Combined Soil and Foliar Nitrogen Fertilization Effects on Rainfed Almond Tree Performance

Abstract

Cultivation of almond in the Mediterranean region is traditionally done under rainfed conditions and poorly established cropping practices resulting in low yields. Despite the importance of nitrogen (N) fertilization to increase yield in cultivated species, this practice is usually neglected in rainfed managed almond orchards. Selection of the most appropriate rate and method of nitrogen (N) application are utmost factors to maximize almond yield in the considered conditions. Therefore, the aim of this study was to understand how soil and foliar N fertilization affect physiological and biochemical performance, almond yield, and fruit quality of almond trees grown under rainfed conditions. A 3-year experiment comprised four soil-applied N rates (0, 25, 50, and 100 kg ha −1) with and without 0.5% foliar N application of urea during the growing season, which was arranged in a randomized complete block design with three replications. Nitrogen soil fertilization did not influence the leaf gas exchange parameters and the content of photosynthetic pigments but significantly improved almond yield. There were no particular advantages in foliar fertilization. Soil application of small doses of fertilizer (e.g., 25 kg N ha −1) per year was optimal for maintaining appropriate physiological behavior of almond trees under the conditions in which the experiment was carried out, without compromise almond yield and fruit quality. Thus, the annual application at 25 kg N ha −1 enables substantial reduction of almond production costs being a positive contribution to environment-friendly farming practices.

Effects of Foliar Applications on Nutrient Concentrations of Kernel, Pomological Properties and Yield of 'Chandler' Walnut Variety at Different Altitudes

“…In Hazelnut B + Zn applications increased nut size and kernel weight (Horuz et al, 2021). In almond, soil and foliar N applications did not significantly affect the nut and kernel weight (Morais et al, 2020). A somewhat similar finding was obtained in this current study.…”

“…A similar result was achieved in this study. In the research by Morais et al, (2020) investigating the effects of combined soil and foliar nitrogen fertilization applications on almond trees, it was stated that N fertilization was not effective yield. On the contrary, in the current study, an increase in yield was recorded with foliar N application compared to the control in both locations and years.…”

Foliar Application of Boron Nanoencapsulated in Almond Trees Allows B Movement Within Tree and Implements Water Uptake and Transport Involving Aquaporins

“…In addition, if the water loss due to transpiration exceeds the amount of water taken up by the roots, the tree can exhibit stress responses, starting with stomatal closure. This will produce a reduction in gas exchange, with subsequent decreases in the rates of photosynthesis and the production of carbohydrates ( Morais et al, 2020 ), limiting the amount of energy available for vegetative growth, but also the transport of mineral nutrients, such as B, that move through the flow of water.…”

Effect of Foliar Fertilizing on the Yield of Some Almond Cultivars Grown in North Macedonia

“…On the other hand, a researcher found that application of N to the soil influenced the physiological performance of almond trees with positive implications on yield, while the supply of N via foliar fertilization (0.5% N applied three times during the growing season) did not provide encouraging results since it failed to improve the physiological behavior and yield of almond (Morais et al, 2020). Thus, other researcher explained that leaf sprays of N and B, including post-harvest applications, failed to increase crop nutritional status and kernel yield (Arrobas et al, 2019).…”