Effect of irrigation schedule on growth of saline-alkali tolerant rice

【Objective】 Soil salinity and alkalinity is the main soil stress facing crop production in Northwestern China. Developing crop varieties resistant to salinity and alkalinity is a way to developing sustainable agriculture in this region. This paper presents an experimental study on the impact of irrigation amount and schedule on growth of saline-alkali tolerant rice in Northern Yinchuan in Ningxia Hui Autonomous Region. 【Method】 The experiments used Ningjing 56 (NJ56) and Jijing 105 (JJ105) - two saline-alkali tolerant rice varieties commonly grown in this region - as model plants. There were four irrigation treatments (W1-W4). The irrigation amount for W1-W4 was: 3 000, 2 700, 2 400 m3/hm2 and 2 100 m3/hm2 before seedling emergence; 1 050, 1 650, 1 800 m3/hm2 and 1 500 m3/hm2 at the seedling stage; 1 800, 1 200, 1 050 m3/hm2 and 2 100 m3/hm2 at the tillering stage, 2 100, 1 500, 1 800 m3/hm2 and 1 350 m3/hm2 at the jointing stage; 1 350, 1 800, 1 050 m3/hm2 and 500 m3/hm2 at the heading stage; 900, 1350, 2 100 m3/hm2 and 1 650 m3/hm2 at grain filling stage, respectively. The effect of each irrigation treatment on growth, yield and quality of the rice were measured in the experiment, from which we calculated the optimal irrigation for each rice variety. 【Result】 ① For JJ105, the percentage of chalky grain and the degree of chalkiness were the highest in W1, reaching 68.67% and 19.30%, respectively; the seedling emergence was the highest in W2, reaching 84.47%. W3 gave the highest milling rate, protein content and gel consistency, reaching 81.76%, 9.40%, 9.13, respectively. ② For NJ56, W1 gave the highest tillering and panicle formation rate, grain yield, irrigation water use efficiency, and water and amylose content in the grains, reaching 75.67%, 10 388.78 kg/hm2, 101.85%, 10.50% and 20.07%, respectively; the 1000-grain weight was the highest in W3, reaching 24.83 g; W4 gave the highest spike length, and grain weight per spike, reaching 21.35 cm and 2.81 g, respectively; the alkali elimination value in W4 was 7 for the two varieties. 【Conclusion】 There were significant differences between the two varieties in their response to irrigation treatments. Overall, NJ56 grew better and the associated optimal irrigation for it is W4.