Identification And Screening Of Low Potassium Tolerant Soybean Popularized Varieties

Potassium deficiency was one of the important limiting factors to produce soybeans. A vermiculite culture experiment and solution irrigating were carried out simultaneously to approach the screening index for low K tolerant soybean varieties in preliminary experiment. 6 genotypes soybean had been adopted in present research work for investigating dry weight, fresh weight, the total proportion of leaves , chlorophyll content, K utilization efficiency, plant height and root-shoot ratio of soybean seedlings under different potassium supply in the nutrients solution. The differences of each index were compared in different genotypes so that the screening indexes for low K tolerant soybean varieties were confirmed and a method was founded to screen low K tolerant soybean varieties at seedling stage. 72 cotton varieties were screened in this method for low K tolerant. The relative physiological indexes were studied the difference of soybean K-efficient genotype and mechanism. The study was expected to provide basis in material and theory. The results were as follows:1. The differences of soybean varieties in potassium nutrition were significant. The seedling Fresh and dry weight of root, fresh and dry weight of shoot and K utilization efficiency were close related with K nutrition, the differences of them among different K concentrations and soybean varieties were significant so that these indexes were confirmed to screen soybean varieties.2. The differences and variations of soybean varieties in potassium nutrition were significant. The correlation analysis showed that a significant relationship existed between relative total dry weight and fresh weight, total leaf-areas, shoot dry weight, KUE at seedling stage. The relative shoot dry weight was regarded as a selection index of the response to K stress.3. According to these indices, 72 soybean varieties were divided into three types by cluster analysis, including high, low and intermediate potassium use efficiency genotypes..4. Among the tested varieties, Jidou8,Zhongke7412,Chengdou5 belonged to high potassium use efficiency. Zhonghuang4,Zhonghuang13,zhe98-14 belonged to low potassium use efficiency.5. The study deals with the effect of low potassium stress on protective enzyme system with different supplementation of potassium concentration in six soybean varieties (Jidou8,Zhongke7412,Chengdou5,Zhonghuang4,Zhonghuang13,zhe98-14)at seeding stages. The controlled plants under low K exhibited an increasing of SOD,POD and CAT activities in different degrees except content of MDA. So the difference of potassium nutrient effective types can be expressed by the difference of the protective enzyme systems. The high potassium use efficiency, genotype is distinct...