Exogenous Applications of Moringa Leaf Extract and Cytokinins Improve Plant Growth, Yield, and Fruit Quality of Cherry Tomato

Abstract

Growth-promoting properties of moringa (Moringa oleifera) leaves were investigated for potential use in crop production by comparing the efficacy of bimonthly foliar and root applications of a moringa leaf extract [MLE (3.3% w/v)] with the cytokinins 6-benzyladenine (6-BA) and trans-zeatin (t-Z), each at 25 mg·L−1, to increase plant growth, flowering, yield, fruit size, and fruit quality of ‘Super Sweet 100’ cherry tomato (Solanum lycopersicum). Foliar-applied t-Z and root-applied MLE increased canopy biomass (P ≤ 0.01) and root- and foliar-applied MLE increased lateral vegetative shoot number (P ≤ 0.001) and plant height (P ≤ 0.001) relative to untreated control plants. Only foliar-applied MLE increased floral shoot number compared with untreated control plants (P ≤ 0.001). Plants in all treatments, except root-applied 6-BA, produced more flowers than untreated control plants (P ≤ 0.001). Plants receiving root-applied t-Z produced the greatest number of flowers followed by plants receiving root-applied MLE. Cherry tomato plants treated with root-applied t-Z or MLE produced the greatest number of fruit per plant and significantly more than untreated control plants (P ≤ 0.001). Foliar-applied 6-BA and MLE and root-applied t-Z and MLE increased yield as grams of fruit per plant compared with the untreated control (P ≤ 0.01). Foliar- and root-applied MLE increased fruit concentrations of soluble sugars (P ≤ 0.001), protein (P ≤ 0.001), antioxidants (P ≤ 0.001), and lycopene (P ≤ 0.001) compared with fruit from untreated control plants. Foliar- and/or root-applied MLE resulted in the greatest leaf concentrations of protein (P ≤ 0.01), proline (P ≤ 0.01), arginine (P ≤ 0.01), and total antioxidants (P ≤ 0.05), which were all significantly greater than the concentrations in leaves from untreated control plants. The results of this single experiment provide evidence suggesting that MLE warrants further research as an inexpensive growth promoter for enhancing tomato plant biomass, yield, and fruit quality, especially in organic crop production, which prohibits the use of many commercial synthetic plant growth regulators.