Physiological responses and early hormonal signals associated with growth-defense trade-offs in tomato seedlings under wind-sand stress.

Abstract

<h4>Introduction</h4>Tomato is one of the most widely cultivated vegetable crops worldwide, with China as the leading producer. Xinjiang is a major tomato-producing region; however, it is frequently exposed to persistent wind and sand conditions that severely threaten seedling establishment in early spring.<h4>Method</h4>This study investigated the effects of combined Wind-sand stress on tomato seedling growth using controlled wind-tunnel experiments. Seedlings were subjected to varying intensities of wind alone (3, 5, 7, 9, 11, and 13 m/s) and sand-laden wind (5, 7, 9, 11, and 13 m/s). Changes in physiological parameters, morphology, and endogenous hormone levels (IAA, GA, Zeatin, ABA, JA, and SA) were analyzed to assess stress responses and the growth-defense balance.<h4>Result</h4>The results showed that (1) Both wind alone and sand-laden wind inhibited photosynthesis, with sand-laden wind exerting a more pronounced effect. At 13 m/s, the net photosynthetic rate (Pn) decreased by 71% under wind alone and by 98% under sand-laden conditions compared with the control. (2) Sand-laden wind caused more severe membrane damage, accompanied by higher antioxidant enzyme activities and greater accumulation of osmolytes. (3) High-intensity wind-sand stress resulted in mechanical injury, leading to systemic physiological imbalance and loss of cellular homeostasis. For example, exposure to sand-laden wind at 11 m/s damaged 89% of leaves and stomata, caused complete cuticle exfoliation, and induced abnormal physiological responses, including increased intercellular CO₂ concentration and reduced enzymatic activity. (4) Sand-laden wind significantly increased stress-related hormones, with jasmonic acid, abscisic acid, and salicylic acid rising by 6,126.3%, 205%, and 302.6%, respectively, while significantly suppressing the synthesis of growth-promoting hormones such as auxin, gibberellins, and zeatin. These pronounced hormonal changes indicate that wind-sand stress triggers a defense-oriented physiological reprogramming at the expense of growth, providing strong hormonal evidence for a growth-defense trade-off in tomato seedlings.<h4>Meaning</h4>This study elucidates the key physiological and hormonal Responses associated with combined wind-sand stress and provide a theoretical basis for stress-resilient cultivation of processing tomatoes and for the development of field-level wind damage mitigation strategies in wind-sand-prone regions.