Silicon via fertigation with and without potassium application, modulates plant water content, gas exchange, and growth of common beans cultivated in the field under different soil water levels

Abstract

Frequent droughts have led to an expansion of irrigated common bean cultivation areas. An effective strategy to enhance water use efficiency and optimize crop growth is the application of silicon (Si) and potassium (K). However, the interaction between Si dosage, water regimes, and plant potassium status, as well as the underlying physiological mechanisms, remains unknown. This study aimed to assess the effects of Si doses applied via fertigation under various water regimes, in the presence and absence of potassium fertilization, on gas exchange, water use efficiency, and growth of bean crops in field conditions. Two experiments were conducted, one with and one without K supply, with the same treatments evaluated in both experiments. The treatments comprised a 3x4 factorial design, encompassing three water regimes: 80% (no deficit), 60% (moderate water deficit), and 40% (severe water deficit) of soil water retention capacity, and four doses of Si supplied via fertigation: 0, 4, 8, and 12 kg ha− 1. The optimal doses of Si for fertigation application, leading to increased Si absorption in plants, varied with decreasing soil water content. The respective values were 6.6, 7.0, and 7.1 kg ha− 1 for the water regimes without deficit, with moderate water deficit, and with severe water deficit. Fertigation application of Si improved plant conditions, particularly under severe water deficit, regardless of potassium status. This improvement was evident in relative water content, leaf water potential, and membrane resistance, directly impacting pigment content and gas exchange rates. The physiological effects resulted in enhanced photosynthesis in water-deficient plants, mitigating dry mass production losses. This research demonstrates, for the first time in this species, the potential use of Si in irrigated crops to enhance irrigation efficiency in areas limited by low precipitation and water scarcity. Given the global implications of climate change and the increased frequency of droughts, these findings are significant.