A study on physiological attributes and grain yield of sesame (Sesamum indicum L.) cultivars under different soil moisture regimes

Sesame could be an appropriate oilseed crop for water limited environments. This research was aimed at studying growth, leaf chlorophyll fluorescence, proline content, yield and yield components of sesame cultivars under different moisture regimes. A 4-replicate split plot RCBD field experiment was conducted at the Lavark Research Farm, College of Agriculture, Isfahan University of Technology, Isfahan, Iran in 2007. Three levels of irrigation consisting I1 = control (no water deficit), I2 = moderate water deficit and I3 = severe water deficit, representing irrigation after 75, 110 and 145 mm evaporation from the standard Class A Pan, respectively, served as main plots. Four sesame genotypes consisting ‘Non Branching Naz’, ‘Yekta’, ‘Varamin’ and ‘Oltan’ were considered as sub plots. Irrigation regimes and cultivars differed in terms of Fm at grain filling stage, though they did not differ in terms of leaf chlorophyll content and Fv/Fm. The latter trait decreased non-significantly from 0.81 at the I1 to 0.77 at the I3 level of irrigation. Leaf proline content increased from 3.5 at I1 to 8.6 mgg-1 at the I3 level of irrigation. Severe water deficit decreased LAI, pod/plant, seed/pod, grain yield and dry matter by 55, 42, 37, 48 and 49 percent, respectively. Severe water deficit led to a significant decrease in grain yield from 1212 to 625 kg/ha. It seems that water deficit affects sesame growth and grain yield significantly and this negative effect is mainly through a reduction in the photosynthetic surfaces, rather than a decrease in the maximum of quantum efficiency for photosystem II of the present genotypes. Yekta and Varamin sesame were more productive compared to the rest of cultivars.