Development of water treatment methods and crop management methods for suppressing crop photoinhibition

本项目的目标是开发一种能够减少作物光合作用光抑制的灌溉水处理方法和/或作物管理方法。Shirahata et al.(1997)报告说，电解还原的水具有清除活性氧的能力。基于这份报告和关于光抑制是由活性氧引起的既定知识，我们提出了一个工作假说：给作物提供电解还原水可以减少它们的光抑制。为了验证这一工作假说，我们向甘薯原生质体施加电解还原水，并通过叶绿素荧光法(Mini-PAM)测定光抑制程度，并通过发光素测定O2~-的产生速率。所获得的结果不支持工作假说。用细胞色素C法测定电解还原水清除O2~-的能力也不支持这一假说。ESR测定O^2-的结果表明，与纯水相比，电解还原水中的O2-含量更高。叶片中高含量的类胡萝卜素具有很强的抑制活性氧产生的能力。因此，我们研究了通过控制应用于作物的光质(光谱)来减少光抑制的可能性。比较了在蓝、红、白三种荧光灯下生长的小米菜叶中类胡萝卜素的含量。结果表明，与其他光照相比，红光提高了类胡萝卜素的含量。

The objective of this project was to develop an irrigation water treatment methods and/or crop management methods which could reduce photoinhibition of crop photosynthesis. Shirahata et al. (1997) reported that electrolyzed-reduced water had a power to scavenge active oxygen. Based on this report and an established knowledge that photoinhibition was caused by active oxygen, we made a working hypothesis : photoinhibition of crops could be reduced by giving them electrolyzed-reduced water. To verify this working hypothesis, we applied electrolyzed-reduced water to protoplasts from sweetpotato and determined the degree of photoinhibition by chlorophyll fluorescence (Mini-PAM) and also measured production rate of O2^- by luminescence from lucigenin. The results obtained did not support the working hypothesis. A measurement of O2^- scavenging power of electrolyzed-reduced water by Cytochrome C method did not support the hypothesis, either. Measurement of O^2- by ESR resulted in higher O2^- content in electrolyzed-reduced water compared to pure water.High cartenoid content in leaves is known to have a high ability of suppressing active oxygen production. Therefore, we investigated the possibility of reducing photoinhibition by controlling light quality (spectrum) applied to crops. We compared cartenoid contents in leaves of Komatsuna (Brassica campestris L) grown under blue, red and white fluorescence lamps. The results indicate that red light increased cartenoid content, compared to the other lights.