Tree nutrition and growth potential in grape in relation to xylem anatomy

In order to ascertain tree nutrition in grape cultivars with different growth potential in relation to xylem anatomy, exploration of the reasons for the differences of growth potential, six grape cultivars were selected as the plant materials. By paraffin method and hand sectioning, the xylem anatomical structure of roots and stems were comparatively studied, and morphological characteristics, carbon, nitrogen,phosphorus and potassium nutrition were determined. The results showed that xylem rate, vessel diameter,vessel frequency, total vessel area, the ratio of total vessel area and xylem area in growth vigorous cultivars were significantly higher than other cultivars, and growth weak cultivars were significantly lower. In growth vigorous cultivars, carbon content in root and stem was lower, significantly higher phosphorus content,significantly lower C/N, P/N and K/N in root and leaf than other cultivars. In growth weak cultivars, carbon content in root was higher than other cultivars; nitrogen content in root and leaf was significantly lower,significantly lower phosphorus and potassium contents in leaf, significantly lower K/N in stem; nitrogen content in stem was significantly higher, significantly higher C/N in root and leaf, significantly higher K/N and K/P in leaf. Thus, the cause of the growth potential difference among cultivars was due to differences of transporting ability in xylem vessel. The cultivars with transporting ability strong can supply a large number of nutrients to promote plant growth, and for the cultivars with transporting ability weak was just the opposite.