Effects Of Seeding Date On Grain Yield And Functional Characteristics Of Low Glutelin Rice

Field experiment involving three low-glutelin rice cultivars and five seeding date treatments was carried out in 2012 to determine the effects of seeding date on grain yield, rice quality and protein fractions accumulation and to define the effects of climatic factors during different growth stage on grain yield, climatic factors during filling stage on rice quality and daily mean temperature in different period of time during filling stage on the prolamin and glutelin accumulation. Theoretical basis and technical reference were provided for high yield and quality of low glutelin rice cultivars. Our results showed as following:1. Effects of climatic factors on grain yield of low glutelin rice cultivars. W3660, W1721 and W1240 reached maximum grain yield by seeding at May 20, May 30 and May 20, respectively. Thousand seed weight and setting percentage were low in three low-glutelin rice cultivars when grain yield reached maximum, while the number of grain per panicle or the number of panicles was significantly higher than other treatments. Further, number of grain per panicle and number of panicles were greatly influenced by climatic factors, and thousand seed weight and setting percentage were influenced slightly. Climatic factors in vegetative and reproductive stage when number of panicles and number of grain per panicle were produced played a dominant role in grain yield. Lower accumulated temperature and daily mean solar radiation in vegetative stage, higher daily mean air temperature and daily mean solar radiation in reproductive stage were conductive to the formation of the panicles, besides higher accumulated temperature and lower daily mean rainfall werehelpful to obtain higher number of grain per panicle.2. Effects of climatic factors on rice quality of low glutelin rice cultivars. Chalk degree was sensitive to climate conditions changes, grain length and width were more stable, and head rice rate, protein content and amylose content were mediate. By comparison to daily mean realtive humidity and daily mean rainfall, average daily temperature in filling stage had the greatest influence on rice quality, followed by daily mean solar radiation, daily mean temperature difference and accumulated temperature. It was found by investigating different time period during 1-30d after heading that the climatic factors during 11-20d were significantly and positively correlated with the head rice rate, protein content and amylose content. Higher daily mean temperature and effective accumulated temperature during 11-20d in filling stage were not conductive to improve the head rice rate, on the contrary, higher daily mean temperature was helpful to improve the protein content and amylose content in low-glutelin rice cultivars.3. Effects of climatic factors on functional characteristic of low glutelin rice cultivars. Average daily temperature in filling stage had the greatest influence on gultelin content, followed by daily mean solar radiation, effective accumulated temperature and daily mean temperature difference. The main reason why the content of glutelin in three low-glutelin rice cultivars did not decrease as the seeding date delaying was the influence of temperature in different time docket were diverse. Prolamin accumulated quickly and largely in 1-20d in W3660, and 1-20d in W1721 and W1240, while glutelin accumulated quickly and largely in 1-20d in W3660 and W1721, and in 1-15d in W1240. Daily mean air temperature in later period of filling stage had a slight influence on glutelin content, while glutelin content were determined by whole filling stage. Relatively low daily mean temperature during early period of filling stage and relatively high daily mean temperature during later period of filling stage were conductive to prolamin accumulation.In the early stage of filling stage the content of glutelin in three low-glutelin rice cultivars were characterized by that in a certain temperature degree the higher the average daily air temperature was, the more the glutelin accumulated, when average daily temperature was higher than a certain value the glutelin content then decreased. Higher average daily air temperature in later period of filling stage was conductive to glutelin accumulation in W3660 and W1721, while, in W1240, it was opposite.