Zinc, Manganese, and Iron Fertilization in `Spineless Beauty' Zucchini (Cucurbita sp.)

Abstract

Zucchini (Cucurbita sp.) fruit yield response to zinc (Zn), manganese (Mn), and iron (Fe) foliar fertilization was determined in field trials conducted in a loamy clay soil in Nigua, San Cristobal, Dominican Republic. The soil had Zn, Mn, and Fe contents of 1.2, 8, and 2 parts per million (ppm), respectively. `Spineless Beauty' zucchini was direct-seeded at a distance of 1 m between rows and 0.5 m within rows. Except for Zn, Mn, and Fe fertilization, the crop was grown according to recommended practices. Experimental units contained five plants. A randomized complete-block design with a factorial arrangement (3 × 3 × 3) with four replications was utilized. Micronutrient rates were 0, 1, and 3 kg·ha–1 for Zn; 0, 3, and 6 kg·ha–1 for Mn; and 0, 3, and 6 kg·ha–1 for Fe. Total rates were divided in two 50% rate applications, sprayed in aqueous solution to the crop leaves 15 and 30 days after emergence. Fruit harvest began 40 days after crop emergence and was performed every other day during 20 days. Resulting data was subjected to analysis of variance. There were significant Zn, Mn, and Fe interactions, and thus micronutrient combinations were considered as individual treatments. Treatment means were separated with the lsd 5% test. Zucchini plants treated with a combination of 3 kg Zn/ha, 3 kg Mn/ha, and 3 kg Fe/ha produced fruit yields 31.5% higher than control plants. Combinations including higher Mn and Fe rates failed to further increase zucchini yields.