| Total soybean root length is positively correlated to grain yield, and the growth of root is regulated by various hormones. Gibberellic acid is a kind of important endogenous hormone,while the sensitivities of shoots and roots are different to GA. To explore the regulatory effect of different concentration of GA on root formation in period of root formation, indeterminate podding habits variety "Dongnong 42" and the sub-indeterminate podding habits variety "Suinong 28" were used as the experimental material. To build a gradient of GAs level in the seed, we respectively used GA3, water and S3307(inhibitor of GA3) for seed soaking. The regulatory function of GA on root formation of soybean was systematically studied from lateral root morphology, microstructure, aspects and key enzymes respectively, meanwhile supplementary field experiment was conducted to study the influence on yield and quality of soybean. The main results were:1. The contents of 3 endogenous phytohormones including indole acetic acid(IAA),gibberellic acid(GA3) and abscisic acid(ABA) in the root were investigated by high performance liquid chromatogrpahy tandem mass spectrometry. The results showed that GA3 contents in the root mature zone of GA3 treatment were significantly higher than G0(water treatment), while GA3 contents of S3307 treatment were significantly lower than G0. Therefore the GAs concentration gradient we builded using S3307 and GA3 treatment respectively for low GAs level and high GAs level was reasonable which laid the foundation of subsequent experiment.GA3 contents in roots decreased with the growth of plants under the GA3 treatment, while the GA3 contents in roots increased with the growth of plants under the S3307 treatment.2. Total root length, total surface area, total volume, average diameter were measured by using the image analysis systems of WinRhizo Pro 5.0. The results showed that total root length,total surface area, total volume, average diameter of high GAs level treatment of both the two varieties were all lower than G0, while these indexes of low GAs level treatment were all higher than G0. At 144 h, total root length, total surface area, total volume, average diameter of G200 treatment of Suinong 28 significantly fell by 19.5%, 24.9% and 29.8% respectively than G0,meanwhile these indexes of S1 treatment significantly increase by 18.2%, 14.1%, 10.7%respectively than G0.3. Lateral root slices of microstructure were made by paraffin method, and lateral root diameter, pericycle diameter, the thickness of the cortex, the cortex cell size were measured. The lateral root diameter, pericycle diameter, the thickness of the cortex, the cortex cell size of G200 treatment of Suinong 28 significantly fell by 32.9%, 34.8%, 32.5% and 20.3% respectively than G0, while these indexes of G800 treatment of Dongnong 42 significantly fell by 34.7%, 32.2%,36.0% and 23.2% than G0. Therefore the high GAs level treatment of both the two varieties could suppress the lateral root from pericycle diameter, thickness of the cortex, the cortex cell size. The lateral root diameter, pericycle diameter, the thickness of the cortex, the cortex cell size of S4 treatment of Suinong 28 fell by 2.97%, 2.17%, 3.25% and 9.1% respectively than G0,while these indexes of S4 treatment of Dongnong 42 fell by 4.2%、4.6%、3.7%、1.8% than G0.According to the results of significance analysis, the decline of lateral root diameter of Suinong28 was due to the thickness of the cortex and cortex cells, while lateral root diameter of Dongnong 42 decreased was caused by the decrease of pericycle diameter. By comparison with low GAs level treatment, the lateral root diameter, pericycle diameter, the thickness of the cortex,the cortex cell size and cortical cell layers of high level GAs treatment were significantly lower.4. Glycosidic enzyme activity and superoxide gasification enzyme activity(SOD), peroxidase activity(POD), catalase activity(CAT) in maturation zone of primary root in period of root formation were measured by colorimetric method. Glc activity was maximum at 96 h, the activity of G200 treatment of Suinong 28 fell by 3.4% than G0, while the activity of S4 treatment increased by 10.3% than G0. Glc activity of G800 treatment of Dongnong 42 fell by 9.7% than G0, while the activity of S4 treatment increased by 31.6% than G0. High GAs level treatment could suppress Glc activity in period of root formation, meanwhile low GAs level treatment could promote Glc activity. SOD activity changed little, while POD and CAT activity increased gradually in period of root formation. Compared with G0, SOD, POD and CAT activities of different GAs treatment were all increased. The enzyme activity of G200 and S1 of Dongnong42 significantly increased, while the enzyme activity of G100 and S1 of Suinong 28 significantly increased too. High GAs level treatment and low GAs level treatment could promote SOD, POD and CAT activities in period of root formation.5. Field extension test: plant height, chlorophyll content and photosynthetic indicators were measured during seedling stage, peak flowering, podding period and seed-filling period, whilethe yield components were measured during harvest time. In seedling stage, high GAs level treatment promoted chlorophyll content, while low GAs level treatment could suppress chlorophyll content. With the development of growth period, the chlorophyll content of all treatments did not show significant difference. Plant height of high GAs level treatment had no significant difference with G0, while plant height of low GAs level treatment was higher than G0.At the pod-setting stage and seed-filling period, the Pn, Cond, Ci, Tr of high GAs level treatment and low GAs level treatment were all significantly higher than G0. The treatments of GAs had no significant effect on yield. |
PDF Full Text Request