Leaf analysis survey of Pullar's Cling peach trees in northern Victoria: correlations between leaf nutrient status and tree performance in two years

Abstract

The N, P, K, Ca, and Mg contents of mid-shoot leaves of ten-year-old Pullar's Cling peach trees in the Goulburn Valley Irrigation Area, and the associated Murray Valley Irrigation Area were surveyed in 1964 and 1965. Leaves were sampled in mid summer from healthy trees in 73 orchards distributed over five major fruit-growing districts, and the results were related to tree yield (fruit number,) and vigour (butt circumference). Multiple regression analysis of the survey data showed that between 30 and 40 per cent of the total variation in tree yield over the two-year period was accounted for by variation in tree nutrient status. Such results clearly indicate the degree of influence that nutrition can play in the performance of mature peach trees in the field. As judged by published leaf nutrient standards for peach trees, about two-thirds of the peach orchards were of low nitrogen status in both seasons and this situation was reflected in tree yield. The low nitrogen status of the trees overall was a reflection of the low average amounts of nitrogenous fertilizer applied per tree per year. One-fifth of the orchards were of low phosphate status, but tree performance was not adversely affected as a result. In single years also, significant correlations were recorded between leaf K, leaf Ca, and tree performance, but, overall, these results were difficult to interpret meaningfully.