Under hydroponic conditions with diverse N deficiency levels, the

Under hydroponic conditions with diverse N deficiency levels, the root surface area and belowground biomass of switchgrass were reduced by deficient N (Table 2), so that WUE decreased as N decreased (Table 3). The rate of transpiration

is directly related to the degree of stomatal opening, and to the evaporative demand of the atmosphere surrounding the leaf. Deficiency of N can influence stomatal opening, and thus transpiration rate. There are contradictory conclusions in the literature about the influence of N deficiency on stomatal conductance. Lower rates of stomatal conductance in low-N-grown plants have been reported [28] and [29], GKT137831 solubility dmso but the opposite or no effect of N application is also reported [26] and [30]. Possible reasons could lie in the choice of tested materials and experimental conditions. In the present study, under N deficiency stress, the stomatal www.selleckchem.com/epigenetic-reader-domain.html conductance of switchgrass decreased considerably (Table 3). Given that the amount of transpiration by a plant

depends on the number and size of leaves, leaf areas, and plant roots, seedlings grown with nutrient solution lacking N showed a drop in transpiration rate (Table 3). Full-strength Hoagland’s nutrient solution treatment supported the highest value of transpiration because of the increased photosynthesis and stomata conduction. There is a linear correlation between photosynthesis and transpiration [31] and [32]. Thus, for hydroponically cultivated switchgrass, deficient N supply affected the chlorophyll content and stomatal opening

and thereby the leaf area and photosynthetic characteristics. This effect reduced the plant’s ability to manufacture carbohydrates by photosynthesis and consequently reduced its biomass. The results agree with TCL the findings by Stroup et al. and Kering et al. [24] and [33]. All the traits showed obvious differences among the applied N deficiency stresses (Table 2 and Table 3), suggesting that switchgrass responds strongly to N. However, the tiller number showed no significant difference across cultivars and ecotypes and no cultivar-by-treatment and ecotype-by-treatment interactions (Table S1). One possible explanation would be that the six chosen switchgrass cultivars simply show no difference in tiller number. This could also explain why R:S showed no difference across ecotypes but showed highly significant differences across treatments. There is no current index for evaluating the tolerance of switchgrass to mineral nutrient deficiency conditions. According to previous indoor and field study experiments, combined with the physiological characteristics of switchgrass, total biomass, height, tiller number, leaf area, root surface area, net photosynthesis and chlorophyll content were chosen as evaluation indices for effectively measuring its performance.

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