Study On Differences In Response Of Different Potato Varieties To Deficient Potassium

In order to learn the differences in low-K⁺-tolerance of different variety of potato, priliminary study was focused on the selection of suitable potassium concentration for screening K⁺-deficit tolerant potato varieties, the difference of potato in response to deficient potassium, and the differences of physiological and biochemical characteristics in different low-K⁺- tolerant potato varieties.1. In our study, we meared the of shoot length, root numbers, dry weight of root and dry weight of shoot per plant of eight potato cultivars treated with four levels of low potassium for 30 days. The result indicated that the differences in four parameters of varieties were significant, the higher potassium level, and the higher the values. The variation coefficients of all the four parameters were highest at 1 × 10^-3 mol/L K. Therefore 1×10^-3 mol/L was the suitable potassium level to screen low-K⁺-tolerant potato varieties.2. The result showed that shoot length, dry weight of root and dry weight of shoot per plant of ten potato cultivars decreased significantly at low potassium culture medium. And there were significant differences in dry weight per plant in varieties under low potassium. The ten varieties were classfied by the dendrogram of cluster analysis of the ratios of dry weight of root, dry weight of shoot and length of shoot per plant and the analysis of dry weight per plant under low potassium. The result showed that Gaoyuanqihao was low-K⁺-tolerant potato variety, Daxiyang and 9201 were non-low- K⁺-tolerant potato varieties.3. The differences of dry weight of root and shoot, potassium gross in root and shoot, potassium gross per plant, potassium content in root and shoot, chlorophyll content in shoot, chlorophyll gross per plant and so on were measured in low-K⁺-tolerant variety and non-low- K⁺-tolerant varieties. The results were as follows:(1) The ratio of dry weight of root to shoot of low-K⁺- tolerant variety decreased more significantly than that of non-low- K⁺-tolerant varieties under low potassium.(2) Potassium grosses in root or shoot per plant of non-low- K⁺-tolerant decreased more significantly than low-K⁺-tolerant variety under low potassium. And potassium grosses in root or shoot has significant positive correlations with dry weight of root or shoot.(3) Percentages of potassium gross in shoot per plant were higher than those in root under low potassium and normal potassium. Distributing ratio of potassium gross per plant in root decreased under low potassium. And distributing ratio of low-K+-tolerant variety was lower.(4) Chlorophyll gross per plant of low-K+-tolerant variety was higher than non-low-K+-tolerant varieties under low potassium and normal potassium. And chlorophyll gross has significant positive correlations with potassium gross in shoot or potassium gross per plant.(5) Contents of soluble sugars in root and shoot of every variety decreased under low potassium. And contents of soluble sugar in root and shoot of low-K+-tolerant variety was lower than non-low- K+-tolerant varieties under low potassium and normal potassium.(6) Under low potassium, activity of POD in root of every variety decreased. Activity of POD in shoot of low-K+-tolerant variety decreased and non-low- K+-tolerant varieties increased under low potassium. Under low potassium and normal potassium, activity of POD in root or shoot of K+-deficit tolerant variety were lower than non-low- K+-tolerant varieties; and they were affected significantly by low potassium.(7) Content of MDA in leaves of every variety was not influenced significantly by low potassium, and there were no significant differences of contents of MDA in low-K+-tolerant variety and non-low- K+-tolerant varieties.