Prognosis of leaf chlorosis in Catherina peaches based on the mineral composition of flowers

Resumen

The peach tree is one of the fruit species with the highest production and area cultivated in Spain, which rootstock show a marked influence on the mineral content of leaves and consequently on chlorosis. The nutritional diagnosis of the peach tree, based on the mineral analysis of leaves, is often late for in-season amendments, while leaf diagnosis based either on photosynthetic activity (non-destructive) or on iron chlorosis is always late and in many cases imprecise. Previous work from Aula Dei (CSIC) has established the possibility and efficiency of making a mineral prognosis of leafs based on the mineral composition of flowers not only in peaches but in pear and cherry trees. This current work aims to go further in non-destructive prognosis by selecting key features from RGB images and validating them in a set of 300 photographs. The test was carried out in a plot located in the Experimental Station of Aula Dei (CSIC), the soil of the plot being heavy and calcareous. Six plumxpeach trees have been used determining the foliar and floral mineral concentration on flower at full blossom (FB), and corresponding leaf samples at 120 days aFB. The ions in flowers and leaves were determined by plasma-mass spectroscopy, while the measurement of the photosynthetic activity of the leaves and their mineral composition was carried out 120 days after full flowering using a SPAD meter. The SPAD used as a reference for the identification of chlorosis in peach leaf appears correlated with several leaf minerals: Ca, S, Fe, Cu and Sr, restricted to Ca and Sr when compared with the mineral composition in flowers. The mineral composition of the flowers allows anticipating extreme cases of chlorosis based on Sr and Ca levels, while the methodology developed based on RGB images shows promising results and is still ongoing