Photosynthetic pigments and gas exchange in red and green cabbage under no-tillage and conventional systems

ABSTRACT The aim of the present study was to verify changes in the levels of photosynthetic pigments as well as gas exchange in the Fuyutoyo and Red Cabbage cultivars, grown under no-tillage (NT) and conventional (CT) systems. A randomised block design with four replications was used, in a 2 x 2 factorial scheme, where the Fuyutoyo and Red Cabbage cultivars were evaluated under two tillage systems. The levels of chlorophyll a, chlorophyll b, total chlorophyll and anthocyanins in the leaves were evaluated in triplicate. Localised gas exchange was measured at different times of the day, together with different photosynthetic photon flux density curves (PPFD). The Fuyutoyo cultivar showed a higher mean value for chlorophyll a (34.58%), chlorophyll b (35.09%) and total chlorophyll (34.76%), however, no difference was seen between cultivars for the levels of anthocyanin. Greater mean values for chlorophyll a (76.07%), chlorophyll b (77.87%), total chlorophyll (76.74%) and anthocyanin (72.24%) were found under CT compared to the cultivars grown under NT. The relative chlorophyll content of the Red Cabbage plants was influenced by adoption of the no-till system, showing a higher value for the SPAD index. The Fuyutoyo cabbage cultivar showed greater photosynthetic capacity during the day, promoting greater instantaneous carboxylation efficiency. All the cultivars and tillage systems gave a linear reduction in water use efficiency during this period. Under the conventional system, despite presenting higher rates of stomatal conductance, the Red Cabbage cultivar achieved lower values for net photosynthesis when submitted to light-curve analysis.

摘要
本研究旨在探究免耕（no-tillage, NT）与传统耕作（conventional, CT）体系下种植的‘Fuyutoyo’与红甘蓝（Red Cabbage）两个品种的光合色素水平及气体交换参数变化。本研究采用四重复随机区组设计，设置2×2因子试验方案，在两种耕作体系下对两个供试品种进行测定。对叶片中的叶绿素a、叶绿素b、总叶绿素及花青素含量进行三次重复测定。于当日不同时段测定原位气体交换参数，并构建不同光合光子通量密度（photosynthetic photon flux density, PPFD）响应曲线。
结果表明，‘Fuyutoyo’品种的叶绿素a（34.58%）、叶绿素b（35.09%）及总叶绿素（34.76%）平均含量均显著更高，但两个品种的花青素含量无显著差异。与免耕体系种植的供试品种相比，传统耕作体系下的叶绿素a（76.07%）、叶绿素b（77.87%）、总叶绿素（76.74%）及花青素（72.24%）平均含量均显著更高。红甘蓝植株的相对叶绿素含量受免耕体系影响显著，其SPAD指数更高。‘Fuyutoyo’甘蓝品种日间光合能力更强，瞬时羧化效率更高。所有供试品种及耕作体系下，该时段内的水分利用效率均呈线性下降趋势。传统耕作体系下，尽管红甘蓝品种的气孔导度更高，但经光响应曲线分析后，其净光合速率却更低。