Abstract: Selection and application of low nitrogen tolerant wheat cultivars (Triticum aestivum L.) is a possible option for reducing nitrogen input, increasing grain yield and improving land productivity. Seven representative wheat cultivars, with different yield levels, were used as tested material. Field experiment and laboratory hydroponics experiment were conducted during 2016- 2017 wheat growing season with the following objectives as: (i) to assess the yield response of different wheat cultivars to low nitrogen stress; (ii) to determine the photosynthetic mechanisms and the feasible photosynthetic parameters for selection of low nitrogen tolerant wheat cultivars. The field experiment consisted of 7 treatments (wheat cultivar), i.e., ‘Luohan 6’, ‘Shimai 15’, ‘Xuke 316’, ‘Xianmai 10’, ‘Liangxing 99’, ‘Xinong 979’, and ‘Bainong 418’. The laboratory hydroponics experiment consisted of 15 treatments, i.e., the combinations of 3 representative wheat cultivars (‘Luohan 6’, ‘Xianmai 10’, and ‘Liangxing 99’) and 5 nitrogen supply levels (0, 5, 10, 20, and 40 mmol/L). Field experiment and laboratory hydroponics experiment both followed a randomized block design. The results showed that the low nitrogen tolerant wheat cultivar ‘Liangxing 99’ increased wheat yield by 11.6% when compared with low nitrogen sensitive cultivar ‘Luohan 6’. Under low nitrogen stress in both field and laboratory experiments, low nitrogen tolerant wheat cultivars had relatively greater net photosynthetic rate, transpiration rate, stomatal conductance, and carboxylation efficiency. Low nitrogen tolerant wheat cultivars can be preliminarily selected by using hydroponics experiments with the above-mentioned photosynthetic parameters as evaluation indicators. Overall, selection and application of low nitrogen tolerant wheat cultivars is of great significance to improving wheat productivity under low nitrogen stress. Some photosynthetic traits can be used to select low nitrogen tolerant wheat cultivars.

Key words: wheat, photosynthetic response, low nitrogen stress, grain yield, hydroponics