Effect of elevated atmospheric co2on nitrogen distribution and n utilization efficiency in winter rape (Brassica napus L.)

We characterized the responses of plant dry biomass,nitrogen (n) distribution and n-utilization efficiency (nute) to changes in co2 concentration through exposure and culture of winter rape under normal-(380 μmol·mol-1) and elevated-co2 (760 μmol·mol-1) conditions. brassica napus (xiangyou 15) was used as an agriculturally important model plant. plants were cultivated in a greenhouse with sand culture under normal- (15 mmol·l-1) and limited-n (5 mmol·l-1) conditions. nute increased with elevated co2 regardless of whether n was limited. nute was higher under n limitation than under normal n conditions for both normal- and elevated-co2 conditions.15n labeling was used to assess the distribution of n from vegetative- to reproductive-organs.ndistribution within the plant and during different developmental stages was affected by co2 concentration and the level of n application. a higher proportion of n was found in siliques at the harvest stage for n-limited plants compared to normal-n plants. the proportion of n absorbed into siliques after the stem elongation stage under elevated-co2 conditions was significantly higher than under normal co2. the proportion of n transport,as well as the total amount of n,absorbed at the stem elongation stage from vegetative organs into siliques under elevated co2 was significantly lower than under normal-co2 conditions. however,the proportion of n absorbed at the stem elongation stage and thus lost from the silique under elevated co2 was significantly higher than under normal co2. in conclusion,limited n or elevated co2 generally benefitted plant nute. in addition,after the stem elongation stage,elevated co2 promoted the redistribution of n from plant vegetative tissues to reproductive organs; however,elevated co2 during or before stem elongation had the opposite effect. © 2017,pakistan botanical society. all rights reserved.