【作者】 李小勇；

【导师】 唐启源；

【作者基本信息】 湖南农业大学 ， 作物栽培学与耕作学， 2011， 博士

【摘要】 为了挖掘南方双季稻田的粮食生产潜力和保障粮食安全,应对因全球气候变暖引发的南方季节性干旱问题,促进南方稻区“粮-经-饲”结构协调发展,提高稻田生产系统的综合效益,促进稻区农业可持续、健康和低碳发展,为稻田种植结构的战略性调整提供科学依据,本研究在高产栽培条件下,以传统双季稻种植模式(R-R)为对照,通过2年大田定位试验和土壤-作物系统相结合的方法,比较系统地研究了稻田“春玉米-晚稻”种植模式(M-R)的生产力、资源利用效率及氮素利用特征；土壤背景供氮对M-R模式土壤养分特征的影响及不同施氮水平和耕作方式对M-R模式中晚稻产量形成的影响,其主要研究结果如下：1.M-R模式的周年生产力和资源利用效率优势显著,与传统R-R模式比较,产量和物质生产效率分别提高了20.0%和23.2%；土地资源利用率,光、温、水资源生产效率和光能利用率分别提高了9.75%,14.7%,20.4%,12.1%和19.1%；周年总产值和产投比分别提高了16.7%和8.04%,体现了M-R模式高产高效和资源高效利用的特点。2.M-R模式的N肥利用效率与R-R模式不同。与传统R-R模式比较,M-R模式的周年氮素收获指数提高3.01%～3.98%；氮肥籽粒和干物质生产效率分别提高10.8%～12.6%和12.7%～20.6%,氮肥吸收利用率(RE)增加13.0%-20.3%,而氮肥偏生产力(PFP)、农学利用率(AE)和生理利用率(PE)偏低,但与R-R模式差异均不显著。3.与R-R模式的连作晚稻比较,采用同一耕作方式,M-R模式的晚稻产量增幅为2.13%～6.47%;增产原因主要是由于叶面积指数增加,抽穗后剑叶的叶绿素含量(SPAD值)和PSⅡ的光化学量子产量(EQY)提高,热耗散(qN)降低,表现出光化学利用效率优势,最终使晚稻总干物质重增加了3.7%～6.8%。与常规翻耕栽培(CT)比较,免耕移栽(NT)使M-R模式的晚稻产量显著增加10.5%,增产效应显著的原因在于单位面积有效穗和颖花量增加(8.53%和6.77%)；采用翻耕+秸秆碳(CTC)、翻耕+秸秆还田(CTS)处理可使M-R模式晚稻产量分别增加6.4%和3.3。4.采用同一耕作方式,M-R模式晚稻收获后土壤全量养分与R-R模式比较,差异不显著；但速效钾、速效磷和碱解氮(CTC除外)有不同程度提高。正常翻耕条件下,与R-R模式比较,M-R模式晚稻收获后土壤有机质含量降低了4.44%,且土壤pH值略有降低；采用免耕、秸秆还田和添加生物碳等措施可使土壤有机质含量分别提高10.8%,3.41%和44.4%。5.与R-R模式的连作晚稻比较,采用同一施氮水平,M-R模式的晚稻产量增加2.41%～6.32%,增产的原因主要是每穗粒数和单位面积颖花量的增加,生育后期(齐穗期后15天)LAI提高了1.34%～17.5%,叶片SPAD值提高0.75%～2.64%,剑叶净光合速率(Pn)提高7.77%～11.1%；同时提高PSⅡ的EQY和电子传递速率(ETR),降低热耗散(qN),辐射利用率(RUE)提高,最终使总干物重增加(1.64%～4.22%)而增产。6.在低土壤背景氮下,与NoNo比较,M-R模式NoN处理的晚稻产量显著增加41.8%,增产原因在于施氮处理显著提高了单位面积有效穗,在生育后期,LAI和叶片的SPAD显著提高了52.0%和13.0%；剑叶Pn明显提高13.2%、EQY、ETR和qP上相对优势较大,qN较低,RUE提高了4.49%；最终导致总干物质积累量显著提高了21.2%；高土壤背景氮下,与NN比较,M-R模式NNM处理的晚稻产量提高了4.73%,增产原因在于单位面积颖花量和有效穗的增加。7.晚季不同土壤背景供氮下,采用同一施氮水平,与R-R模式比较,M-R模式晚稻收获后的土壤有机质和全N含量降幅分别为5.44%～15.1%和1.4%～10.3%；土壤pH值略升高；在低土壤背景氮下,碱解氮、速效磷和速效钾含量分别平均降低了4.65%,13.7%%和10.5%；在高土壤背景氮下,碱解氮平均增加2.33%,速效钾平均降低了12.0%。在两季不施氮肥情况下,M-R模式的晚稻土壤碱解氮含量比R-R模式降低了9.30%,晚季增施氮肥能明显提高其土壤有机质和碱解氮含量,但会降低速效钾和速效磷含量,在两季施氮情况下,土壤碱解氮则提高了2.5%,晚季增施有机肥能明显提高其土壤有机质和全N含量,但降低土壤速效养分含量,特别是速效钾的含量。8.整个生育期间,M-R模式晚季稻田土壤养分含量变化表现出与R-R模式一致动态特征：土壤pH呈“先降后升,再略降低”的趋势；有机质含量表现为“先升高后降低,再略升高”的趋势；全量养分含量变化较小；在低土壤背景氮下,速效养分含量均呈“先持续下降,后略升高”的趋势；在高土壤背景氮下,土壤速效钾和速效磷与低土壤背景氮的趋势一样,而碱解氮呈“先持续下降后升高,再略下降”趋势。更多还原

【Abstract】 The major objective of this study was for exploring the productive potentials in double rice cropping system in South China so as to ensure food security, deal with seasonal drought problems caused by global climate warming in South China, promote harmony development of the "grain crop-cash crop-feed crop" structure, enhance the comprehensive benefits in rice field productive system, accelerate sustainable, healthy and low carbon development of the agriculture as well as provide scientific accordance to strategic adjustment of the current rice field planting structure. This study was conducted under high yield cultivation conditions on a fixed field for 2 years with conventional double-rice cropping model (R-R) as check by a method of combination of soil with crop system. We discussed the annual productivity, resource use efficiency and nitrogen utilization characteristics in "spring maize-late rice" rotation pattern (M-R), analyzed the effect of background soil nitrogen supply on annual soil nutrient property and the dynamic changes in M-R planting pattern as well as the effects of different applied-N levels and tillage methods on yield formation of late rice in M-R cropping system. The main results were as follows:1. The experiments showed that M-R model had significantly advantages in annual productivity and resource use efficiency over the conventional R-R model. The annual yield and matter production efficiency in M-R model increased by 20.0% and 23.2%, respectively, compared to the traditional R-R planting model. And the annual soil resource use efficiency, the production efficiency of light, temperature, and water resources as well as radiation use efficiency (RUE) also increased by 9.75%,14.7%,20.4%,12.1% and 19.1%, respectively. Furthermore, the annual total output and the ratio of output/input increased by 16.7% and 8.04%, respectively. These results indicated that the M-R model was of higher yield, higher efficient and higher resource use efficiency.2. The results also showed that nitrogen fertilizer use efficiency in M-R planting model differed from that in R-R planting model. The M-R planting model was much better than R-R planting model in terms of nitrogen recovery efficiency (RE) and productive efficiency. The nitrogen recovery efficiency, whole nitrogen grain and matter production efficiency increased by 13.0%-23.0%,10.8%-12.6% and 12.7%-20.6%, respectively; the nitrogen harvest index (NHI) increased by 3.01%-3.98%; whereas the nitrogen partial factor productivity (PFP), agronomy use efficiency (AE) and physical utilization those of R-R planting model even these were not at significant level. 3. With same tillage method, compared to late rice of R-R planting model, the yield of late rice of M-R planting model increased by 2.13%-6.74%. The reasons for the yield increase were due to the increase of leaf area index (LAI), and the enhancement of the SPAD value and the effective PSⅡquantum yield (EQY) of flag leaf, the reduction of the non-photochemical quenching index (qN) after heading stage in M-R planting model, as well as the good performance of the photochemical utilization efficiency, which led to 3.7%-6.8%increase of the final total dry matter accumulation of M-R planting model at maturing stage. Moreover, compared with conventional tillage (CT) treatment, the yield of late rice under no-tillage(NT) treatment in M-R increased by 10.5%, which reached significant difference. The reasons for this yield increasing came from both the effective tiller number and spikelet number per unit area increases (by 8.53% and 6.77%, respectively); The yields of late rice in conventional tillage+ carbon(CTC) treatment, in conventional tillage+ straw-retuning to field(CTS) treatment under M-R planting model could be increased by 6.4% and 3.3%, respectively.4. There had no significant differences in soil total nutrient content including total N, total P and total K after late -season rice harvest between M-R cropping system and traditional R-R cropping system. However, the soil available K and available P contents got some improvements. Under conventional tillage method, the soil organic matter content after late rice harvest in M-R cropping system decreased by 4.44% coupled with the soil pH value lowering compared to the R-R cropping system. With no-tillage in straw-retuning to field and organism carbon application treatments, the soil organic matter content in M-R cropping system could be increased by 10.8%,3.41% and 44.4%, respectively.5. Compared with R-R planting pattern with the same N fertilizer rate, the yield of late rice in M-R planting patter increased by 2.41-6.32%. The reasons for increasing yield were due to the increases of grain number per hill and spikelets number per unit area. Also compared with R-R planting pattern during late growth stage (15 days after 80% heading), the leaf area index(LAI) of M-R planting patter was 1.34% to 17.5% higher; the SPAD value of flag leaf of M-R planting pattern,0.75% to 2.64% higher; the net photosynthetic rate (Pn)of flag leaf in M-R planting model,7.77% to 11.1% higher. Meanwhile, M-R planting pattern showed much better in terms of effective PS II quantum yield (EQY), electron transports rate (ETR) and coefficient of photo-chemical quenching (qP) which can reduce the coefficient of non-photochemical quenching (qN), and enhance the radiation use efficiency (RUE), and contributed the final total dry matter weight of M-R planting pattern to an increase of 1.64 to 4.42% over R-R planting pattern. 6. Compared with NoNo under low indigenous soil N-supply, the yield of later-season rice of the NoN treatment in M-R planting pattern increased significantly by 41.8% due to the effective panicle number per unit obviously increase by N-fertilizer application; the LAI and the SPAD value of flag leaf in the N0N treatment were 52.0% and 13.0% higher, respectively, during later growing stage; the net photosynthetic rate (Pn)of flag leaf of NoN treatment was 13.2% higher during later growth stage; the effective PSⅡquantum yield (EQY), electron transports rate (ETR) and coefficient of photo-chemical quenching (qP) which can reduce the coefficient of non-photochemical quenching (qN) showed strong advantage; the radiation use efficiency(RUE) was 4.49% higher. All these contributed to an increase of the final total dry matter accumulation of NON treatment at maturity stage to 21.2%, reaching significant difference. While under high indigenous soil N-supply, the yield of the late rice of NNM treatment in M-R planting pattern increased by 4.73% due to the effective panicle number increase and the spikelets increase per unit area.7. Under different indigenous soil N-supply for later -season rice, the total soil N content and organic matter content in M-R cropping pattern with same N-fertilizer application rate decreased by 1.4%-10.3% and 5.44%-10.5%, respectively, compared with R-R planting pattern. However, the soil pH value of M-R model was higher than that of R-R model. Under low indigenous soil N supply, the available soil nutrients including available N, available P and available K in M-R cropping system decreased by 4.65%, 13.7% and 3.04%, respectively, compared with traditional R-R planting model. However, with high indigenous soil N supply, the content of available N in M-R cropping pattern was 2.33% higher but 12.0% lower of the content of available K compared with R-R planting model. With zero N-fertilizer application to the 2 cropping seasons, the content of soil available N after later-season rice harvest in M-R cropping pattern was 9.30% lower than that R-R planting model, and N application to second cropping season could dramatically increase the soil organic matter and soil available N content, but decrease the soil available K content. With N-fertilizer application to 2 cropping seasons, the content of available N after later-season rice harvest in M-R cropping pattern increased by 2.50% compared with R-R planting model, and organic fertilizer application to the second season in M-R cropping pattern could enhance the soil organic matter and the total N contents, but decrease the soil available nutrient contents, especially for the soil available K content.8. During whole crop growing season in late rice field, the dynamic change tendency in soil nutrient contents appeared the same both in M-R and R-R planting system:soil pH value showed a tendency curve like "down-up-down"; the soil organic matter content showed a tendency curve like "down-up-stable finally"; the total nutrient content showed constant; with low indigenous soil N, the available soil nutrient content in M-R planting pattern showed a trend curve like "up-down "; with high indigenous soil N, the available soil K and available P in M-R planting pattern had the same tendency as with low soil N background; the available N content in M-R planting pattern showed a tendency curve like "down-up-down".更多还原