Effects of irrigation methods and rice planting densities on yield and photosynthetic characteristics of matter production in cold area

Abstract: This research aims at discussing the influence of irrigation method and planting density on the rice yields in cold zone and production characteristics of photosynthetic substances, and the interaction effect, which has important meaning for the guidance of high yield of rice and high-efficiency cultivation. The experiment is carried out in the land for growing field crops, and takes Kendao 24 (A rice cultivar widely planted in rice production in china, which had high grain yield, extensive adaptability, and with growth duration of 130-135 days from sowing to maturity) as the experimental material. Deal the rice with three kind of irrigation method, heavy irrigation of alternation of wetting and drying (W1), light irrigation of alternation of wetting and drying (W2) and irrigation with shallow water(W3), and the planting distance respectively adopts 30 cm×10 cm (D1), 30 cm×12 cm (D2), and 30 cm×14 cm (D3). It will analyze the influence of the water and density on the yield formation of rice and production characteristics of photosynthetic substances. The results show that the overall effects of each way of irrigation on the dry matter accumulation, production of photosynthetic substance, yield components and yield present W2＞W3＞W1. W2 treatment has greatly improved the rice yield, and increases the 1000-grain weight and seed setting rate of rice. Compared with W3 and W1 treatment, the actual yield respectively increased by 5.05% and 27.89%; W2 treatment has effectively controlled the ineffective tillering, greatly improved percentage of earbearing tiller, and reduced the height of plant and length of the third and forth internode from the top while the growth speed of blade is slower than W3 treatment. Under all the conditions of density, the one resulting in the best effect in biological yield after head sprouting, dry matter transmission in the stem-sheath and the final grain yield is D2 treatment; the blade under D3 treatment grows faster than D2 and D1 treatment, and new leaves will grow. Under the interaction of different ways of irrigation and densities, each kind of way of irrigation and density treatment will cause significant or extremely significant interaction effect on the leaf age, number of stem and tiller, percentage of earbearing tiller, ratio of grain-leaf during heading period, dry matter accumulation, dry matter transmission in stem-sheath after heading sprouting and production of photosynthetic substance, yield components, and yield. The best effect appears under the light irrigation of alternation of wetting and drying and planting distance of 30 cm×10 cm（W2D1）. Compared with other treatments, it realizes the production increase by 5.0-8.5%, Yield increasing way of W2D1 treatment is achieved by the high ratio of grain-leaf, high leaf area index(LAI), more photosynthetic substance accumulation, high grain weight and harvest index, and the formation of high quality population; great dry matter accumulation at the late growth stage, high crop growth rate(CGR) and net assimilation rate(NAR), strong production capacity of photosynthetic substance, reasonable output and transmission of substances in stem-sheath, and great number of effective panicles, high 1000-grain weight and seed setting rate, which causing high grain yield. The comprehensive analysis shows that the treatments of light irrigation of alternation of wetting and drying and planting distance of 30 cm×10 cm are more suitable for the cultivation of rice in cold zone with high yield and high efficiency.