Effect Of Root Physiological Characteristics Of Two Winter Wheat Genotypes On Molybdenum Nutrition Efficiency

The materials used for the experiment were Mo-efficient winter wheat genotype97003and Mo-inefficient winter wheat genotype97014. Root-box culture and solution culture experiments were conducted to investigate root physiological characteristics of two winter wheat genotypes on Molybdenum nutrition efficiency. The main results as follows:1. There were differences of dry matter and grain yield between Mo-efficient and Mo-inefficient winter wheat genotypes. The dry matter of97003was higher than97014at different stages under Mo-deficient condition, which was significantly higher at Maturity stage. The accumulation rate of dry matter and harvest index in97003were higher than97014. The yields of97003in the treatment of Mo-deficient were almost same as the treatment of Mo application; however, the yields of97014in the treatment of Mo-deficient were only66.7%of yields in the treatment of Mo application.2. There were differences of molybdenum uptake, accumulation and distribution between Mo-efficient and Mo-inefficient winter wheat genotypes. The accumulation of molybdenum in shoots of genotype97003was higher than97014at jointing stage, heading and maturity on root-box experiments under the condition of molybdenum deficiency; the molybdenum accumulation of genotype97003was also higher than97014on solution culture experiments. Whether from root to shoot or from glume to grain, the transfer ability of molybdenum in genotype97003was higher than97014under the condition of Mo deficiency; Genotype97003also had higher ability to transfer Mo from root to shoots than97014in solution culture experiments. At maturity, Mo distributing in the leaves and seeds in Mo-efficient genotype97003were more than in genotype97014under the conditions of Mo deficiency.3. There were difference of available molybdenum concentration and molybdenum forms in rhizosphere and non-rhizosphere soil between Mo-efficient and Mo-inefficient winter wheat genotypes. The available molybdenum concentrations of rhizosphere soil were higher than non-rhizosphere soil at different stages in winter wheat. The available molybdenum in rhizosphere soil of97003was significantly higher than97014at the jointing stage under the condition of molybdenum deficiency, but it was lower than 97014at the seedling, heading and maturity stages; the sum of four Mo fractions such as water soluble, weak acid soluble, oxide bound and organic bound in rhizosphere soil of97003was higher than97014at the different growth stages under the conditions of Mo deficiency.4. There were remarkable differences of the roots morphology between different Mo efficiency of winter wheat genotypes. There were significantly or highly significantly positive correlations between molybdenum accumulation and root surface area, root volume, average diameter under Mo-deficient conditions respectively; it also was correlated with root length positively. Root length, root surface area, root volume and average diameter of genotypes97003were significantly higher than genotype97014under the condition of molybdenum deficiency5. There were remarkable differences of root secret between different Mo efficiency of winter wheat genotypes. tartaric acid, malic acid and acetic acid three kinds’organic acids were found in root exudates, and the malic acid was the dominant organic acids in root exudates. Organic acids of root exudates in the molybdenum application treatment were always higher than that in the molybdenum deficiency treatment and organic acid secretions of97003were slightly lower than97014under the condition of molybdenum deficiency.