| With the increase area of the machine-transplanted rice, rice seedling-raising substrate becomes the development tendency for rice seedling cultivation technology because of its wide material sources, low production cost and strong compatable of mechanized transplanting technology. Thus to define the cultivation technology of different types of substrate, reveal the influence of substrate type characteristic on rice seedling and physiological characters, evaluate their adaptability and applicability, and explore exogenous regulation way to improve substrate seedling-raising quality and machine-transplanted rice yield, will be great important in promoting the popularization and application of rice seedling-raising substrate technology and improving the level of machine-transplanted rice. In this research, two main tests were carried out:(1)use Xiushui 321 as plant material, and light soilless substrate, mixed substrate and field soil(CK) as treatments, to explore the influence of characteristic of different seedling-raising substrate on rice seedling physiological characteristics, mechanized transplanting quantity, field growth and yield formation.(2) use Jia58 as plant material and set two seedling-raising substrate(nutrient soil and light soilless substrate), five seedling age treatments(12 d, 18 d, 24 d, 30 d and 36 d), and 2 uniconazole soaking concentrations(0 mg?L-1 and 25 mg?L-1) to explore the influence of diffenent substrate on seedling physiological characteristics and field growth of late rice and its regulation measures.1. The physical and chemical properties of different rice seedling-raising substrate were significant difference, Light soilless substrate and mixed substrate treatment was better than the control treatment. Volume-weight of light soilless substrate and mixed substrate were 85.19% and 74.07% lower than the control treatment, while the aeration porosity, water-holding porosity and their nutrient content were significantly higher than the control. Leaf age and plant height and shoot weight and shoot width showed advantage compared with that of the control treatment. Their seedling roots that could coil into a block and empty cone rate were less than 5%, and were 4.17% and 4.32% lower than the control, respectively. The injury seedling rate of light soilless substrate was 3.07%, which was not significant diffencnce with the control treatment, but significantly lower than the mix substrate.2. After transplanted for 7 d, root dry matter weight of light soilless substrate were 10.0% and 30.8% higher than the mixed substrate and the control treatment, shoot dry weight were higher by 7.8% and 25.7%, respectively. After transplanted for 14 d, light soilless substrate treatment was no significant with the mixed substrate, but was higher than the control by 7.8% and 25.7%. The initial tiller stage of light soilless substrate treatment was ahead for four days than that of CK, and mixed substrate was two days. From both substrates, rice had significantly more dry matter accumulation than that of the control treatment in all growing stages. The range of increased storage capacity was 14.01% and 10.67%, and yield was 5.30% and 6.14%, respectively. Light soilless substrate is made of crops, straw, which is easy to get and can be decomposed completely in soil. Moreover, lighter in weight of light soilless substrate helped to reduce labor intensity and lower in water content helped to prolong the storage life. The yield from light soilless substrate was almost the same with the mixed substrate treatment, but was significant higher than that of control. With the obvious application advantage above, light soilless substrate was better for the production and application of seedling substrate.3. With extension of seedling age, rice leaf age, plant height and shoot dry weight was significantly increased. Root shoot ratio significantly decreased. When the seedling age was more than 24 d, root growth was stopped, planting rate and field basic population decreased significantly, and empty rate and injury rate was significant increased. With rice yield increased first and then decreased with seedling age prolonging. 18 d seedling age is the highest yield treatment. When seedling age was from 18 d to 24 d, yield of nutrition soil treatment was significantly decreased, but light soilless substrate treatment was not significantly decreased. After 24 d seedling age, with seedling age prolonging, Spikelets per panicle, number of panicles and seed-setting rate dropped gradually, which led to the decrease of yield. Using Jia58 as rice varieties, nutrient soil ’s optimal transplanting seedling age was 18 d, while light soilless substrate’s was 18~24 d.4. Using 25 mg?L-1 uniconazole soaking treatment could improve rice seedling quality. The stem width of soaking treatment increased 0.1~0.2 mm. Plant height was significantly decreased, and chlorophyll content and root activity was significantly increased. When seedling age was less than 18 d, uniconazole soaking treatment influenced the mass of seedling and planting quality slightly, but when seedling age was longer than 24 d, uniconazole soaking treatment could effectively improve the planting percent and field basic population, and reduced empty rate and injury rate. When seedling age was less than 18 d, the effect of uniconazole soaking treatment was not obvious. When seedling age was longer than 24 d, uniconazole soaking treatment could improve the Spikelets per panicle and number of panicles, which led to an increase of yield. And with the prolonging of seedling age, yield-increasing effect was more remarkable. By using uniconazole soaking treatment, light soilless substrate had a slight improvement of seedling block, but was not affect the yield. |
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