Characterization of nitrogen metabolism and photosynthesis in a stay-green rice cultivar

Abstract

A field experiment was carried out in the years 2008-2011 in China to assess the nitrogen metabolism enzyme activities and photosynthetic characteristics in stable-yielding stay-green rice (Oryza sativa L.) cv. Shennong196. The results showed that higher levels of nitrogen content, nitrate reductase activity, and glutamine synthetase activity occurred in leaves of cv. Shennong196 compared with cv. Toyonishiki (control). Leaf color of cv. Shennong196 was positively correlated with nitrogen levels and nitrogen metabolism enzyme activities (P < 0.05). Superoxide dismutase activity and malondialdehyde contents were 18.53 unit/g fresh weight and 3.32 nmol/g, respectively, which were lower in flag leaves of cv. Shennong196 than cv. Toyonishiki. Cv. Shennong196 had a higher level of net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, and transpiration rate in flag leaves of diurnal variation of photosynthesis at the ripening stage. The high net photosynthetic rate in cv. Shennong196 was positively correlated with the stomatal density of flag leaves (P < 0.01). Considering the yield-increasing potential and to prevent premature senescence of crop, these traits of cv. Shennong196 are useful for improved rice cultivar.

Keywords

• macronutrient
• carotenoid
• leaf senescence
• stay-green plant
• plant density
• antioxidant enzyme