Photosynthetic characteristics of wheat cultivars with blue or purple grain

Changes in photosynthetic pigment content, net photosynthetic rate, stomatal conductance, transpiration rate, intercellular CO2 concentration and stomatal limitation of blue- or purplegrained wheat cultivars were compared with whitegrained wheat cultivars “Mianyang 26” and “Chuanmai 107” to determine photosynthetic characteristics of blue- or purplegrained wheat cultivars. The results show that: (1) The content of chlorophyll a, chlorophyll b and total chlorophyll of all three kinds of wheat cultivars decrease along development stages: booting, heading, flowering, filling and mature. Chlorophyll a, chlorophyll b and total chlorophyll contents of blue-grained wheat are lowest at the five stages; those of chlorophyll a and total chlorophyll of whitegrained wheat are highest at each stage, except for booting stage; and chlorophyll b content is also h+J56ighest at mature stage. Carotenoid content dynamics for purple and blue-grained wheat cultivars differ from that for white-grained wheat. Carotenoid content decreases along developmental stages in white-grained wheat, but decreases before flowering and then increases thereafter in blue- and purple-grained wheat. At filling and mature stages, carotenoid content is highest in blue-grained wheat, and lowest in white-grained wheat. (2) Net photosynthetic rate of all wheat materials increases at first and then decreases along the five developmental stages, with the highest net photosynthetic rate at flowering stage. Net photosynthetic rate of white-grained wheat is highest among the three kinds of wheat at each developmental stage, except for filling stage, and blue-grained wheat is lowest after flowering. (3) Stomatal conductance and transpiration rate of all the materials appear to have a unipeak curve, peaking at filling stage. (4) Stomatal limitation in white-grained wheat cultivars is lower than in purple- and blue-grained wheat cultivars from booting to flowering stage, but increases thereafter. It demonstrates that photosynthetic ability of blue- and purple-grained wheat cultivars is lower than that of whitegrained wheat cultivars.