Effect of Different Water-controlled Periods and Intensity on Grain Filling Characteristics of Rice

To study grain-filling characteristics of rice in different water-controlled periods and intensity,superior and inferior grains characteristics of two rice cultivars( Shangyu 397 and Suijing 3) was comparatively analyzed with Richards equation W = A /( 1 + BeKt)1 / Nand three water-controlled periods,i. e. 1- 10,11- 20,21- 30 days after heading and two types of intensity,i. e. at- 30- 35,- 60- 65 k Pa of soil water potential. The results showed that 1- 10 d after heading water-controlled treatment,regardless of water-controlled intensity,significantly reduced the 1000-grain weight of total grains,superior grains and inferior grains of two varieties,11- 20,20- 30 d after heading water-controlled treatment had little effect on 1000-grain weight,and had even increasing trend. Compared with 0 k Pa( CK) soil water potential,when the soil water potential of- 30- 35 k Pa,1- 10 d after heading water-controlled treatment made initial grain-filling potential of superior grain of two rice varieties reduced,filling rate changed little,the grain-filling time and contribution rate of the early stage prolonged,and the grain-filling time and contribution rate of the middle and late stage shortened. The impact on the inferior grain varies with species.11- 20 dafter heading water-controlled treatment had significant effect on superior and inferior grains characteristics of two rice cultivars. Superior and inferior grains characteristics of Shangyu 397 had consistent performance. Fillingrate was significantly decreased,the grain-filling time and contribution rate of the early stage was shortened,and the grain-filling time and contribution rate of the middle and late stage was prolonged. Superior grains characteristics of Suijing 3 showed the opposite of inferior grains. 21- 30 d after heading water-controlled treatment had little effect on superior grains filling characteristics of the two varieties,yet had greater effect on inferior grains filling characteristics. When water-controlled intensity increased,effect of 1- 10 day after heading water-controlled treatment on superior grains and inferior grains filling characteristics grains of the two varieties was greater than that of other treatments.