UV-B增强下施硅对水稻抽穗期生理特性日变化的影响

通过盆栽试验,研究了UV-B增强下施硅对水稻抽穗期光合和蒸腾生理相关参数日变化的影响.光辐射设对照(自然光,A)和UV-B辐射增强(比自然光增加20%,E)2个水平;硅肥设4个水平,即Si₀(不施硅,0 kg SiO₂·hm^-2)、Si₁(硅酸钠,100 kg SiO₂·hm^-2)、Si₂(硅酸钠,200 kg SiO₂·hm^-2)和Si₃(钢渣硅肥,200 kg SiO₂·hm^-2).结果表明: 不施硅条件下(Si₀),UV-B增强处理的净光合速率(P_n)、胞间二氧化碳浓度(C_i)、蒸腾速率(T_r)、气孔导度(g_s)和水分利用效率(WUE)的日均值比对照(A)分别下降了11.3%、5.5%、10.4%、20.3%和6.3%,施硅条件下(Si₁、Si₂和Si₃)上述参数则分别下降了3.8%～5.5%、0.7%～4.8%、4.0%～8.7%、
7.4%～20.2%和0.7%～5.9%,说明UV-B增强降低了水稻P_n、C_i、T_r、g_s和WUE,而施硅能缓解UV-B增强引起的抑制效应.UV-B增强下施硅处理(Si₁、Si₂和Si₃)的P_n、C_i、g_s和WUE的日均值比不施硅对照(E+Si₀)分别提高了16.9%～28.0%、3.5%～14.3%、16.8%～38.7%、29.0%～51.2%,T_r降低了1.9%～10.8%,说明施硅通过显著提高水稻P_n、C_i、g_s和WUE,降低T_r,以缓解UV-B增强引起的抑制效应.不同施硅处理对UV-B增强的缓解效应存在明显差异,表现为Si₃ >S/a#₂>Si₁>Si₀.表明在水稻生产中,施用钢渣硅肥不仅能实现废弃物再利用,而且可有效缓解UV-B增强对水稻光合和蒸腾生理的抑制作用.

Effects of silicon supply on diurnal variations of physiological properties at rice heading stage under elevated UV-B radiation.

A pot experiment was conducted to investigate the effects of silicon (Si) supply on diurnal variations of photosynthesis and transpiration related physiological parameters at rice heading stage under elevated UV-B radiation. The experiment was designed with two UV-B radiation levels, i.e. ambient UV-B (ambient, A) and elevated UV-B (elevated by 20%, E), and four Si supply levels, i.e. Si₀ (control, 0 kg SiO₂·hm^-2), Si₁ (sodium silicate, 100 kg SiO₂·hm^-2), Si₂ (sodium silicate, 200 kg SiO₂·hm^-2), Si₃ (slag fertilizer, 200 kg SiO₂·hm^-2). The results showed that, compared with ambient UV-B radiation, elevated UV-B radiation decreased the net photosynthesis rate (P_n), intercellular CO₂ concentration (C_i), transpiration rate (T_r), stomatal conductivity (g_s) and water use efficiency (WUE) by 11.3%, 5.5%, 10.4%, 20.3% and 6.3%, respectively, in the treatment without Si supply (Si₀ level), and decreased the above parameters by 3.8%-5.5%, 0.7%-4.8%, 4.0%-8.7%, 7.4%-20.2% and 0.7%-5.9% in the treatments with Si supply (Si₁, Si₂ and Si₃ levels), respectively. Namely, elevated UV-B radiation decreased the photosynthesis and transpiration related physiological parameters, but silicon supply could obviously mitigate the depressive effects of elevated UV-B radiation. Under elevated UV-B radiation, compared with control (Si₀ level), silicon supply increased P_n, C_i, g_s and WUE by 16.9%-28.0%, 3.5%-14.3%, 16.8%-38.7% and 29.0%-51.2%, respectively, but decreased T_r by 1.9%-10.8% in the treatments with Si supply (Si₁, Si₂ and Si₃ levels). That is, silicon supply could mitigate the depressive effects of elevated UV B radiation through significantly increasing P_n, C_i, g_s and WUE, but decreasing T_r. However, the difference existed in ameliorating the depressive effects of elevated UV-B radiation on diurnal variations of physiological parameters among the treatments of silicon supply, with the sequence of Si₃>Si₂>Si₁>S/a#₀. This study suggested that fertilizing slag was helpful not only in recycling industrial wastes, but also in effectively mitigating the depressive effects of elevated UV-B radiation on photosynthesis and transpiration in rice production.