| Cultivated cotton shows a negative response to high temperatures, mainly with regard to pollen viability, thus temperature is highly correlated to seed and fiber production. The objectives of this study were (1) to identify genetic sources of heat tolerance where the expression overlaps in both the gametophyte and sporophyte; (2) to study the inheritance, heritability and transference of pollen heat tolerance to a susceptible genotype; and (3) to correlate pollen heat tolerance with salt and drought tolerance at the cellular level.;The genotype 7456 showed an overlap of heat tolerance expression in the gametophyte and sporophyte. Data from the inheritance study suggested that one or two genes of partial dominance are involved in pollen heat tolerance. The narrow sense heritability estimate was 65.2%. When heat tolerance was transferred to Paymaster 404, the BC(,1) showed reduced but adequate fertility and both the F(,1) and BC(,1) populations showed overlapping expression of the tolerance. The heat-tolerant genotypes showed a tendency to be salt- and drought-tolerant. Paymaster 404 showed salt and drought susceptibility. It is suggested that the mechanism responsible for all of these tolerances is the same. Cotton and Atriplex cells showed a different response to salt and drought conditions.;The inheritance, heritability and transfer study was done by means of pollen selection. Cotton pollen was heat treated at 35(DEGREES)C for 15 hrs prior to anthesis. Pollen heat tolerance was transferred from the tolerant genotype 7456 to the heat susceptible cultivar Paymaster 404 by the classical backcross method. For the study at the cellular level, slinity and drought conditions were simulated with NaCl and Polyethylene Glycol 8000, respectively. Salt and drought tolerance of cell cultures of the heat-tolerant genotypes 7456 and F(,1) (7456 x Paymaster 404) and of the heat-susceptible cultivar Paymaster 404 were also compared to cells of the halophyte Atriplex griffithssii, which expresses high natural tolerance to heat, salinity and drought. |
