Effect of Defoliation and Drought Stress on Yield Components and Chlorophyll Content of Wheat

Abstract

In order to examine the effects of source restriction and drought stress on yield components, flag leaf chlorophyll content and Relative Water Content (RWC) of wheat cultivars, a greenhouse experiment was carried out at Shiraz University, Shiraz, Iran, during 2009-2010. The wheat cultivars including Shiraz, Bahar, Pishtaz, Sistan and Yavaros were sown in 5 kg plastic pots. The source manipulation treatments including control (C), defoliation of all leaves (D1), defoliation of all leaves except the flag leaf (D2) and defoliation of all leaves except the flag leaf and penultimate leaf (D3), were imposed at anthesis. Results showed that source restriction decreased number of grain per spike significantly in Shiraz cultivar under drought stress condition. Maximum 100-grain weight was observed in C treatment of Yavaros and Shiraz under well-watered condition. Among the defoliation treatments under drought stress condition, D2 in Pishtaz and D1 in Shiraz had the highest (3.66 g) and lowest (2.71 g) 100 grain weight, respectively. In all cultivars drought stress decreased main shoot yield significantly but in Pishtaz and Sistan decreasing rate was less than the other cultivars. RWC in Shiraz decreased sharply from 92.1% in well-watered to 66.7% (27.5% reduction) under drought stress at 10 DAA. After anthesis, Pishtaz and Sistan maintained higher content of flag leaf chlorophyll (from 49.4 to 56.8 SPAD unit) under drought stress condition. Generally, selection and culture of cultivars that had small responses to defoliation might be a useful strategy in yield improvement of wheat in areas where the water availability is low.

The Effect of Supplemental Irrigation on Canopy Temperature Depression, Chlorophyll Content, and Water Use Efficiency in Three Wheat (Triticum aestivum L. and T. durum Desf.) Varieties Grown in Dry Regions of Jordan

“…Our results were consistent with previous findings [73,83,84] that indicated that there was a linear, positive correlation between chlorophyll content and grain yield. They found that low chlorophyll content caused lower photosynthetic rate and consequently low grain yield.…”

“…In fact; TCC is an important factor in determining the photosynthetic rate and dry mater production [73][74][75]. The pronounced effect of water levels on TCC at post-anthesis might be due to the changes in photosynthetic rate, which is parallel to the change of chlorophyll content during grain filling [76].…”

Drought-induced changes in chlorophyll fluorescence, photosynthetic pigments, and thylakoid membrane proteins of Vigna radiata

“…This reduction may occur due to stress-induced impairment in pigment biosynthetic pathways or in pigment degradation. The decrease in Chl content is a commonly observed phenomenon under drought stress (Bijanzadeh & Emam 2010;Din et al 2011). More decrease in var.…”

Expression of an alfalfa (Medicago sativa L.) peroxidase gene in transgenic Arabidopsis thaliana enhances resistance to NaCl and H2O2

“…After treatment with H 2 O 2 for three days, MsPOD transgenic plants exhibited increased resistance to H 2 O 2 and leaf senescence was delayed ( Figure 4A). Chlorophyll content is also an important factor in the stress responses of plants; plants with high abiotic tolerance have a high chlorophyll content (Sanchez et al, 1983;Bijanzadeh and Emam 2010). We found no significant difference in chlorophyll content between transgenic and WT leaves without H 2 O 2 , but it significantly decreased when treated with H 2 O 2 .…”