Comparative analysis on grain quality and yield of different panicle weight indica-japonica hybrid rice(Oryza sativa L.) cultivars

Indica-japonica hybrid rice(Oryza sativa L.) cultivars showed high yield potential and poor tasting quality when compared with common japonica rice cultivars. Large panicle is a prominent factor of high yield for indica-japonica hybrid rice cultivars, and the panicle weight varies greatly among different indica-japonica hybrid rice cultivars. It is important to research on yield and grain quality of different panicle weight indica-japonica hybrid rice cultivars. In this study, two different panicle types indica-japonica hybrid cultivars were used to research on the relation of yield and grain quality. The yields of two heavy panicle weights indica-japonica hybrid cultivars were significantly higher than that of two medium panicle weight rice cultivars. The cooking and eating quality and starch properties of different panicle type cultivars were evaluated. Yongyou 6715(medium panicle) and Yongyou 1852(heavy panicle) got the relatively higher cooking and eating quality. Rice cultivars with medium panicle weight had more large starch granules and higher relative crystallinity than cultivars with heavy panicle weight. Transition temperature and retrogradation enthalpy(ΔHret) of medium panicle type cultivars were significantly higher than that of heavy panicle type cultivars. There was no significant difference in amylose content among different panicle type cultivars. Protein content of heavy panicle type cultivar was higher than that of medium panicle type cultivar, and protein content is the main factor affect cooking and eating quality in this study. The cultivar Yongyou 6715 got the highest taste value with the lowest protein content. Thus, it is suggested that the emphasis on improving rice cooking and eating quality of indica-japonica hybrid rice cultivars is how to reduce the protein content in rice grain. According to the results of this study, medium panicle type with high grain weight is the desired panicle type for high quality indica-japonica hybrid rice breeding.

Comparison of grain yield and quality of different types of japonica rice cultivars in the northern Jiangsu plain,China

In recent years,an increasing number of different types of japonica rice cultivars have been released in the southern rice region of China.The grain yield and quality of these new cultivars showed significant differences in large scale planting.However,the causes of the differences remain little known.Therefore,three typical types of japonica rice cultivars were used in this study to investigate their grain yield and quality.A scanning calorimeter(DSC),X-ray powder diffractometer(XRD),rapid viscosity analyzer(RVA)and taste analyzer were used to evaluate the cooking and eating properties.The results showed that the yield of non-soft hybrid japonica rice cultivars was significantly higher than that of non-soft inbred japonica rice cultivars and soft inbred japonica rice cultivars.Soft inbred japonica rice cultivars had a low amylose content and moderate protein content,which are the main reasons for the superior cooking and eating quality.In addition,the relative crystallinity of soft inbred japonica rice cultivars was significantly higher than that of non-soft inbred and non-soft hybrid japonica rice cultivars,which is considered the major factor resulting in higher transition temperature and gelatinization enthalpy(ΔH_(gel)).Non-soft hybrid japonica rice cultivars had a higher number of large starch granules than soft inbred and non-soft inbred japonica rice cultivars.The setback value(SB)and breakdown value(BD),indirectly reflecting the cooking and eating quality of the three types of japonica rice cultivars,also confirmed that soft inbred japonica rice cultivars with a low SB value and a high BD value had better palatability than the other two types.This study provides guidance for future plantation of different types of japonica rice cultivars in large rice-producing areas.

缓控释氮肥对水稻生长发育及氮素利用的影响

速效氮肥对农业生产具有重要作用,但也存在用量大、损失途径多、损失量高等特点,造成了一系列环境问题。相较而言缓控释氮肥养分释放缓慢,可减少氮素损失,提高氮肥利用效率,应用于水稻也能够一定程度地增加产量。施用缓控释氮肥对水稻的影响是全方面的,从稻田氮素损失、氮素吸收利用到产量形成均产生不同的影响。本文概述了缓控释氮肥对稻田氮素损失、水稻氮素利用、器官生长、群体变化及产量形成的影响,探讨了水稻上施用缓控释氮肥产生不同效应的原因,阐述了缓控释氮肥在水稻上应用存在的问题及改进措施。

凹土对甘薯植株生长和生理代谢的影响

通过盆栽试验研究在盐、干旱胁迫下外施凹土对甘薯幼苗生长和生理代谢的影响。在200 mmol/L Na Cl胁迫、干旱胁迫处理下,外施凹土添加到土壤中能够显著增强甘薯的耐盐性和抗旱性;酶活性测定结果显示,外施凹土显著增加盐、干旱胁迫下超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)和过氧化酶(POD)的活性;物质含量测定结果显示,在盐、干旱胁迫下外施凹土显著增加甘薯的脯氨酸、相对水、可溶性糖和叶绿素的含量,显著降低丙二醛(MDA)和过氧化氢(H_2O_2)的含量。结果表明,凹土可以缓解盐、干旱胁迫对甘薯造成的伤害,从而增强甘薯植株的耐盐性和抗旱性。