In the present study we analyzed the responses of wheat to mild salinity and drought with special emphasis on the so far unclarified interaction of these important stress factors by using high-throughput phenotyping approaches. Measurements were performed on 14 genotypes of different geographic origin (Austria, Azerbaijan, and Serbia). The data obtained by non-invasive digital RGB imaging of leaf/shoot area reflect well the differences in total biomass measured at the end of the cultivation period demonstrating that leaf/shoot imaging can be reliably used to predict biomass differences among different cultivars and stress conditions. On the other hand, the leaf/shoot area has only a limited potential to predict grain yield. Comparison of gas exchange parameters with biomass accumulation showed that suppression of CO 2 fixation due to stomatal closure is the principal cause behind decreased biomass accumulation under drought, salt and drought plus salt stresses. Correlation between grain yield and dry biomass is tighter when salt- and drought stress occur simultaneously than in the well-watered control, or in the presence of only salinity or drought, showing that natural variation of biomass partitioning to grains is suppressed by severe stress conditions. Comparison of yield data show that higher biomass and grain yield can be expected under salt (and salt plus drought) stress from those cultivars which have high yield parameters when exposed to drought stress alone. However, relative yield tolerance under drought stress is not a good indicator of yield tolerance under salt (and salt plus drought) drought stress. Harvest index of the studied cultivars ranged between 0.38 and 0.57 under well watered conditions and decreased only to a small extent (0.37–0.55) even when total biomass was decreased by 90% under the combined salt plus drought stress. It is concluded that the co-occurrence of mild salinity and drought can induce large biomass and grain yield losses in wheat due to synergistic interaction of these important stress factors. We could also identify wheat cultivars, which show high yield parameters under the combined effects of salinity and drought demonstrating the potential of complex plant phenotyping in breeding for drought and salinity stress tolerance in crop plants.

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Field experiment was conducted to study the effect of water stress on yield and yield traits of durum wheat and bread wheat genotypes. Water stress caused significant reduction in plant height (PH), peduncle length (PL), spike number/m 2 (SN), spike length (SL), spike width (SW), spikelets number/spike (SNS), spike mass (SM), grain number/spike (GNS), grain mass/spike (GMS), biological yield (BY), thousand kernel mass (TKM), grain yield (GY) and harvest index (HI). Wheat traits such as SN, SM, BY, TKM, GY were more vulnerable to drought stress. Positive significant correlation of GY with SN, BY and HI under rain-fed condition was found. Genotypes of durum wheat were more sensitive to drought than that bread wheat genotypes. The significant and positive correlation of GY with Stress Tolerance Index (STI), Mean Productivity (MP) and Geometric Mean Productivity (GMP) indicated that these indices were more effective in identifying high yielding, drought tolerance genotypes.

We aimed to study the influence of soil water deficit on gas exchange parameters, dry matter partitioning in leaves, stem and spike and grain yield of durum (Triticum durum Desf.) and bread (Triticum aestivum L.) wheat genotypes in the 2013-2014 and 2014-2015 growing seasons. Water stress caused reduction of stomatal conductance, photosynthesis rate, transpiration rate, an increase of intercellular CO 2 concentration. Photosynthesis rate positively correlated with growth rate of genotypes. Drought stress caused adaptive changes in dry matter partitioning between leaves, stem and spike of wheat genotypes. Stem dry mass increased until kernel ripening. Drought stress accelerated dry mass reduction in leaves and stem. High growth rate of spike dry mass was revealed in genotypes with late heading time. Spike dry mass positively correlated with photosynthesis rate and grain yield. Generally, bread wheat is more productive and tolerant to drought stress than durum wheat.

Abstract:The purpose of this research was to study the influence of rust diseases on photosynthetic rate of the created local varieties and introduced variety samples of wheat. Experiment was carried out with two variants-control and 25% Tilt treatment. The 25% solution of Tilt was used to prevent disease infection. The photosynthetic rate was measured by T-type URAS-2 infrared gas analyzer (made in Germany). Disease infection rate was determined based on the Cobby balling scale. Ontogenetic and daily rate of photosynthesis by effect of the disease were decreased. The amount of assimilated CO 2 during the day and vegetation period linearly depends on the disease infection degree. At the same time, the activation of non-infected parts' photosynthetic rate of some varieties was observed. The difference reaches up to 87% between the variants as a result of the rapid aging of photosynthesis apparatus.