Effects Of Water Supplying On The Yield And Quality Of Rice In Cold Region

Water supplying was an important factor affected rice production. Elucidation of the effects of water supplying on yield and quality of rice would have great significance on conducting the rice production with high yield, good quality and high efficiency. Based on the pot and field experiments by rigorously controlling soil water potential(SWP) with tensionmeters, the effects of severe water stress on the characters of yield and quality were explicited, which could offer the theoretically reference for the selection of rice varieties with high yield, high quality and drought resistance; the cultivars applied in production were used as materials, the effects of whole growth period controlling irrigation and water supplying during different growth stages on growth and development, yield and quality of rice in cold region were studied, the index of irrigation for the production of rice in cold region was brought out, which provided the scicniific refcremce for the establishment of the technique regulation of high yield and high quality. The main results were as follows:1. Appraisal of drought resistance and screening its identification indexes of rice in cold regionThe germplasms of rice with longer days to heading, higher plant height, longer panicle length, heavier panicle weight, more numerous of primary rachis-branchesr, more numerous of second rachis-branches,more numerous of grain per panicle, higher kernel seting rate, higher biomass and higher harvest index had relatively higher drought resistance under water stress. The germplasms of rice with higher brown rice rate,milled rice rate and head rice rate, or with wider grain width, higher milled rice brightness, lower chalkiness rate and lower chalkiness degree, or with higher amylose content and lower fat content had relatively higher rice taste value under water stress. The germplasms of rice with less panicles per hill and more grain number per panicle had relatively higher head rice rate, L/W, amylose content under water stress. The germplasms of rice with higher kernel seting rate had relatively higher head rice rate and L/W under water stress. The germplasms of rice with heavier 1000-grain weight had relatively higher milled rice brightness and rice taste value under water stress. The germplasms of rice with higher economic yield had relatively higher L/W under water stress.The identical degree of drought index(DI) and drought coefficient(DC) was higher, and correlative coefficient was highest, both of them could be widely applied in practice. The identical degree of K and DC was very low, K could not be applied in practice alone. The identical degree of D and DC was higher, the correlative coefficient between them was far more higher than that of between any other single indicator and DC, D could more completely reflect drought resistance of rice, it could be widely applied in practice. The identical degree of QD and taste value drought coefficient(TDC) was higher, the correlative coefficient between them was far more higher than that of between any other single indicator and TDC, both of them could more completely reflect drought resistance of rice, they could be widely applied in practice.By means of these methods, when using DC, TDC and QD as indicators on drought resistance, seven varieties showed high resistance or medial resistance, which were Kendao 11, Wuyoudao 1, Songjing3,2010S-42,2010Y-88,2010Y-82 and 2010Y-100.2. Effect of water supplying during the stage before heading on yield and quality of rice in cold regionUnremitting irrigation at-18～-20kPa and-28～-30kPa of SWP were carried out during the stage before heading, Panicle length, panicle weight, primary rachis-branches number, second rachis-branches number, panicles per hill, grain number per panicle and 1000-grain weight of two varieties were significantly or very significantly decreased; the sensitivity degree ranked as follows:second rachis-branches number>primary rachis-branches number, grain number per panicle>panicles per hill>kernel seting rate>1000-grain weight, and the more water controlling intensity, the more decreasing rate; yield of two varieties were very significantly decreased, the reduction of Kendao 12 was greater than that of Kenjiandao 5, and the more water controlling intensity, the more reduction. Unremitting irrigation at-18～-20kPa and-28～-30kPa of SWP carried out during the stage before heading, was suitable for increasing head rice rate of Kenjiandao 5, Kendao 12 was opposited; grain length and grain width of brown rice,chalkiness rate chalkiness degree, amylose content and evaluation of white rice taste of two varieties were decreased; protein content of GEP of two varieties were enhanced.Intermittent irrigation at -8～-10kPa of SWP was carried out during the stage before heading, panicles per hill of two varieties was decreased, and the difference between treatment and CK was very significant in Kendao 12; grain number per panicle of two varieties were very significantly decreased; kernel seting rate and 1000-grain weight of two varieties were raised; yield of Kenjiandao 5 was increased, yield of Kendao 12 was decreased. Intermittent irrigation at -8～-10kPa of SWP carried out during the stage before heading, it was suitable for increasing head rice rate of Kenjiandao 5, was not suitable for increasing head rice rate of Kendao 12; L/W of two varieties were decreased; chalkiness rate, chalkiness degree and evaluation of white rice taste of superior grains of two varieties were raised, those of middle grains were decreased; protein content of GEP of two varieties were enhanced.Intermittent irrigation at -8～-10kPa of SWP was carried out during the stage before heading, water saving rates of two varieties were all above 20%; Unremitting irrigation at-18--20kPa and-28～-30kPa of SWP carried out during the stage before heading, water saving rates of two varieties were all above 30%; and water saving rate increased coupled with the raise of water controlling intensity. Intermittent irrigation at -8～-10kPa of SWP during the stage before heading could be used as irrigating index for producing high yield and high quality rice in cold region; it is unfavorable to carry out unremitting irrigation below -18～-20kPa of SWP during the stage before heading.3. Effect of water supplying during the stage before heading on yield and quality of rice in cold regionUnremitting irrigation at-18～-20kPa and-28～-30kPa of SWP were carried out during grain filling stage, panicles per hill of two varieties were decreased; panicle weight, kernel seting rate,1000-grain weight, biomass, harvest index and economic yield of two varieties were decreased, and the more water controlling intensity, the more economic yield decreasing. Unremitting irrigation at -18～-20kPa and -28～-30kPa of SWP were carried out during grain filling stage, which was suitable for increasing head rice rate of Kenjiandao 5, but was unsuitable for increasing head rice rate of Kendao 12; exterior quality became deteriorated; amylose content, peak viscosity value and evaluation of white rice taste of GEP of two varieties were reduced; hot paste viscosity and cool paste viscosity of GEP of two varieties were enhanced. It was unfavorable to carry out unremitting irrigation below -18～-20kPa of SWP during grain filling stage.Intermittent irrigation at -8～-10kPa of SWP was carried out during grain filling stage, panicle weight, kernel seting rate and harvest index of two varieties were increased; panicles per hill,1000-grain weight and biomass of two varieties were decreased. Intermittent irrigation at -8～-10kPa of SWP carried out during grain filling stage, was suitable for increasing head rice rate of Kenjiandao 5, was not suitable for increasing head rice rate of Kendao 12; chalkiness rate and chalkiness degree of GEP of Kenjiandao 5 were decreased, Kendao 12 were opposited; amylose content of GEP of Kenjiandao 5 was enhanced, Kendao 12 was opposited; evaluation of white rice taste of GEP of two varieties were reduced. Intermittent irrigation at -8～-10kPa of SWP carried out during grain filling stage, the yield of Kenjiandao 5 and Kendao 12 increased by 0.69% and 2.79%, respectively, as compared to CK, and there was no significance between the treatment and CK, but the water saving rate of treatment was lower by 17.06% than that of CK. Intermittent irrigation at -8～-10kPa of SWP during grain filling stage could be used as irrigating index for reducing the cost and increasing economic benefit of rice production in cold region.4. Effect of whole growth period controlling irrigation on yield and quality of rice in cold regionThe results of potted experiments has showed, intermittent irrigation at-8～-10kPa of SWP carried out from re-green to mature, the panicle weight, primary rachis-branches number and second rachis-branches number of two varieties were increased; panicles per hill of two varieties was decreased, and Kendao 12 reached the extremely significant level; grain number per panicle, kernel seting rate and harvest index of two varieties were increased; biomass and economic yield of Kenjiandao 5 was increased, those of Kendao 12 was decreased. Water controlling was not suitable for increasing head rice rate of two varieties; chalkiness rate and chalkiness degree of superior grains and middle grains of two varieties were raised respectively, those of inferior grains were decreased; protein content, globulin content,glutelin content, Gliadin content, peak viscosity value and the breakdown value of GEP of two varieties were increased; amylose content, setback value and evaluation of white rice taste of GEP of two varieties went down.The results of field experiments has showed, intermittent irrigation at-lOkPa of SWP carried out from re-green to mature was beneficial to improve the grain yield; it was beneficial to increase head rice rate, improve external quality and increase the evaluation of white rice taste; the rates of water saving were all above 20%, the effect of water saving was distinct. Whole growth period intermittent irrigation at-8～-10kPa of SWP could be used as irrigating index for producing high yield and high quality rice in cold region.