The role of osmotic compounds on water relations of barley genotypes under drought stress

Drought decreases plant growth/productivity, by cell division and expansion thus cell water component reducing. In this study, tolerant (N and M), semi-tolerant (W) and sensitive (K) genotypes were investigated in a randomized complete block based split-plot experiment in 2 irrigation regimes (rain-fed and complimentary) at Dryland Agricultural Research Institute, Maragheh. Relative water content did not change significantly in drought. Stress caused a significant decrease in SPAD, total, a, b, a/b chlorophyll and carotenoids achieving their highest content in W, M and N. Due to elevated cell concentration, the osmotic potential was higher during water deficit. Maximum osmotic potential and osmotic adjustment were related to Flag leaf of M, W and second leaf of N and K. In the tolerant and semi-tolerant cultivars, Leaf and stem soluble-carbohydrate increased at the second stage and then reduced, due to transportation to spike, under both regimes. However, K had a decreasing trend in both conditions. In drought condition, M contained the most soluble-carbohydrate. Sucrose increased in drought, particularly in M. In all cultivars,there was a decreasing trend during the sampling stage in the stem. Maximum glucose content occurred in leaves of W and spikes of K and M during irrigation regime and W spikes during drought. Fructose decreased in all genotypes in both irrigating regimes. M and N showed the highest amount of fructose at second harvest during a deficit. In brief, accumulation of cell soluble materials is an effective approach to increase plant drought tolerance which can be used in breeding programs.

کلیدواژه ها:

Chlorophyll ، Carotenoids ، Osmotic potential ، Soluble-carbohydrate ، Drought stress