The Ecological Characteristic And Its Application On Rice Grain Quality Formation In Different Cultivating Regions Of Jiangsu Province

In order to elucidate the basically ecological rule of rice grain quality formation in Jiangsu province, and consequently provide the basis for optimizing distributions of cultivars with superior grain quality and ecological regulation treatments, the effect of different seedtime, the latitude and climate characteristics on grain quality of different dominantly cultivated indica/japonica varieties in Jiangsu province were studied in four rice planting regions, Taihu district (Kunshan), the region of side of Yangzi River(Yangzhou), Lixiahe district (Jianhu) and Huaibei district (Donghai and Peixian), with five seedtime treatment. In the present study, the processing quality, appearance, cooking quality, RVA profile, as well as integrated quality index was assessed in the cultivars employed in different treatments. The main results were listed as following:1. In the condition of appropriate seedtime for all types of cultivars in each planting region, the middle japonica varieties (the early maturation middle japonica variety Yinjing 204, middle maturation middle japonica variety Zhendao 88, and late maturation middle japonica variety Wuyunjing 8), and the middle indica hybrid (Liangyoupeijiu) exhibited best processing and appearance quality in the region from Jianhu to Donghai experimental spots. However, the appearance quality of the middle maturation late japonica(Suxiangjing 1)cultivars decreased significantly as the latitude of experimental spots increasing. As the seedtime puts off, the processing quality of indica/japonica cultivars and appearance of japonica varieties exhibited the trend of turning inferior. In contrast, the appearance quality indica varieties turned better as the seedtime putting off.2.As the latitude of different rice planting region increases, the amylose contents of late maturation middle japonica and late japonica cultivars,as well as middle indica hybrid exhibited the trend of decreasing, resulting in the improvement of grain cooking quality. The early (middle) maturation middle japonica cultivars planted in the middle region og jiangsu Province, such as Lixiahe district, generally exhibited lower amylose content,resulting in good cooking quality. As the seedtime putting off, the amylose content exhibited the trend of increasing for all the type of cultivars. As for protein content index, no obvious rule was found across different experimental spots with different latitudes. However, there was a trend of increasing for protein content of japonica rice as the seedtime putting off, in contrast, the protein content of the middle indica hybrid exhibited the decreasing trend when the seedtime putting off. Moreover, the different effects of seedtime on protein content variation were observed depending on the different planting regions, the seedtime treatment has larger effect on protein content variation in Taihu, the side of Yangzi River and Lixiahe rice planting region, little effect in Huaibei region. Therefore, the type of varieties and the latitude of planting region should be put into the consideration for choosing appropriate seedtime, and consequently achieving the object of improving the protein content.3.In terms of RVA profile, Setback value of japonica cultivars increased with Peak viscosity decreasing when the seedtime putting off, reverse results were obtained for indica cultivars. When the latitude of planting region increasing, the RVA profile of early (middle) maturation middle japonica cultivars exhibited the trend of turning inferior. The middle maturation middle japonica varieties were propitious to be planted in the region between Yangzhou and Donghai; the late japonica varieties fit for planting in the south of the side of Yangzi River.4.The integrated quality index of the early maturation middle japonica varieties were stable, did not vary significantly across four planting place treatments. This index was the highest for middle japonica varieties and the middle indica hybrid planting in the region from Jianhu to Donghai, and exhibited better grain quality. The integrated quality index of the late japonica would decrease when the latitude of planting region increasing, and consequently grain quality turned inferior. The different types of cultivar responded differently on the temperature during the grain filling stage, as the integrated quality index was concerned.5.The analysis of the relationship between grain quality and climate factors showed that, the accumulative temperature during the grain filling stage was the primary factor affecting the milled rice rate; the average temperature of grain filling stage was significantly correlated with the appearance quality, amylose content, protein content, and RVA characteristics.â‘ The milled rice rate was negatively correlated linearly with the accumulative temperature during the grain filling stage for the middle(later) maturation middle japonica varieties; the relationship between milled rice rate and accumulative temperature for early maturation middle japonica varieties and middle indica hybrid could be depicted as conical curves with downward mouth.â‘¡The appearance quality of early maturation middle japonica was negatively correlated with temperature, while positive correlations were observed for middle maturation middle japonica, middle indica hybrid and middle maturation late japonica, however, conical curve relationship with downward mouth for late maturation middle japonica and early maturation late japonica varieties.â‘¢The relationship between the integrated quality index and the average temperature during the grain filling stage exhibited positive correlation for early maturation late japonica varieties were observed, and other varieties reverse negative correlation relationship were obtained.â‘£The average temperature during the grain filling stage was positively correlated with Peak Viscosity of RVA profile and gelatinization temperature, but negatively with Setback value.6.On the condition of safely production of different rice types in Jiangsu Province and their responding characteristics to light-temperature for high yield formation, and on the basis of characteristic of rice quality response to latitude of experimental spots, the rice planting region for different rice types could be divided into 4 types, feasible region, sub-feasible region, tolerable region, and unfitting region. As the good quality variety distribution in different planting region with different latitude in Jiangsu Province was concerned, the middle (late) maturation middle jaonica varieties should be dominant in major regions of the north of Jiangsu province, however, the early maturation middle japonica varieties fit for planting in the north of Xuzhou; In the middle region of Jiangsu province, late maturation middle japonica and early maturation late japonica are feasible; However, the early (middle) maturation late japonica varieties are fit for planting in the south of Jiangsu Province. The middle maturation middle indica varieties should be planted in the region N32o~N34o. On the basis of optimization of variety distribution, the cultivating system (including seedtime setting) to achieve good quality for different planting region also shoud be improvd. In Taihu rice planting region, it is fit to transplant large/middle seedling. In the side of Yangzi River region, early seed time is feasible for early maturation late japonica, appropriate seed time fit to late maturation middle japonica. In Lixiahe panting region, the middle maturation middle japonica should be seeded late combined with small /middle seedling transplanting, in contrast, large/middle seedling transplanting is fit for late maturation middle japonica. In Huaibei rice planting region, the two items of late seedtime and small/middle seedling transplanting are recommended.