Abstract:

Xiangyang district is an important granary in Hubei Province, rice and wheat rotation is the main cultivation mode in the area. Grain drop and spike rot had appeared in rice production after using rice seeds successively reserved by farmers themselves. In order to explore the cause of poor growth of rice, samples on the spot for investigation were taken and analysis of these phenomena was carried out. Through the method of morphological characteristics observation and molecular biology identification, using the rice ‘Huanghuazhan’ purchased from the market as control, 41 pairs of rice molecular specific markers were detected, the virulence of chemical agents to the isolated pathogens was determined by the growth rate method. Four species of pathogens were isolated from withered rod and rotten ears including Nigrospora oryzae, Fusarium proliferatum, Fusarium equiseti, Fusarium graminearum; the seeds from farmers which were successively reserved for 6 years had no heteromorphosis, but rice grains harvested in the no-tillage rice field had 12 fingerprints different from the contrast. It indicated that the seeds of ‘Huanghuazhan’ preserved by farmers for 6 years had variation in field growth; Zoloether·propineb 70% WG and Kresoxim-methyl·epoxiconazole 23% SC could inhibit the growth of all pathomycetes. Continuous seed retention for many years will cause the vitality of rice seeds to decay, resulting in weak growth of rice in the field, vulnerable to disease invasion, and abnormal growth. Correctly using seeds, scientific management and the control of suitable agrochemicals are important measures to ensure the safe production of rice.

Key words: Xiangyang wheat-rice rotation area, rice, self-retained seed, seed falling in advance, rice spikelet rot disease