Enhancing onion growth and yield quality via soil amendments and foliar nutrition under deficit irrigation

Abstract

EVELOPING a modern approach to sustain strategic crop productivity under conditions of water scarcity is a matter that occupies the thoughts of all researchers in the field of agricultural scientific research. So, a research trial was performed during the growing season of 2022/ 2023 for improving the onion growth performance and its quantitative and qualitative yield under deficit irrigation via some soil amendments and some beneficial element spraying. Three irrigation regimes [I 1 : Four irrigations, I 2 : Three irrigations and I 3 : Two irrigations were evaluated as main plots. The soil amendments [T 1 : Without soil amendments), T 2 : Biochar, T 3 : Zeolite, T 4 : Compost (plant residues), at rate of 10 Mg ha -1 for each soil amendment] were evaluated as sub main plots. Also, the foliar application of nutrient elements [F 1 : Without foliar application, F 2 : Boron, F 3 : Copper, F 4 : Selenium, at rate of 10 mg L -1 for each element) was assessed as sub-main plots. Parameters expressing the growth performance (e.g., foliage dry weight, chlorophyll, proline and catalase enzyme) at the period of 75 days from transplanting were determined. Also, traits expressing quantitative yield (e.g., total and marketable bulb yield) and qualitative yield (e.g., carbohydrate, protein, vitamin C, total dissolved solids and pyruvic acid) were estimated. The findings indicate that the traditional irrigation approach (I 1 ) caused the best performance in terms of both quantitative and qualitative yield. Following this, the water deficit treatments (I 2 and I 3 ) resulted in lower performance, as the I 3 treatment led to the lowest performance. When considering soil amendments, compost proved to be the most effective, followed by zeolite, then biochar, while, the control treatment ( without soil amendments) was the least effective. Regarding the beneficial elements, the order of effectiveness from most to least was Se > Cu > B > F 1 (control). Generally, the most favorable outcomes were observed when combining compost (T 4 ) with selenium foliar application (F 4 ), within the framework of the traditional irrigation treatment (I 1 ). Notably, the growth performance, as well as the quantitative and qualitative yield, were better when employing the combined approach of compost (T 4 ) and selenium foliar application (F 4 ) under the water deficit treatment (I 2 ) compared to plants grown traditionally without any of the studied substances (I 1 x T 1 x F 1 ). In conclusion, this research underscores the potential of soil amendments, and nutrient application strategies to enhance onion growth and yield under water scarcity. By continuously refining these approaches and embracing a holistic perspective, the agricultural community can move closer to ensuring food security and sustainability in challenging environmental conditions.