Screening Of K-deficit Tolerant Offspring From Different Rice Varieties Introduced DNA Of K-sufficiency Plant And Comparative Study Of Their K Nutrition Trait

DNA from K-rich plants Alternanthera philoxeroides and Phytolaoca esculenta Van Houtt were introduced into different rice varieties MW, Zaoxian 91-L, Guibao 8, Jing 187 and Jing 85-5. From their offspring 32 plants were chosen as experimental materials for screening low-K tolerant plants at seedling stages by solution culture. The results show that the suitable screening time is 3-leaves stage and the suitable screening K concentration 1.0 mmol/L. Ten plants were found strong tolerant to low K. Their K influx and H efflux were much higher than those of recipients and similar with standard variety Minghui 63. The tolerance to low K was further confirmed by measuring their height, dry weight of shoots and roots of the 10 plants at tillering stage under normal and low K levels.Comparative study of K nutrition characteristics between the 10 K deficient tolerant plants and 5 recipients was carried out in solution culture. Two levels of K supply (Kl: 40mg/L, K2: 3mg/L) were set up. Significant difference has been observed among these materials under low K. In spite of K variation the 10 low K tolerant plants showed little change in their growth. Five recipients, however, response significantly different under two K levels. Fresh weight, relative dry weight, root length, root dry weight and root activity of the 10 plants was higher than their recipients' respectively. K content and K utilization efficiency also showed the same trend. Plants A-l and B-12 were typically tolerant to low K condition.