Nutritional standards through Integrated Differential Diagnosis (IDD) in pomegranate (Punica granatum L.)

The foliar analysis is a useful tool to detect the nutritional status of plants, predict future problems in the reproductive cycles of fruit production and implement preventive and corrective measures to achieve a mineral balance in fruit trees, obtaining higher productivity. There is little information available on nutrient sufficiency ranges in pomegranate leaf and the literature reported differs due to diverse cultivation practices, cultivars, and agroecological conditions. Therefore, the objective of this work was to determine the mineral content of ‘Wonderful’ pomegranate leaves for each the nutritional elements and the cation balance, and to establish the nutritional standards using Integrated Differential Diagnosis (IDD). The mineral content of the pomegranate leaves was determined and based on the results, nutritional standards for macro elements, cation balance and microelements were generated through the IDD, which evaluate whether there are mineral and/or physiological imbalances. The macro elements in the cultivation of the pomegranate were the following: NO3 3747.5 µg g-1, Total Nitrogen 1.35%, P 0.14%, K 0.88%, Ca 1.65%, Mg 0.19%, Na 0.006%. For the cation balance, the optimal values ​​were: (Ca+Mg)/K 4.48 mEq 100 g-1, Ca/(K+Mg) 2.13 mEq 100 g-1, Mg/(K+Ca) 0.16 mEq 100 g-1, Ca/Mg 5.06 mEq 100 g-1, K/Mg 1.36 mEq 100 g-1. Finally, the optimal values ​​for the microelements were: Fe 59.5 µg g-1, Mn 31.4 µg g-1, Zn 6.3 µg g-1, Cu 6.1 µg g-1. The values ​​obtained for the micro and macro elements were like those reported. In the case of cation balance and foliar nitrate content, they have not been previously reported. The IDD is a promising and effective auxiliary tool to characterize the nutritional status of pomegranate trees and, in turn, an alternative to conventional methods of nutritional diagnosis with the advantage of establishing a nutritional deficiency (soil-plant relationship) or a physiological imbalance (relation plant - climate) for this crop.