Commercialization of New Industrial Crop Germplasm and Cropping Systems
Location: Plant Physiology and Genetics Research
Title: Water stress causes differential effects on germination indices, total soluble sugar and proline content in wheat (Triticum aestivum L.) genotypes
Submitted to: African Journal of Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 9, 2011
Publication Date: October 19, 2011
Citation: Qayyum, A., Razzaq, A., Ahmad, M., Jenks, M.A., 2011. Water stress causes differential effects on germination indices, total soluble sugar and proline content in wheat (Triticum aestivum L.) genotypes. African Journal of Biotechnology, Vol. 10(64), pp. 14038-14045.
Interpretive Summary: Current estimates indicate that 25% of the world’s agricultural land is now affected by high levels of water deficiency. Water deficient environments due to increasing climatological drought, dwindling aquifers, and salinization are among the major causes of crop loss worldwide, commonly reducing average yield for many crops by more than 50%. To determine whether significant genetic variation in traits associated with drought tolerance during early plant development exist in wheat grown in arid and semi arid zones of Pakistan, five wheat cultivars from the Punjab province were subjected to five levels of osmotic stress, and its effect on germination percentage, mean germination time, coleoptile length, and early seedling proline and sugar content was assessed. For all cultivars, germination percentage, mean germination time and coleoptile length were shown to decrease with increasing osmotic stress, whereas proline and sugar content was shown to increase with increasing osmotic stress. The results of this study also show that significant genetic variation exists among these five wheat genotypes for these osmotic stress responses. Previous studies indicate that cultivars that perform best in these assays should also produce the best yields in arid and semi-arid environments. Besides revealing mechanistic determinants of stress tolerance in these wheat cultivars, results here also reveal excellent parental material for use in breeding improved drought stress tolerant wheat.
Different cultivars differ inherently in their response to drought and those cultivars best adapted to growth in arid and semiarid conditions form the most uniform and vigorous stands when grown under water deficits. The seeds of five wheat cultivars (GA-2002, Chakwal-97, Uqab-2000, Chakwal-50 and Wafaq-2001) were subjected to five different levels of osmotic stress; 0 bars (distilled water, control), -2, -4, -6 and -8 bars to assess the effect of osmotic stress on germination percentage, mean germination
time, coleoptile length, proline and sugar amounts. The investigations were performed as factorial experiments under complete randomized design (CRD). Germination percentage, mean germination time and coleoptile length were shown to decrease with increasing osmotic stress, whereas a progressive increase in proline and sugar content were observed with increasing osmotic stress. The response of five cultivars examined under various levels of osmotic stress differed dramatically. Chakwal-50 and GA-2002 were amongst best performers, showing high germination rate, longest coleoptile length, highest proline values and sugar contents when compared with other cultivars under stress conditions. These were proven to be the most tolerant cultivars. Performance of Wafaq-2001 and Uqab-2000 were poor when compared to the other cultivars under limited water stress conditions.