The Study of Different Irrigation Regimes on the Osmoregulation of Pollen Grain and Chlorophyll and Proline Content in Wheat Genotypes (Triticum aestivum L.)

Drought stress reduces the water potential of the soil and in such conditions the plant can osmoregulation in order to preserve and continue water absorption. Osmoregulation in flag leaf and pollen grains can be used as an indicator in wheat breeding programs to increase drought tolerance. The aim of this study was to study drought tolerance and selection of the most tolerant genotype of wheat through the effect of different irrigation regimes on chlorophyll, proline, osmoregulation of pollen grains and selection of the best genotypes for planting in arid and semi-arid regions with high yield.

In order to analyze the effects of three different humidity regimes on the osmoregulation of pollen grain, chlorophyll and proline content three different experiments were carried out in randomized completely block designs with three replications. The three different humidity regimes included normal conditions (without stress), water-stress in meiosis stage and continuous water stress (30% of Field Capacity). The genotypes studied in this experiment included Alvand, Ehdaei 81, Ehdaei 82, Oxley and Chinese Spring.

The results of analysis of variance in non-stress and stress conditions showed that there was a significant difference between genotypes in terms of most traits. The reaction of wheat genotypes was different in three experiments, but drought stress increased proline content and decreased chlorophyll content in all stresses. Chinese Spring genotype under normal irrigation conditions and stress in meiosis stage and 30% field capacity stress by storing more proline and chlorophyll and preventing the decomposition of these materials were identified as the most drought tolerant genotype. Osmoregulation has a positive relationship with grain yield and genotype Ehdaei 82 have the ability of osmoregulation and high grain yield under drought stress conditions in the meiotic stage. Under different water conditions, the higher Projected pollen grain area PEG 50% and the smaller Projected pollen grain area PEG 30%, Osmoregulation increases significantly.

The results showed that drought stress reduced the evaluated traits and genotype is more tolerant to drought that stores the highest content of proline and chlorophyll in leaves. Chinese Spring genotype was the most tolerant genotype with the highest content of proline and chlorophyll and high osmoregulation under normal irrigation conditions. Chinese Spring is in the group of genotype does not have the ability of osmoregulation and is suitable for dry conditions. This genotype is adapted to stress conditions by using other drought tolerance mechanisms and if improved for osmoregulation under stress conditions, it can be more adapted for cultivation in arid areas.