Genotypic differences in response of wheat lateral root growth to nitrate supply

Nutrient solution culture experiment was conducted to study effects of nitrate supply on lateral root development and nitrogen uptake of wheat. Four wheat cultivars, Shimai 15(SM15), Hengguan 35(HG35), H10 and L14 were selected as the tested crops. The results showed that biomass and nitrogen content in shoots, and lateral root development were not significantly affected under the 0-25.0 mmol/L nitrate treatments for 13 days. After 22 days of nitrate applications, the biomass and the nitrogen content in shoots increased significantly, and the increased rates of SM 15, H10 and HG 35 were higher than those of L14. With nitrate treatments at the concentration range of 0.25-20.0 mmol/L, lateral root elongation and lateral root numbers of four genotypes of wheat were not significantly affected. However, when supplied with low nitrate(0.05 mmol/L), there were notable increases in the average lengths of lateral roots of the four genotypes. Without nitrate supply or under 0.05 mmol/L of nitrate supply, lateral root length and total root length of SM 15 increased and lateral root density did not change, total length of lateral roots of H10 increased and lateral root density decreased, lateral root density of HG 35 decreased, while there were no significant changes in the total length of lateral roots and lateral root density of L14. These results suggest lateral root growths of wheat with different genotypes are different under nitrate supply.