| As an important economic crop, peanut is essily influenced by some adverse factors, such as diseases, pests, and hypothermia in the process of growth. Spraying fungicides and insecticides are commonly used to reduce the damage. Temperature and humidity have important effects on the growth of peanut seedlings. This paper mainly studies the effects of three fungicides(pyraclostrobin, kresoxim methyl and azoxystrobin) on peanut seed emergence and growth of seedling at different concentrations and selects the security dose with seed dressing. The three fungicides are used to seed dressing at the optimum dose in different humidity and different temperature. Under these conditions, the effects of temperature and humidity on peanut seed germination and seedling growth are researched by the measurement of biological characters and physiological and biochemical indexes of peanut seedling. The main results are summarized as follows:1. The effects of pyraclostrobin, kresoxim methyl and azoxystrobin on seed germination and seedling growth in peanut seed dressing are researched in different doses. The three fungicides have positive effects on the growth of peanut seedlings at four seed dressing doses(50, 100, 150, 200 g a.i./100kg(seeds)) one month later. According to the test results, the screened most suitable dressing dosage is 100 g a.i./100 kg seeds. At this dose, the plant height increased respectively by 19.3%, 15.7%, 15.4%; the length of root increased respectively by 26.7%, 26.1%, 8.9%; the ground fresh weight increased respectively by 26.3%, 12.5%, 21.3%; and the underground fresh weight increased respectively by 44.4%, 44.4%, 33.3%. At the same time, the activity of leaf protective enzymes(SOD, POD, CAT) and transaminases(GPT, GOT), chlorophyll content, soluble protein content and root activity increased, while malondialdehyde(MDA) content decreased. The three fungicides have a health function on peanut seedlings.2. The effects of pyraclostrobin, kresoxim methyl and azoxystrobin on seed germination and seedling growth in peanut seed dressing are researched in different temperatures. This study is conducted in 60% humidity and three temperatures(18, 20, 25 oC) at the dosage of 100 g a.i. /100kg(seeds). One month later, it is indicated that the plant height, main root length, above-ground fresh weight, underground fresh weight and the other agronomic characteristics of peanut plant all increased as temperature increased. The protective enzymes(SOD, POD and CAT) activity, transaminases(GPT, GOT) activity, chlorophyll content, soluble protein content and root activity improved, but MDA content and relative electric conductivity decreased. From the experiment, the best index is obtained at 25 oC. Due to the low temperature, seed germination and seedling growth are inhibited at 18 oC. The three fungicides can promote the growth of peanuts after seed treatment, which can reduce the harm of low temperature on peanut seedlings to a certain extent. The pyraclostrobin produced the best health function.3. The effects of pyraclostrobin, kresoxim methyl and azoxystrob on seed germination and seedling growth in peanut seed dressing are researched in different humidity. In this experiment, seed dressing used the three fungicides in the 100 g a.i./100kg(seed dressing) dose in three relative humidity(40%, 60% and 80%) at certain temperature(25 oC). One month later, the results showed seedling height, root length, ground fresh weight, underground fresh weight, protective enzyme activity, MDA content, transaminase(GPT, GOT) activity, chlorophyll content, root activity, and leaf relative conductivity rate achieved the best value in 60% humidity of each treatment. In 40% humidity conditions, peanut seedling emergence time increased by 2 days, and the plant height and aboveground fresh weight were all less than that in 80% humidity in each treatment. However the main root length, fresh weight and root activity of underground in 40% humidity were larger than that in 80% humidity. The physiological and biochemical indexes of leaf protective enzymes and aminotransferase under 80% humidity are better than that under 40% humidity. The analysis suggested that no matter in the condition of wetting soil as in 80% humidity or drying soil as in 40% humidity, the three fungicides still can promote the growth of peanut seedlings by seed treatment. In a word, three kinds of fungicides can reduce the effect caused by the low temperature, drought and soil humidity on peanut seedling. This study has a certain field application value in guiding the peanut seeder. |
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