Far-red light interacts with wind-induced stress in cucumber seedlings

Abstract

Strong wind inhibits plant growth by creating mechanical stress and increasing water loss by increased transpiration. In the present study, we focused on far-red (FR) light as a factor that interacts with the effects of strong wind. We investigated the effect of wind speed (0.5 or 6.5 m s–1) on growth, photosynthate allocation, and stomatal conductance (gs) of cucumber (Cucumis sativus) seedlings under illumination with FR light (FR+) or without it (FR–). Interactions between wind speed and FR light influenced plant growth; strong wind decreased plant growth under FR+, but not under FR–. The growth decrease caused by strong wind resulted from decreases in the net assimilation rate (NAR) and leaf area ratio (LAR). The decreased LAR caused by strong wind was probably caused by decreased photosynthate allocation to the leaves as a result of the increased photosynthate allocation to the stem to resist the wind-created mechanical stress. The strong wind did not influence the photosynthate allocation under FR–, probably because the mechanical stress caused by the strong wind was smaller when stem elongation was decreased by FR–. The decrease in gs due to strong wind was smaller under FR– than under FR+. This may be a result of increased tolerance to water stress, which is associated with the increased proportion of active phytochrome under FR–, and may explain why the decrease in NAR due to the strong wind was smaller under FR–.