IMPACT OF DEFICIT IRRIGATION AT DIFFERENT GROWTH STAGES ON SOME SESAME VARIETIES IN UPPER EGYPT

Abstract

Two field experiments were carried out at Shandaweel during2005 and 2006 seasons to study the effect of deficit irrigation at different growth stages [i.e. Branching stage (I1), Flowering stage (I2), Capsule development stage (I3) and control (I4)] using four sesame varieties [i.e. Giza32 (V1), Toshky1 (V2), Shandaweel3 (V3) and Sohag1 (V4)]. The effect of the previously mentioned factor on yield, yield components, oil yield and some water relations were studied. Results indicated that number of capsules/ plant, length of fruiting zoon (cm), seed weight /plant (g), 1000-seed weight (g), seed yield (kg/ fed), and oil yield (kg/ fed) were significantly affected by the irrigation treatments. The highest values were obtained for I3 treatment except length of fruiting zoon (cm) which was increased for I4 treatment. Shandaweel3(V3) was superior in seed yield in 2005 season by 34.90, 7.90 and 10.30 % as compared with V1, V2 and V4, respectively. However, in 2006 the respective increase in seed yield reached about 54.30, 5.60 and 5.90 %. The best interaction effect was found for I3 with V3. Giza32 variety was superior in oleic acid and Sohag1 variety gave the maximum value in omega-6 as compared with the other varieties. Water consumptive use or evapotranspiration (ETcrop) in 2005 season was 2528, 2440, 2466 and 2932 m3/ fed for I1, I2, I3 and I4 treatments, respectively. The respective values in 2006 were 2639, 2549, 2565 and 3052 m3/ fed. The highest ETcrop was found for I4 in both seasons, while, I2 treatment showed the minimum value. With respect to varieties, values of ETcrop in 2005 were 2795, 2479, 2524 and 2569 m3/ fed, for V1, V2, V3 and V4, respectively. However, in 2006, the respective values were 2893, 2591, 2637 and 2684 m3/ fed. The variety of V1 registered the highest ETcrop in both seasons, however, V2 variety gave the lowest one followed by V3. The variety V2 saved irrigation water about 11.3, 1.9 and 3.5 % in 2005 and 10.4, 1.7 and 3.5 % in 2006 as compared with V1, V3 and V4, respectively. The interaction between I4 with V1 gave the highest ETcrop, however, the lowest ETcrop was found for the interaction of I2 with V2 in both seasons. Crop water productivity (CWP) was increased for I3 treatment compared with the other irrigation treatments under study. At the same time, V3 gave the highest CWP, while, V1 gave the lowest one in both studied seasons. The interaction between I4 with any variety registered minimum values of CWP. While, I3 with any variety gave maximum ones. The best interaction was found for I3 with V3. It can be concluded that subjecting sesame plants to long interval days between irrigations at capsule development stage encourage the plants to give more number of capsules, increase in seed weight/ plant and increase in seed yield/ fed accordingly. Shandaweel3 (V3) is more tolerant to water deficit as compared with the other varieties under study, while, Giza32is the most vulnerable. Also, flowering stage is more sensitive stage to water deficit, while, capsule development stage is more tolerant in the life of sesame plants.