| Maize is characterized by high fertilizer consumption, high photosynthetic efficiency, high stalk, heterosis. It’s net photosynthetic efficiency is two times of rice and wheat, the potential of high yield is huge. As the study about strobilurin fungicides gradually thorough, more and more studies proved that the strobilurin fungicide have a good regulation effect on the growth of crops; Now, the plant health effects of pyraclostrobin on maize have registered in China, but physilogical characteristics about pyraclostrobin on maize growth regulation have not reported. The study obtained the appropriate dose of pyraclostrobin on maize seed, and studied the change of physiological and biochemical indicators of pyraclostrobin on the corn seed germination and seedling growth, studied the effect of photosynthetic characteristics, photosynthetic enzyme, protective enzyme activities and some resistance matters’ content of pyraclostrobin on the maize seedling under the plot experiment in greenhouse; Studied the effects of pyraclostrobin on soil microbial respiration and soil enzyme activity, and the effect of pyraclostrobin on soil microbial respiration were evaluated by the hazard coefficient method.1、Through the sand bioassay experiment in light incubator, the Effects of pyraclostrobin seed dressing on the seed activity and the seedling growth of maize were studied. Comparing with the contrast, 2.5:10 000 ratio seed coating agent made the corn seed germination potential, germination rate, germination index and vigor index increased by 4.71, 17.4, 17.4 and 4.71% respectively, corn seedling plant height, taproot length, root number, fresh weight per plant, root-shoot ratio were increased by 0.12 cm, 0.12 cm, 0.71, 0.15 grams, 1.38, pyraclostrobin seed dressing can increase the maize seedling’s chlorophyll content, the root activity, the soluble sugar content.2、Through the sand bioassay experiment in light incubator, studied the change of physiological and biochemical indicators of pyraclostrobin on the corn seed germination and seedling growth. The result showed that as the seed germination and growth,comparing with the contrast, pyraclostrobin treatment could slow down the decomposition velocity of grain starch and other nutrients, increase the weight per plant of maize seedling, promote the plant height, root length markedly; As the seed germination and growth,α-amylase activity and reducing sugar content gradually increasing, comparing with the contrast, low dosage treatment of pyraclostrobin increased the α-amylase activity, high concentration treatment(20:10000)inhibited theα-amylase activity obviously; Reducing sugar content of high dose treatment(5:10000、10:10000、20:10000) below control treatment and low dosage treatment obviously. In the process of seed germination and growth, the relative conductivity of seed increased gradually, pyraclostrobin treatment could decrease the relative conductivity. Soluble protein content could reach the top at the third day, and the content of high dose treatment(5:10000、10:10000、20:10000)was higher than control treatment and low dosage treatment obviously. The determination result of seedling physiological activity showed that pyraclostrobin treatment could increase chlorophyll content, enhance root activity, improve protective enzyme activities, soluble protein content of the maize leaves and root, enhance photosynthetic enzyme activities, decrease MDA content of the the maize leaves and root.3、A plot experiment in this paper was determined to study the effect of seed dressing with pyraclostrobin at the active principle/seed of 0.625:10000, 1.25:10000, 2.5:10000, 5:10000, 10:10000, 20:10000 on the growth and protective enzyme activities of the maize seedling. The result shows that compared with the contrast, 10:10000 ratio seed coating agent made the height、root number、fresh mass per plant、root-shoot ratio of the corn seedling increased by 39.9%, 1.3, 50.8%, 0.48 respectively, and 2.5:10000 ratio seed coating agent made the root length increased by 19.1%. Comparing with the contrast, treatment 2.5:10000 increased the leaf soluble protein content by 11.1% and POD, CAT activities by 37.9%, 27.2%, improved SOD, CAT, PPO, PAL activities by 12.2%, 64.7%, 13.3%, 26.7% and root activity by 61.6%; Treatment 5:10000 could increase SOD, PPO, PAL, PEPCase activities by 7.9%, 13.4%, 22.7%, 310.0%of the maize seedling leaf, decrease MDA content of the leaf by 49.4%;Treatment 10:10000 increased RuBPCase activity by 82.5% and the maize seedling’s chlorophyll content by 13.6% and POD activity by 130.0%, decrease MDA content of the root by 34.4%;The treatment of pyraclostrobin have no apparent influence on the root soluble protein content.The results showed that seed dressing with pyraclostrobin could promote the growth of the maize seedling.4、In this study, the effects of pyraclostrobin on the soil microbial respiration and the soil enzyme activities were determined. The direct absorption method was used to study the effects of pyraclostrobin and azoxystrobin on soil microbial respiration. The results showed that the prospect of pyraclostrobin on the soil microbial respiration was facilitation-stimulatio n-recovery during the whole process, and the respiration was recovered after 15 d. In the azoxystrobin treatment, the prospect was stimulation-inhibition-stimulation, and the effect was still exist after 15 d. The effects of the two fungicides on soil microbial respiration were evaluated by the hazard coefficient method, and it was found that the pyraclostrobin and the azoxystrobin posed a little risk to the soil microbial. To all of the concentrations of pyraclostrobin, the activity of soil urease 、 soil neutral phosphatase that treated with pyraclostrobin were inhibited, and the inhibitory effect increased with the increasing concentrations. The prospect of pyraclostrobin on soil invertase was inhibition-recovery. On 21 days, the effect of low concentration treatment(1 mg·kg-1) on soil invertase、soil urease、soil neutral phosphatase returned to the control level. All concentrations of pyraclostrobin had stimulatory effect on soil catalase, and the effect returned to the control level on 14 days. It showed that pyraclostrobin had different degrees of inhibitory or stimulatory effect on the soil microbial and the soil enzymes, and the effect recovered to the control level after a certain period of time. |
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