Response of some wheat genotypes morphogically in grain yield and its components and molecularly in gene expression of drought tolerant genes grown in moisture depletion levels

Abstract

A field experiment was carried out in the fields of the College of Agricultural Engineering Sciences - University of Baghdad for the seasons 2018-2019 and 2019-2020. A randomized complete block design (RCBD) was used in a split plot design with three replications for the two seasons. Eight genotypes of bread wheat and durum wheat add in the aim : molecular work were planted individually to test their ability to tolerance moisture stress, the genotypes occupied the secondary plots, and moisture depletion levels were 50, 70 and 90% of the ready water main plots. The results showed that reducing the moisture depletion to 50% of the ready water caused an increase in most of the yield components, as it was superior in giving the highest mean number of spikes (26.67 and 23.21 spike plant^-1), the number of grains per spike (77.67 and 73.00 grain spike^-1), and the highest weight of 1000 grains (44.46 and 43.42 gm) and the biological yield (82.61 and 78.33 gm plant^-1), and this confirms the improvement of the photosynthetic system ability, as it gave the highest mean grain yield (43.42 and 38.76 gm plant^-1). Plants grown under this moisture level were distinguished in increasing their efficiency in CO₂ assimilation, as it gave the highest mean harvest index (53.33 and 46.23%) for both years respectively. The two genotypes Um- Rabee and Al-Noor were superior in their ability to tolerance different levels of moisture depletion, and represented by giving the highest means in the number of spikes (23.00,  23.22 , 21.44 and 21.00 spike plant^-1) and the number of grains in a spike (63.00, 63.34, 69.90 and 67.90), and the superiority of Um- Rabee in giving the highest mean weight of 1000 grains (38.23 and 40.04 gm), and this shows the ability of this composition to give the highest yield of grains (40.46, 40.67,  34.61 and  33.94 gm plant^-1) for the two genotypes respectively. The high levels of moisture depletion led to the high levels of gene expression in the drought-tolerant NAC, GSK and dreb gene. From this, we conclude that the availability of the appropriate quantities of irrigation water worked to create a balance, activate metabolic processes, and increased the efficiency of photosynthesis and reflected positively on the yield of the plant, and that the decrease in the quantities of irrigation water caused the high levels of gene expression that increased the plant’s ability to tolerance water stress.

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