Response of Hydroponically Grown Cherry and Fresh Market Tomatoes to Reduced Nutrient Concentration and Foliar Fertilizer Application under Shadenet Conditions

Reduced nutrient concentration (NC) through fertigation in an open-bag hydroponic system with additional foliar fertilizer application may reduce nutrient wastage and thus decrease the production costs. A study was conducted to determine the effect of foliar fertilizer in combination with reduced NCs on the yield and quality of hydroponically grown cherry and fresh market (FM) tomatoes in a shadenet structure. In the first experiment, FM tomato plants were grown in sawdust fertigated with nutrient solutions containing 100% (control), 75%, 50%, or 25% of the recommended NC. Marketable yield and fruit mineral content were unaffected by NC, whereas the total yield decreased with a decrease in NC. The second and third experiments were on FM and cherry tomatoes, respectively, subjected to four NCs (100%, 75%, 50%, or 25%) and two foliar fertilizer applications (no foliar and foliar application). Fresh and dry weight of FM and cherry tomato plants decreased with a decrease in NC application. Marketable yield on FM tomatoes increased with 50% to 100% NC, whereas the total yield increased with 75% and 100% NC, as compared with 25% NC. Cherry tomatoes produced lower marketable yield at 25% and 50% NC, as compared with 75% and 100% NC. Foliar fertilizer application did not have an effect on FM and cherry tomato yield, but improved the plant dry weight of cherry tomatoes. Fruit and leaf Ca content of FM tomatoes were improved by the decrease in the NC. Fruit mineral content (K, P, Ca, Mg, and Zn) of cherry tomatoes increased with an increase in NC. The improvement in yield was primarily due to nutrient uptake, especially, N, P, and K, as determined in tomato leaves. Reduced NC of 50% can maintain yield and quality of FM tomatoes, whereas application of foliar fertilizer had a limited effect. In cherry tomatoes, yield and fruit mineral content were maintained at 75% NC combined with foliar fertilizer application. The findings of this research may reduce nutrient wastage and result in a cost saving of 25% and 50% on fertilizer input costs on cherry and FM tomatoes, respectively, and reduce the risk associated with water pollution.