The effect of alginate-zeolite (3:1) Fe composite on physiological characters, stomatal density and yield of shallots (Allium cepa L. 'Bima Brebes')

Abstract

The inefficient absorption of minerals by plants can be avoided by using slow-released fertilizers. This research aims to test the efficiency of Fe-composite as a slow-released fertilizer in supporting shallots (Allium cepa L. ‘Bima Brebes’) growth and yield at the early stage of the reproductive phase. This research was conducted with shallots plant treated with the two groups including a control group and treatment group. The control group consists of control 1 (without NPK), control 2 (standard NPK), control 3 (50 ppm FeCl3 + standard NPK), while the treatment group consists of varied alginate: zeolite (3:1) Fe composite in the concentration of 50 ppm, 100 ppm, 150 ppm, 200 ppm and 400 ppm. The plant height, number of leaves and shoot fresh and dry weight were observed higher at the concentration of 150 ppm Fe-composite. Plants treated with concentrations exceeding 150 ppm tend to experience decreased growth, photosynthetic rate and low bulb yields. The analysis of starch content and Fe content in the bulbs shows that the plant treated with 150 ppm Fe-composite tends to have a higher content of both starch and Fe but is not significantly different from the treatment of 100 ppm Fe-composite. In this study, the use of Fe-composites affects the growth and yield of shallot with the optimum concentration that supports the growth and the largest tuber size in shallot is 150 ppm alginate: zeolite (3:1) Fe composite.