Evaluation of photosynthetic parameters in recombinant inbred linesof barley (Hordeum vulgare L.)‎ in relation to grain yield under water-stress conditions

الملخص EN

Drought stress is one of the major factors limiting barley yields in many developing countries worldwide.

A greenhouse experiment was conducted to study the photosynthetic parameters in relation to grain yield under water stress conditions on 40 recombinant inbred lines (RILs) developed from the cross between the cultivars Arta and Keel.

Plants were exposed to three water treatments during the period of grain filling until grain maturity as follow: (1) well-watered at 70% available water in the soil, (2) mild stress at 35% available water in the soil, and (3) severe stress at 10% available water in the soil.

All measurements were taken after 7 days of treatment.

Water stress conditions during grain filling significantly decreased photosynthesis (Pn) and grain yield (GY).

Well-watered plants of RILs and two parents had higher photosynthetic activity, (GY) and relative water content (RWC) than plants in mild and severe stress treatments; only intercellular CO2 concentration (Ci) for genotype Keel under mild stress treatment had smaller value comparing with well-watered and severe stressed plants.

The differences among genotypes (G), treatments (T) and (GxT) interaction were significant in all studied traits but were not significant in relative water content and grain yield when genotypes and treatments had been interacted.

In all studied traits there were significant differences among the three water stress treatment for the parameter Ci for mean of RILs and Ci, transpiration (E), stomatal conductance (gs) of Arta; In which differences between mild and severe stress conditions were not significant.

By increasing the severity and duration of drought stress, grain yield of RILs decreased 24% and 56% under mild and severe stress treatments respectively, while for the parents decreased 31% for both of them under mild stress and 61%, 46% in Arta and Keel respectively under sever stress condition.

Photosynthesis was found to be significantily correlated to grain yield under water stress conditions and the higher correlations were found for severe stress treatment.

Photosynthetic activity in relation to grain yield decreased by limiting the quantities of water supplied to plants.