The development of a rapid test to predict cotton lines (Gossypium spp.) which exhibit increased resistance to chilling injury would be a valuable breeding tool. The objective of this study was to evaluate the relationship of Pima cottonseed (G. barbadense L.) lipid composition to seed germination and seedling emergence under field conditions with low soil temperatures. Seed fatty acid methyl esters of selected genotypes were analyzed by gas‐liquid chromatography. Total seed lipid was fractionated into polar and neutral components and their associated fatty acid methyl esters were similarly analyzed. Low correlations were obtained between unsaturated/ saturated (U/S) fatty acid ratios of total seed lipid and laboratory germination percentages. However, seedling emergence under field conditions with low soil temperatures correlated strongly with U/S fatty acid ratios of total seed and polar lipids (r = 0.97** and 0.95% respectively)3. No advantage was realized by using polar lipids over total seed lipid for the analysis. Results of this study suggest the feasibility of using the rapid analysis of total seed lipid associated U/S fatty acid ratios for identifying cotton lines with chilling resistance during seed germination and emergence.

Chilling damage was examined in the chilling‐sensitive plant Gossypium barbadense. Between 30 and 36 h of germination at 34°C, the seedlings are extremely sensitive to temperatures below 10°C. The initiation of chilling damage by exposure to 2°C for 5 h during the sensitive period resulted in a large reduction in DNA synthesis. The reduction was correlated with a reduced efficiency of nuclear DNA polymerase activity. Comparing a more chilling resistant genotype to a more sensitive variety indicated that the resistant genotype nuclear DNA polymerase activity is more efficient when exposed to a chilling stress. Resistance was also correlated with a higher degree of unsaturated fatty acid content in the nuclear membranes of the resistant variety.

Effects of exogenous free fatty acid application on percentage germination and radicle length were investigated with more chill sensitive (Pima S-4) and less chill sensitive (Pima S-5) cottonseed (Gossypium barbadense L.) at chilling (14°C) and optimal (34°C) temperatures. Of the organi(f solvents able to solubilize free fatty acids, aqueous solutions as high as 5% dimethyl sulfoxide did not adversely affect germination at 34°C. Palmitic, oleic and linoleic acids (120 fiM) were solubilized in 5% DMSO.At 14°C, percent germination of fatty acid treated Pima S-5 significantly increased, while no difference was observed for Pima S 4. Conversely, radicle length of fatty acid treated Pima S-4 significantly increased especially with oleate and linoleate, while no difference was detected for Pima S-5. Fatty acid supplementation influenced neither germination nor radicle length for Pima S-4 and Pima S-5 at 34°C.

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