Evaluation of stem reserve mobilization in Egyptian bread wheat (Triticum aestivum L.) genotypes and F1 hybrids under post-anthesis chemical desiccation stress

Abstract

The assimilation of stem reserves by pre-anthesis is regarded as an essential source of grain filling during abiotic stresses that inhibit photosynthesis during post-anthesis. Twenty-one Egyptian wheat genotypes and F1 hybrids were evaluated using potassium iodide (0.4% KI) induced desiccation stress 14 days after anthesis for stem reserve mobilization (SRM). For a percentage reduction in grain weight under chemical desiccation stress, the measured genotypes differed significantly (P<0.01). The stress tolerance index for grain weight varied from 85.88 to 97.67%. The minimum reduction was observed in Gemmiza-10 x Sids-12 (85.88 %) showing the lowest SRM while in Gemmiza 7 x Gemmiza 11 (97.67%) showing the highest utilization of SRM, the maximum reduction in grain weight was reported. A strong negative correlation (r = 0.037) was observed between the percentage decrease in grain weight and plant height. In conclusion, when subjected to post-anthesis chemical desiccation that prevents photosynthesis, tested genotypes differ considerably in stem reserve use. In the absence of photosynthesis, genotypes with better SRM dependent grain growth can also have relative drought tolerance. Therefore, this approach can be used to indirectly screen the genotypes of wheat for better output under conditions of terminal drought.