Morphological, physiological, and biochemical responses of onion (Allium cepa L.) breeding lines to single and combined salt and drought stresses

Abstract

Abiotic stresses deteriorate plant growth resulting in devastating yield losses. Salt stress solely cause ionic toxicity and disturbed homeostasis, whereas combined salt and drought stress has more pronounced effects on plants. Here we performed a pot experiment using 32 Turkish onion breeding lines and commercial cultivars for screening against salt, drought and combined salt and drought stress treatments initiated at the bulbi cation stage under greenhouse conditions. Physiological characteristics, such as gaseous exchange traits, chlorophyll index, leaf temperature, and morphological traits including number of leaves, length and diameter of leaf were measured during stress treatment and yield response of the onions was quanti ed by measuring bulb length, bulb diameter and bulb weight after harvest.Proline and malondialdehyde accumulation were estimated for biochemical effect of stress on onion genotypes. All genotypes responded differentially to the applied single and combined stresses. Overall results revealed that the breeding lines K25, U6, U17 and commercial cultivar K58, were grouped as sensitive across all stresses, whereas the breeding lines K41, U47, U49 and commercial cultivar K52, were found to be the most stable upon stress. These resilient genotypes can be used as breeding material for future abiotic stress studies.

Water Productivity Indices of Onion (Allium cepa) under Drip Irrigation and Mulching in a Semi-Arid Tropical Region of Colombia

“…In Colombia, short-day onion varieties have demonstrated excellent adaptation in regions with warm to moderately cool thermal conditions, ranging from 800 to 2500 m.a.s.l. and temperatures between 16 • C and 27 • C. The formation of bulbs is significantly favored in cultivation areas characterized by high luminosity, high daytime temperatures (25-27 • C), cool nighttime temperatures (16)(17)(18)(19) • C), and relatively low humidity during both day and night (60-70%) [12]. Commonly cultivated onion varieties in Colombia include Yellow Granex, Superex F1, Nirvana F1, Granex Carnaval, Yellow Granex Eden, Texas Early Yellow Gran 502, Red Creole, Colina F1, Híbrido Rojo F1, Rosada Milenio F1, Dulcinea F1, Sierra F1, Roja Eureka F1, and Francisca F1 [13].…”

“…Bulb onion is a shallow-rooted crop; its root penetration is around 0.18 m, so it cannot uptake moisture from deep soils [17]. The root systems of onion plants make them susceptible to fluctuations in soil moisture, leading to decreased yield.…”

Onion (Allium cepa L.) and Drought: Current Situation and Perspectives

“…However, a decrease in soil moisture leads to a reduction in onion plant height in the field [ 18 ]. Onion field and greenhouse experiments have shown that 20–45 days of drought negatively affects morphological parameters such as leaf number, length, width, and area, with a high rate of leaf senescence [ 1 , 83 , 84 ]. This proves that leaf senescence is a typical symptom during drought, which increases with stress severity in onions [ 85 ].…”

“…Photosynthetic pigments such as chlorophyll a, chlorophyll b, and carotenoids decreased in leaves when drought stress of 10–20 days was imposed on onion seedlings transplanted in pots and greenhouses [ 83 , 92 , 93 ]. This reduction in assimilative pigment levels during the growth phase causes a decrease in the photosynthetic activity, resulting in low organic matter synthesis in onion plants [ 84 ]. Several other works have demonstrated the effect of drought on chlorophyll in onion plants [ 91 , 94 ].…”

Developing future heat-resilient vegetable crops

“…Generally, drought coincides with higher air temperature that enhances evapotranspiration resulting in closure of stomata, reduction in photosynthetic rate and damage to photosynthetic pigments (Giordano et al 2021). Currently, several studies have been reported to reveal the effect of combined stresses to adapt vegetable crops to cope with future climatic changes to ensure food security (Demirel et al 2020;Mushtaq et al 2022;Gökçe et al 2022).…”