| Green manure is a kind of clean and natural organic fertilizer source,which refers to overturning the fresh plants into field to improve the physical and chemical properties of the soil and nitrogen use efficiency of the subsequently crops,and promote the growth of the subsequently crops.The application of green manure is of great significance for the construction of an environment-friendly society and the sustainable development of agriculture.However,there were few reports on the effects of green manure application on subsequent colored and fragrant rice in tropical regions.Therefore,we have conducted a two-season field experiment in Guangji Village,Nanbao Town,Lingao County,Hainan Province from 2020 to 2021.The experiment set up four treatments:T0:the treatment of subsequent rice with previous fallow,T1:the treatment of subsequent rice with fresh rice straw manure;T2:the treatment of subsequent rice with sesbania manure;T3:the treatment of subsequent rice with stylosanthes manure.The effects of the four treatments on soil physicochemical properties,nitrogen uptake of subsequent functional rice,grain yield and functional substance content were investigated.The main results are as follows:1)20 days after the green manure was returned to the field,compared with T0,the content of total nitrogen increased by 10.3%,22.8%and 20.4%;the content of available phosphorus in the soils under T1,T2 and T3 were increased by 24.5%,34.6%and 38.4%;the content of available potassium increased by 28.3%,41.5%and 38.4%;the content of total organic carbon increased by 27.8%,46.8%and 37.8%;cation exchange capacity(CEC)increased by 6.5%,16.5%and 11.3%;respectively.In contrast,soil bulk density were decreased by 8.1%,14.2%and 12.4%,respectively.2)The green manure overturned and returned to the field,which significantly promoted the growth and development of the subsequent rice.The plant height,tiller number or effective panicle number,aboveground dry weight and SPAD value of the subsequent rice under the treatment of green manures overturned to the field(T1,T2 and T3)were significantly higher than those under T0.At maturity stage,compared with T0,the effective panicles of Haixiang 309(HX309)and Suixiangheinuo(SXHN)were increased by 8.3%,19.7%and 18.2%,and 15.5%,28.0%and 25.5%under T1,T2 and T3,respectively.At the same time,the aboveground dry weight of HX309 and SXHN were increased by 10.7%,28.3%and 41.4%,and 20.8%23.8%and 39.6%under T1 T2 and T3,compared with T0,respectively.3)The green manure overturned and returned to the field promoted the nitrogen uptakes of subsequent rice and improved nitrogen use efficiency.The plant nitrogen4)content and nitrogen absorption of the subsequent rice under T1,T2 and T3 were significantly higher than that of T0.Compared with T0,the nitrogen partial productivity(PFP_N)of HX309 and SXHN were increased by 14.5%,43.9%and 28.8%,and 11.4%,37.0%and 28.7%under T1,T2 and T3,respectively.5)The green manure overturned and returned to the field significantly increased the grain yield of subsequent rice.Compared with T0,the grain yield of HX309 and SXHN were increased by 13.2%,29.1%and 23.9%,and 12.5%,28.7%and 25.3%under T1,T2and T3,respectively.6)Green manure overturned and returned to the field significantly increased the functional substance content of the subsequent rice.Compared with T0,the grain anthocyanin content and flavonoids content of SXHN increased by 7.4%,19.1%and15.2%,and 25.2%,36.8%and 35.2%under T1,T2 and T3,respectively.The average total antioxidant capacity of T1,T2 and T3(2.43μmol/m L,2.71μmol/m L and 2.57μmol/m L)and the average hydroxyl radical scavenging rate(58.7%,62.7%and 63.1%)were significantly higher than that of T0(2.19μmol/m L and 49.4%).The aroma substances(2-AP)of HX309 under T1,T2 and T3 were increased by 50.6%,107.1%and 125.0%,respectively,compared with T0.In conclusion,overturning of legume green manure into the soil not only improved the soil physical and chemical properties,but also significantly promoted the growth and development,nitrogen uptakes,grain yield and functional substance content of subsequent functional rice. |
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