| A field experiment was conducted on the Earth-Cumulic-Orthic Anthrosols in south Loess Plateau, to study the effect of nitrogen, cultivars and cultivation model on grain volume, 1000-grain weight and grain water content during the grain filling period of wheat.The results showed that grain volume accorded with quadratic equation of one variable, which increased quickly in the first stage of grain filling, then slowly increased to the maximum and then quickly decreased.In both the grain volume in different grain filling period and the maximum grain volume, Xiaoyan 22 was larger than Xiaoyan 503, the sequence of different cultivation models was: Harvest Rain Cultivation (HRC) >Plastic-film Mulching Cultivation (PMC) >Conventional Cultivation (CC) , the effect of nitrogen fertilizer on the grain volume wasn't significant, the time to maximum volume in different treatments was about 24.3～25.7 days and the difference wasn't significant.Grain weight change of different treatments showed a "S" curve and accorded with logistic growth model;grain weight of Xiaoyan 22 was larger than that of Xiaoyan 503;the sequence of grain weight in different cultivation models was: PMC>CC>HRC;nitrogen had positive effect on the maximum grain weight of Xiaoyan 22, but negative effect on Xiaoyan 503.In the whole, regards to grain filling rate, Xiaoyan 503 was larger than Xiaoyan 22, CC and HRC were larger than PMC, the nitrogen effect on grain filling rate and grain weight was inverse.The difference of grain weight in wheat cultivars was related with grain filling process, the difference between Xiaoyan 22 and Xiaoyan 503 wasn't significant in the early period, but the difference increased in the middle and late grain filling period, and grain weight of Xiaoyan 22 was significantly larger than that of Xiaoyan 503 in mature.The sequence of grain weight in mature and averagely in the whole gain filling process was: HRC>PMC>CC, which was different from the maximum grain weight.Water content decreased nearly lineally, water content of Xiaoyan 22 was significantly higher than that of Xiaoyan 503, but the effect of wheat cultivars and planting models weren't significantly different.There are linear or significantly linear relationships among grain volume, grain weight and water content. |