Browsing by Author "Wolf, Anchen"

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    The effect of foliar micronutrient applications on nutrient use efficiency in tomatoes
    (Stellenbosch : Stellenbosch University, 2024-03) Wolf, Anchen; Kempen, Estelle; Stellenbosch University. Faculty of AgriSciences. Dept. of Agronomy.
    ENGLISH ABSTRACT: Plant nutrient management through the application of a balanced nutrient solution is critical for the success of crops in intensive production systems. Over-application or unbalanced applications however can result in wasted resources and environmental pollution. This study explores the impact of micronutrient foliar applications of silicon (Si) and boron (B) on the post-harvest yield and quality of two tomato varieties in a fertigation system where the calcium (Ca²⁺) and potassium (K⁺) application ratio is adjusted. Using these fertigation systems, the objective is to determine whether the nutrient use efficiency (NUE) can be improved for tomato production systems with the respective treatments. The study was conducted in a greenhouse on the Welgevallen Experimental Farm in Stellenbosch, Western Cape. Two varieties of tomatoes were used, Floradade and Solarino RZ F1 (72-150). Seedlings were planted into 20 L bags with coconut peat as the growing medium. The trial comprised of four treatments with an open-hydroponic system where a foliar feed of Si, B, or a combination of the two was applied in conjunction with a fertigation solution where the Ca²⁺ % was adjusted or followed standard recommendations. This adjusted solution maintained an EC of 2mS.cm⁻¹ where the Ca:K and Ca:Mg ratios were changed with reduced Ca²⁺ and increased K⁺ and Mg²⁺, whereas the standard solution had ratios according to the Steiner solution concentrations. Analysis of the data collected during the trial, both developmental and post-harvest, was done using R (R Core Team, 2023) and STATISTICA Version 13.3 (TIBCO Soft Inc. 2016) for statistical software. A full nutrient analysis was also conducted on the fruits. Standard fertigation treatments, specifically treatment 2 with the added Si foliar feed had the most significant effect on the vegetative growth parameters. The reduced fertigation treatments had a less significant impact on these parameters, although the rate of Ca²⁺ supplied to tomatoes can be reduced if managed correctly, and if amendments of B and Si are given. The adjusted Ca²⁺ % reported an 18% increase in NUE for the marketable weight of the harvested product, and an 8% increase for the marketable weight of all the treatments combined, allowing growers to receive a larger percentage of marketable product at the same input cost and volume of nutrients compared to the standard fertigation treatments. It is confirmed that the NUE can be improved in hydroponic tomato production where Si and B are applied as foliar feed substitutes for Ca²⁺ without compromising the quality and post-harvest shelf- life of tomatoes. The reduction of Ca²⁺ % in the fertigation and the addition of Si and B did not compete with standard fertigation treatments. This reduction of the input, however, allowed for an increase in the NUE of these treatments, allowing growers to receive a larger percentage of marketable product for the input cost and volume of nutrients compared to standard fertigation treatments.