Super High Yield Cultivation And Its Control Measures In Rice

Rice is the most important food crop, which is looked on as staple food by 50% of the population in the world. Breeding in rice have made great progress, while studies on super high yield cultivation are more and more paid attention. Therefore, there are some important meanings in improving nitrogen use efficiency and saving irrigation in rice by using suitable agronomic measures. Field experiments were conducted by taking different agronomic measures and designing a series of field experiments(such as the experiment on the qualities of rice seedling, transplanting density, nitrogen management, actions between water and nitrogen, super high yield in the large area) during 2005-2009. Rice population was constructed in different yield levels to study biology characteristics, nutrition absorption, water use efficiency, yields and grain qualities in rice. Main skill indexes are analyzed and plant systems are brought forward in super high yield cultivation of rice. Some main results are as follows,1. The influences of seedling quality and transplanting density on biology characteristics and yield in rice.Compared by rice seedling with 2,3 tillers per plant, transplanting rice seedlings with 4,5,6 tillers per plant could increase biomass at different growth stage, improving productive panicle per m2 and the number of spikelets per panicle and seed setting rate, raising the yield in rice. When the age of transplanted seedlings were older, LAI at the growth stage were fewer, which could induce significantly fewer biomass at the late stage and lower yield in rice. Therefore, the old-age-seedlings(age≥50 days) were transplanted, productive panicle per m2 and yield were noticeably raised by increasing transplanting density and the numbers of seedling per hill in rice.2. The influences of actions between water and nitrogen fertilizer on yield, grain qualities and water use efficiency in rice.There were significant differences in the yield and productive panicle per m2 under different water regimes. Rice yield and productive panicle per m2 under alternate wetting and drying irrigation (W2) and raised-bed irrigation (W3) were higher than that under traditional flooding (W1). Remarkable differences were also found in the yield, panicle number, panicle length, the first branch, total spikelets per panicle, solid grain spikelets per pernicle and seed setting rate among nitrogen treatments. However, there was no significant difference in 1000-grain-weight. Furthermore, obvious effects of interaction were discovered between water and nitrogen on productive panicle per m2.There were remarkable differences in BRR and GC (Gel consistency) among different water regimes. BRR and GC were higher in W3 than other treatments, which were 76.25% and 64.16 mm, respectively. There were higher trends in BRR and MRR and HMR and PC as the increase of more nitrogen applied in the 0-270 kg N/hm2. Opposite trends were found in AM and GC. There were significant effects of interaction between water and nitrogen on rice CP and PC and GC.There were significant differences in the volume of irrigation water and water use efficiency. The volume of irrigation water was less in W2 and W3 than W1 treatment, which were 299.40,310.62 and 408.65 mm, respectively. And there were opposite trends in water use efficiency, which was 1.56,1.60 and 1.21 kg/m3, respectively. Significant differences were found in water use efficiency among nitrogen treatments, which were in ranges of 1.06-1.96 kg/m3. Water use efficiency was higher in the treatment of 180 kg N/hm2, which was 1.71kg/m3.3. The influences of nitrogen management on biology characteristics, yield, quality and nutrition use efficiency in rice.(1) The influences of nitrogen managements on yield and quality in rice.More nitrogen applied in the range of 0-330 kg N/hm2 could remarkably increase leaf area index (LAI) at panicle initiation stage (PI) and LAI and leaf areas of high efficiency ratio to population area at heading stage (H) in rice at a nitrogen ratio for basal fertilizer (BF):first topdressing fertilizer (FT):second topdressing fertilizer (ST)=30%:20%:50%. It was increased in total biomass at the growth stage and dry matter translocation before heading, then, contribution of pre-anthesis assimilates to seed was also raised. Rice yield was increased firstly and then dropped as the increase of nitrogen applied in the level of 0-330 kg/hm2. There was the maximum values in yield, productive panicle per m2, total number of spikelet per panicle and 1000-grain-weight, which were 10.31 t/hm2,400.1×104 panicle per hm2,221.39 spikelets per panicle and 29.78 g, respectively, by using BF:FF:SF=30%:20%:50% at 240 kg N/hm2.Increase of nitrogen application in the range of 0-330 kg N/hm2 could improve brown rice rate (BRR), milled rice rate (MRR), head milled rice rate (HMR), protein content (PC) and chalkyness (CN) in rice. However, there was opposite trend in amylase (AM). Compared by using BF:FT:ST=40%:30%:30%, PC was increased and amylase (AM) was decreased remarkably by using BF:FT:ST=30%:20%:50%. There were also distinctly positive correlations between BRR and MRR and HMR and PC, which were 0.6201,0.7213,0.5062, respectively. However, Remarkably negative correlation was found between PC and AM, which was-0.6003.(2) The influences of nitrogen managements on the absorption of nutrition and nitrogen(15N) derived from fertilizer (Ndff) by using label isotope urea(15N) in rice.Nitrogen applied could increase remarkably total nitrogen accumulation (TNA), total phosphorus accumulation (TPA) and total potassium accumulation (TKA) at maturity stage (M) in 0-240 kg N/hm2. Furthermore, the absorption of Ndff and nitrogen derived from soil (Ndfs) were also raised, too. There were TNA, Ndfs and Ndff in the treatment of 240 kg N/hm2 as for 176.15,150.09,110.25 kg/hm2, more than those of 100.13, 65.91 and 49.97, in 150 kg N/hm2. Moreover, the residual amount of Ndff in the soil was remarkably increased, which was 32.69 and 24.92 kg/hm2. Compared by using BF: FT:ST=40%:30%:30% treatment, TNA at H and M and nitrogen recovery efficiency and agronomic efficiency were obviously increased, as well as residual rate of Ndff in the soil by using BF:FT:ST=30%:20%:50% treatment. Unaccounted rate of Ndff was also decreased, too.(3) The influences of nitrogen management on the absorption of basal fertilizer (15N) and topdressing fertilizer (15N) in rice.More fertilizer applied in 0-330 kg N/hm2 could increase remarkably basal fertilizer (15N) and topdressing fertilizer (15N) at the growth stage in rice. The amounts of basal fertilizer (15N) absorbed at mid-tillering stage (Mt) and PI and H were much higher in the treatment of 330 kg N/hm2 by using all fertilizer applied as basal fertilizer application than other treatments. There was more topdressing fertilizer (15N) absorbed by using BF:FT:ST=30%:20%:50% treatment than BF:FT:ST=40:30%:30%. The ratios of basal fertilizer (15N) absorbed at Mt and M were in ranges of 11.94%-26.12% and 12.31%-27.82%, respectively. However, the ratios of basal fertilizer (15N) absorbed at PI and H were in ranges of 30.36%-33.24% and 27.78%-30.34%, respectively.(4) The influence of nitrogen managements on the nitrogen concentration in the surface water and leachate from rice field.There were obviously positive correlations between nitrogen concentrations of NH4+-N and total nitrogen (TN) in the surface water, moreover, positive correlations were found between nitrogen concentrations of NO3--N and TN in the leachate. All correlation coefficients were more than 0.8105.Compared by using BF:FT:ST=40%:30%:30% treatment, the concentration of NH4+-N in the surface water and NO3--N and TN in the leachate were remarkably decreased by using BF:FT:ST=30%:20%:50% treatment.4. Main population indexes of super high-yield rice.There were some biology characteristics in super high yield rice (yield≥12.0 t/hm2) than high yield rice (yield>9.0 t/hm2). The first aspect:yield and its components. As productive panicles≥250×104 per hm2, productive tiller percentage>68.0%, seed setting rate≥88.2%,1000-grain-weight>29.0 g. The second aspect:LAI at different growth stage. LAI at Mt, PI, H and GF were 30.-3.5,6.5-7.2,8.5-8.9 and 6.5-7.0, respectively. Ratio of leaf area of high efficiency at H was about 60.0%-66.5%. The third aspect:total biomass. Total biomass at Mt, PI, H, GF and M was 21.-2.5,8.5-10.0,≥13.5,≥15.0 and≥25.0 (t/hm2), respectively.