Morphophysiological characteristics of garlic cultivars subjected to different levels of water deficit

Abstract

Garlic (Allium sativum L.) is a crop of great economic importance worldwide. Proper irrigation management is fundamental for the productivity and quality of the crop. In the context of climate change, research seeking cultivars with characteristics tolerant to water deficit is essential. Therefore, this study aims to verify the anatomical, physiological, and biochemical leaf modifications of garlic cultivars subjected to water deficit and their effect on bulb production. The cultivars studied were Caçador, Ito, Quitéria, Chonan, Lavinia, Gravatá, Amarante, Crespo, Gigante Roxo, BRS Hozan, Chinês PR, Mexicano, Chinês São Joaquim, Catiguá, and Chinês Folha Larga, subjected to four water conditions: 100, 75, 50, and 25% of the substrate's water retention capacity, conducted in a 4×15 factorial design (four water conditions and fifteen garlic cultivars). Garlic cultivars with water deficit tolerance characteristics were identified. Under water deficit, we observed anatomical leaf changes such as: increased stomatal density, mesophyll thickness, and palisade and spongy parenchyma thickness; cuticle thickness; a reduction in xylem vessel diameter and a greater number of vascular bundles in the mesophyll, which directly reflect on the photosynthetic rate of the cultivars and bulb production. We observed biochemical leaf adjustments such as increased sucrose content in some cultivars. It was also observed that garlic cultivars have a great capacity for photosynthetic recovery after a 10-day period under total water deficit. The set of evaluated characteristics demonstrates the strong correlation between anatomy, physiology, and biochemical activity and how these characteristics influence plant production, providing important information for crop breeding programs and garlic producers. We also emphasize the importance of research to understand the characteristics that lead to garlic plants' tolerance to water deficit, and the importance of controlled irrigation to increase the efficient use of water in agriculture.