Zhu Qing-sen

Symptom of the Shrunk-Grain Panicle and the Change Characteristics in Its Grain

Abstract Over the past two years, an abnormal growth phenomenon called shrunk-grain panicle has occurred in a large area in Jiangsu Province of China. The phenomenon is described in details by figures and characters in this article. The method with a japonica rice Wuyujing 3 as the experimental material, the characteristics of grain morphology distribution and the grain weight were studied. Normal and shrunk-grain panicles were sampled from several representative areas. The length, width, and weight of the normal grains were distributed as regular, continuous, and single peaks. Plant growth typically had a right-leaning tendency. On the contrary, the distribution of the grain morphology and weight were irregular and nearly double that of the shrunk-grain panicle. The proportion of the cumulative distribution in the two kinds of peaks was closely related to the degree of shrunk-grain panicle. The article discusses the phenomenons symptoms, problems, and diagnosis.

Growth and development characteristics of super-high-yielding mid-season japonica rice

Rice is one of the most important food crops in China. The realization of the super-high-yielding (SHY) type has great significance in ensuring food security in this country. This study investigated the growth and development characteristics of the super-high-yielding rice (grain yield > 11 t/hm2). Four mid-season japonica rice cultivars (including lines): Lianjiajing 2, Huajing 5, 0026 and 9823, were grown in the paddy field. Growth analysis was performed during the growth period, and yield components were determined at maturity. Results showed that SHY rice had more sipkelets per panicle and higher filled-grain percentage than the high-yielding rice (CK, grain yield 8.98–9.16 t/hm2). There was no significant difference in the 1 000-grain weight between the super-high-yielding and the CK. Super-high-yield rice exhibited fewer tillers at the early growth stage (from transplanting to jointing), with a higher ratio of productive tillers to total tillers, when compared with the CK. The leaf area index (LAI), photosynthetic potential and dry matter accumulation were lower for the SHY rice than those for the CK at the early growth stage, and the differences were not significant between the two rice types at heading, but were greater in the former than the latter after heading. The root-shoot ratio at each growth stage, root bleedings from heading to maturity, grain-leaf ratio, translocation percentage of the matter from stems and sheaths and harvest index of super-high-yielding rice were greater than those of CK. The indexes for the growth and development of SHY mid-season rice population were suggested, i.e. total spikelets > 4.5 × 104/m2, filled-grain percentage > 90%, 1 000-grain weight > 26 g; ratio of productive tillers > 80%, leaf area index at heading 7.5–8.0, photosynthetic potential during the whole growth period > 5 × 106 m2·d/hm2, total dry matter weight at maturity > 22 t/hm2, harvest index > 0.51; grain-leaf ratio (number of spikelets per cm2 leaf area) > 0.58; root-shoot ratio at heading > 0.25 and amount of root exudates > 5 g/m2·h. The regulation approaches and key cultivation techniques for raising the super-high-yielding population were also discussed.