand by developing cotton bolls, it was necessary to examine the distribution of minerals among fractions of cotton bolls at specific developmental stages. Distribution of N, P, K, Ca, Mg, and Mn among the bur (carpel walls), seed, and fiber fractions of cotton bolls was measured between 10 days after flowering and maturity. During the initial 3‐week phase of boll enlargement, the bur accumulated reserves of N, P, and Mg which were subsequently drawn upon, presumably by the seed and fiber, during later development. The bur continuously accumulated K; bur K concentration was 5.5% at maturity. Concentration of most minerals in the seed declined initially, but then increased markedly later. The major mineral accumulated by the seed was N. At boll opening, over 90% of the boll N was in the seed. The fiber accumulated minerals during the first 5 weeks of development, but lost most of them during the final 3 weeks. The most abundant mineral in the fiber was K. Redistribution of minerals among the boll fractions appeared to have occurred. If it did, it could have partially accounted for the final patterns of mineral distribution. The data suggested that the boll remained a physiological continuum throughout development.

This study was conducted to determine the metabolic events occurring during cottonseed development as revealed by N and amino acid compositions of both the whole seed and the free amino acid pool. Flowers on field grown cotton (Gossypium hirsutum L.) plants were tagged the day of anthesis, and bolls were sampled at intervals between 10 days after bloom and maturity. Developing seed were analyzed for both total N and nonprotein N (NPN). While total N was accumulated by the seed throughout development, NPN increased until 21 days after anthesis and then declined. At boll opening, only about 1% of the total N was in the NPN fraction.Amino acid compositions of the seed and the NPN fraction were also determined. In juvenile seed tissue, over 50% of the NPN was accounted for by asparagine. Other amino acids prominent in this free amino acid pool of young cottonseed were, in descending order, glutamine, aspartic acid, glutamic acid, and arginine. At maturity, asparagine and glutamic acid each accounted for about 15% of the NPN. Gamma‐amino butyric acid and ethanolamine were also observed in the NPN fraction. Significant shifts in total amino acid distribution were seen to occur during the fourth week of seed development. The amino acid profile of cottonseed after the fifth week of development closely approximated that of mature seed.

Among cotton (Gossypium hirsutum L.) seeds with densities less than 1.00 g cm−3, germination performance has been shown to be proportional to the seed density. Since cotton seeds produced in the mid‐South usually attain densities higher than 1.00 g cm−3, we evaluated the germination performance of seeds with densities ranging from ≤ 1.00 to 1.10 g cm−3 to determine if the proportionality between seed density and germination performance might extend beyond 1.00 g cm−3. In laboratory, greenhouse, and growth chamber studies, maximum germination and sustained seedling growth were produced by seeds with initial densities of 1.04 and 1.06 g cm−3. The quantity of oll in the seeds was increased with seed density, but both seed weight and seed volume were decreased in the higher density seed classes. The ratio between seed oil and seed protein contents increased through a seed density of 1.06 g cm−3, then decreased slightly. Germination and seedling growth exhibited the same response to density classification as did the oil:proteln ratio. The principal deficiency of the high density cotton seeds appeared to be the low weights of cotyledonary reserves available for mobilization during germination. Selection of cotton seeds on the basis of density should therefore be done so that the small volume, light weight, but high density seeds are eliminated with the low density seeds.

Utilization of seed protein from cotton (Gossypium hirsutum L.) as an ingredient of food products for nonruminant animals may provide producers with a salable seed commodity in addition to oil and meal. It was therefore important to establish the effects that environmental conditions migbt have on cottonseed protein quantity and quality (amino acid composition).Cotton was grown at two levels of N fertility at each of two locations in Mississippi. At each location, N concentration was higher in cottonseed produced in high‐N N plots than in seed produced in low‐N plots. For the single harvest at Starkville, enhancement of seed N by fertilization was 1.18%. For the first five harvests at Stoneville, enhancement of seed N ranged from 0.85 to 1.10%. A stratified harvest at Stoneville enabled the identification of seasonal influences on seed size and chemical composition. Both seed size and seed N concentration decreased with later developmental periods. Seed oil concentration, however, increased with later developmental periods.Both N fertility and seasonal patterns caused slight, but statistically significant, changes in the amino acid composition of cottonseed protein. Generally, as seed N increased, the concentrations of lysine, threonine, glycine, and alanine in the seed protein decreased; concentrations of arginine and glutamic acid increased. Because both N fertilization and seasonal factors can influence cottonseed protein quantity and amino acid composition, comparisons of these factors should be made only among environmentally similar samples.