Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 19, 1996
Publication Date: N/A
Interpretive Summary: Chilling (nonfreezing) temperatures after cotton plants have emerged from the soil can harm young seedlings and result in lower lint yield at harvest. We conducted this research to (1) compare the chilling sensitivity of different varieties, and (2) determine if a laboratory procedure was useful in predicting how these different varieties responded to chilling temperatures in the field. We found the cotton varieties that grow rapidly as seedlings were more sensitive to chilling temperatures. We also found that by measuring the amount root length is reduced by chilling temperatures in the laboratory, researchers may be able to tell which varieties will be least harmed by cold temperatures in the field. These results are important to plant breeders and agronomists who are studying ways to improve cotton performance in areas where chilling temperatures often occur after cotton planting.
Technical Abstract: Cotton (Gossypium hirsutum L.) genotypes that are less sensitive to chilling temperatures may improve productivity in areas where late-spring cold fronts are common. Our objectives were to compare chilling tolerance of four genotypes differing in maturity and to determine whether seedling growth responses of genotypes to cool temperature in a controlled environ- ment are valid predictors of field performance. The four genotypes studie were 'DPL 20' (early maturity), 'DPL 50' (mid), 'DPL 5690' (late), and 'DPL Acala 90' (late). Cotyledon area, root and shoot length, and root and shoot fresh weight were measured after four-day-old seedlings were exposed to temperatures of 15, 20, 25, and 30oC for six days. In a field experiment, the genotypes were planted in mid-April, early-May, and mid-May at Florence SC, in 1991 and 1992. Root length was the only seedling trait for which the temperature response was genotype dependent. Root length of DPL 5690 and DPL Acala 90 was the same at all assay temperatures while root length of DPL 20 and DPL 50 was reduced by cool temperatures. In the field, the two earlier maturing genotypes emerged faster but yielded less than the other two genotypes when chilling temperatures occurred after planting. The results suggest that seedling root length inhibition by suboptimal tempera- tures may be a useful screening tool for determining chilling sensitivity in cotton.