Effect of water stress on growth, productivity and water expense efficiency of summer rice

Abstract

A field study was carried out during 1997 and 1998 cropping seasons on a tine loamy (Typic Ustochrept) soil type, to assess the performance of  IET 4786' summer rice (Oryza sativa L.) under stressed (intermittent ponding) and non-stressed (continuous ponding) situations. In case of intermittent ponding, irrigation was given when soilmoisture tension at 20 cm depth attained the suction value of 0-02 M Pa. Entire irrigation period was divided into 3 stages, ie early [11 to 30 days after transplanting (DAT), middle (31 to 60 DAT) and late (61 to 80 DAT) stages. Intermittent ponding was imposed at single, ie in early (I 2 ) middle (I 3 ) and late (I 4 ) stage or at two stges, ie early plus middle (I 5 ) early and late (I 6 ) and middle plus late (I 7 ) stages. Besides, there were 2 more irrigation regimes, ie continuous ponding was maintained throughout the entire irrigation period (I 1 1) and intermittent ponding was maintained during the entire irrigation period (I g ). The highest grain yield (6.79 Mg ha) was attained under I 1 , followed by yield of 6.71 Mg ha under 12, Grain yeild mllrkedly decreased under 1 3 , I 5 , 1 7 regimes and it attained lowest value (5.37 Mg ha) under Is. Water expense efficiency (W ee ) value attained the lowest level (5.26 kg/halmm) under 17 regime. While it was highest (5.99 kg/halmm) under I 8 regime and this W ee value was 8.7% higher over I 1 . Though grain yield attained lowest value under 18 but minimum level of water expense value (910.4 mm) responsible towards greater W ee value (5.71 kg/ha/mm) under this treatment.