Rapid Suppression of Growth by Blue Light

Abstract

The mechanism of the rapid inhibition of hypocotyl elongation by blue lght was investigated in cucumber (Cucumis sativus L.) and sunflower (Helnthus annus L.) where dV/dt is the relative rate of volume increase, L is the cell hydraulic conductance, 0 is the cell wall extensibility, a is the solute reflection coefficient, Air is the difference in osmotic potential between the inside and the outside of the cell, and Y is the yield threshold for wall expansion. In principle, light may act on any of these parameters to decrease the growth rate.As described at length in the preceding report (4), measurements of turgor pressure and half-time for changes in growth rate provide

Nets for Peach Protected Cultivation

“…For the YELLOW net and the GREY net the vegetative growth was mainly connected to their radiometric characteristics, thus reducing summer stress conditions. The vegetative growth was less manifest inside the greenhouses covered with the NEUTRAL net and the BLUE net; this was probably due both to their B/FR ratios, similar (3.69 for the NEUTRAL net) or higher (5.42 for the BLUE net) than the outdoor ratio (3.75), and to the presence of blue radiation (B, 400-500 nm) in the growing environment, which has a depressive effect on tree growth [Cosgrove 1981]. Concerning the qualitative characteristics of the fruits, the PEARL net and the NEU-TRAL net, as shown also in Shahak [2004], influenced positively the weight of the fruits.…”

Ethylene Is Not Involved in the Blue Light-Induced Growth Inhibition of Red Light-Grown Peas

“…Shinkle and Jones (10) found that when cucumbers were grown in red light, blue light inhibited the growth of sections by approximately 50%, a much greater degree of inhibition than was seen in sections excised from dark-grown plants (2). Previous experiments with etiolated pea seedlings have demonstrated that exposure to red light results in the suppression of endogenous ethylene production (5).…”

“…Blue light irradiation can inhibit stem elongation in dicotyledonous seedlings that have been grown in the dark or in red light by as much as 80% (1,2,6,8 ethylene induced a growth inhibition of approximately 60%. The inhibition began about 6 min after ethylene application in 4-d-old etiolated pea (Pisum sativum) seedlings.…”

“…Blue light irradiation can inhibit stem elongation in dicotyledonous seedlings that have been grown in the dark or in red light by as much as 80% (1,2,6,8). The elongation rate of excised stem segments, however, is much less sensitive to blue light.…”

“…Also, the inhibition response of red light-grown seedlings is the same whether ethylene is present from the onset of continuous blue-light treatment or not. Finally the spatial distribution of inhibition following blue light was different from that following ethylene treatment.Blue light irradiation can inhibit stem elongation in dicotyledonous seedlings that have been grown in the dark or in red light by as much as 80% (1,2,6,8 ethylene induced a growth inhibition of approximately 60%. The inhibition began about 6 min after ethylene application in 4-d-old etiolated pea (Pisum sativum) seedlings.…”