Study On Growth And Phosphorus Efficiency Of Tissue Culture Plants Of Five Potato Cultivars In Phosphorus Deffiency

In order to study the effects of phosphorus deficiency to potato and the differences of phosphorus efficiency among different cultivars, growth state and the differences of phosphorus efficiency of new tissue culture plants were investigated when the shoots segment of tissue culture plants grown on normal phosphorus medium were transferred to normal phosphorus and low phosphorus medium respectively for 30days. Results showed that phosphorus deficiency changed morphology characters of potato plants obviously, and visible differences appeared in phosphorus efficiency.(1) Phosphorus deficiency treatment reduced root length of potato plants. The reduced extents of the five cultivars appeared obvious differences. Root length of Liangshu 97 reduced least; and that of Zhongnong VIII reduced mostly.Root numbers were increased except Liangshu 97, and that of 1-1035 increased mostly. Shoot lengths were all decreasing, that of Dabai reduced least, and that of Zhongnong VIII reduced mostly.(2) Fresh weight and dry weight reduced by phosphorus deficiency. Except Dabai and 1-1035, fresh weight of the five cultivars plants were decreased more than 50%. Dry weight of every plant of Dabai and 1-1035 decreased less than others, and their dry weight of phosphorus deficiency treatment were 87.36% and 88.24% of the normal phosphorus treatment, respectively. The characteristics of shoot dry weight, root dry weight and total dry weight all were: Yi Bujia , Zhongnong VIII and Liangshu97 affected greatly by phosphorus deficiency; While Dabai and 1-1035 affected less by phosphorus deficiency.The Root/Shoot ratios of Dabai and 1-1035 were increased , its of Zhongnong VIII and Liangshu97 were reduced, while it of Yi Bujia was unaltered.(3) After phosphorus deficiency treated, phosphorus accumulations of plants were greatly reduced. After phosphorus deficiency treated, the phosphorus accumulation of I-1035 was the most of the five cultivars.Physiological use efficiency of I-1035, Dabai and Liangshu 97 were increased greatly, that of Yi Bujia and Zhongnong VIII were decreased., compared with the normal phosphorustreatment. The physiological use efficiency of phosphorus of I-1035 and Dabai in phosphorus deficiency treatment was increased by 181.35% and 78.64%, respectively.After phosphorus deficiency treated, more phosphorus were translocated to root system of I-1035, Dabai , Liangshu 97 and Zhongnong VIII.The kinetic parameters of H2PO4- uptake by the five cultivars indicated that phosphorus deficiency increased Imax of the five cultivars, and excepted Zhongnong VIII, reduced Km and Cmin of other four cultivars. Compared with the normal phosphorus treatment, the affinity to H2PO4- (1/Km) of I-1035 was maximal, and the uptake critical concentration (Cmin) of H2PO4- of I-1035 was lowest.(4) A dendrogram of photo generated from morphological characteristics (length of root; root number and length of shoot) and phosphorus efficiency characteristics (plant fresh weight; plant dry weight; phosphorus accumulation and physiological use efficiency of phosphorus) results showed that phosphorus efficiency of I-1035 and Dabai are highest; and that of Yi Bujia and Zhongnong VIII are lowest; that of Liangshu97 is moderate.