【作者】 龙继锐；

【导师】 马国辉；

【作者基本信息】 湖南农业大学 ， 作物栽培学与耕作学， 2008， 博士

【摘要】 随着超级杂交稻的广泛推广应用,日益凸现出二个重要问题:一是超级杂交稻需肥量大,引起水稻生产上氮化肥用量的大幅增长,过量的化肥造成了一系列社会和环境问题;二是由于栽培技术不配套,品种超高产潜力一直难以发挥。为此,我们以超级杂交一季稻为对象,以节氮高效栽培为目标,采用大阳试验方式,开展了一系列超级杂交稻节氮增效栽培试验研究。主要研究结果如下:1.湖南省超级杂交一季稻产量和氮肥施用现状湖南省超级杂交一季稻产量在7.50～9.75t/hm²之间,施氮量225.0～240.0kg/hm²（折纯氮）,最高施氮量超过270.0kg/hm²,属高施氮水平。加强超级杂交稻一季稻氮肥管理,减少施氮总量、提高产量空间较大。超级杂交一季稻节氮栽培施氮基准水平为225.0kg/hm²。2.超级杂交中籼稻氮高效利用基因型差异比较与筛选不同基因型组合的氮收获指数、氮素转运指数、氮籽粒生产效率和100kg籽粒需氮量变异大小次序是:氮收获指数＞氮素转运指数＞氮籽粒生产效率＞100kg籽粒需氮量。氮响应度变幅-2.86～31.06kg/kg。试验组合可以分为3种类型,第Ⅰ类:氮高效型。氮高效型又可以分为2种类型,即高效吸收利用型和耐低氮型。第Ⅱ类:适氮高产型。第Ⅲ类:高氮高产型。3.缓/控释肥等不同类型肥料氮利用效率的比较与评价缓释尿素（SCU）、缓释复合肥（CCF）、微生物肥（LPK/MF）、高效复合肥（LNPK）等肥料产量、氮肥利用率均较普通尿素不同程度提高。肥料SCU表现突出,2种氮水平下均较普通尿素显著增产,增幅分别为14.7%～23.9%和10.3%～11.9%,其氮肥生理利用率（PE）超过40kg/kg、农学利用率（AE）在23kg/kg以上,分别比普通尿素提高7个、8个百分点。同种肥料节氮处理高峰苗显著降低,成穗效率显著提高,中后期根系活力强、光合效率高,库充实较好,不显著减产。氮肥利用率也提高,氮肥生产力（PFP）、氮肥生理利用率（PE）、农学利用率（AE）、氮素籽粒生产效率（NGPE）、氮收获指数（NIH）分别较等氮处理提高20%、3.4～7.2%、3.6～9.6%、4.5～8.5%、10%。4.不同节氮栽培条件下超级杂交稻群体发育、物质生产、产量、养分吸收利用、氮肥利用效率和土壤氮积累效应节氮幅度提高水稻分蘖发生速度降低,同最大茎蘖增长速率下降,日茎蘖增长饱和期（茎蘖同增长速率为0时间）提前,分蘖终止期提早,分蘖总数下降,前期生长略显不足,有效穗数减少,一定范围内（节氮40%内,氮量135kg/hm²）减少不显著,高峰苗数显著降低,成穗率大幅度提高。群体生产率（CGR）随氮水平增加而提高。最大CGR变化幅度为17.51～35.89 kg.hm^-2.d^-1。分蘖-幼孕分化穗、穗分化-孕穗、孕穗-齐穗、齐穗-成熟4个阶段水稻CGR与产量相关系数依次为0.6324（P＞0.05）、0.7894（P＞0.05）、0.9722（P＜0.01）、0.9359（P＜0.01）。节氮幅度提高水稻生长干物质积累量减少。生长前期处理差异不显著,生长中期差异加大,一定节氮范围内（节氮40%,氮量135kg/hm²）,减少不显著。抽穗后,节氮处理生物产量明显降低,但其茎鞘物质输出率和转换率均显著提高。产量随施氮量增加呈单峰曲线变化,以节氮20%（180kg/hm²）处理最高,达到12.0t/hm²。植株对NPK的吸收均有2个高峰,吸收总量均随施氮量增加而增加,齐穗后植株还能吸收30%左右的氮素;植株吸收磷素以移栽到分蘖中期吸收最多;钾素吸收高峰在生育后期,节氮可提高生育后期植株钟素吸收比例。节氮大幅度提高氮肥利用率。节氮20%～60%RE超过42%、AE在20kg/kg以上、PE超过38kg/kgN,NHI在67%以上,100kg籽粒需氮量1.53～2.19kg之间。土壤总氮、速效氮量均随施氮量增加而提高。低氮处理土壤总氮和速效氮量均大幅下降;中氮处理两者均基本持平;高氮处理则均大幅增加。节氮能降低土壤速效磷水平,一定范围内节氮土壤钾含量不显著降低,并能提高有机质含量,减轻环境压力。5.不同节氮栽培条件下超级杂交稻生理生化、光合作用特性施氮量与叶片叶绿素含量呈显著正相关;叶片单位叶绿素的光合作用效率随施氮量增加先升高后降低;节氮能提高叶片单位叶绿素的光合作用效率。根系活力、叶片NR、GS、CAT等酶活性均随施氮量增加先增后降;MDA含量随施氮量增加呈先减后增变化。生育期后移根系活力、CAT酶活性均下降,MDA含量与此相反,GS、NR酶活性则先高后低,均以齐穗期最高。增施氮肥能提高剑叶净光合速率（Pn）、蒸腾速率（Tr）、气孔导度（Gs）;细胞间隙C02浓度（Ci）则随施氮量增加先降后升。适宜节氮能提高水稻叶片最大光合速率、降低光抑制系数、提高叶片光饱和点,不影响或不显著影响叶片捕光能力。叶片光合电子传递（ETR）、有效量子产量（EQY）和光化学猝灭系数（qP）,非光化学猝灭系数（NPQ）均受氮用量和光照强度双重影响;节氮能提高水稻叶片ETR、EQY和qP,氮肥过低或过高都会产生相反作用,NPQ随施氮量增加而提高:ETR、EQY、qP随生育期推进而提高,NPQ则相反。6.超级杂交一季稻节氮栽培关键技术平原地区超级杂交中稻节氮栽培策略:主攻有效穗,兼顾穗粒数和粒重。节氮栽培最佳施氮量135～180kg/hm²,N:P:K=1:0.4～0.7:0.9～1.2,移栽密度为18.0～21.0万蔸/hm²。超级杂交稻节氮栽培技术要点:品种氮高效、氮肥控缓释、壮秧栽小苗、小蔸适稀植、水肥长藕合、综合控病虫、防倒保高产。更多还原

【Abstract】 The Chinese Ministry of Agriculture has established 12 years ago a national collaborative research programme on breeding of super high-yielding rice（super rice）.But while China has been successful in breeding super hybrid rice（SHR） strains,it now faces two challenges in developing the super rice:1) because of its higher biomass,SHR.consumes more fertilizers leading to the rapid increase in N fertilizer use,and subsequently causing a series of social and environmental problems;2) the yield potential of super-high-yield varieties could not be attained due to lack of proper cultivation techniques.For these reasons,field experiments were conducted in Changsha,Hunan province in 2006 and 2007 to study N-saving and high-efficiency cultivation of the super hybrid single rice（SHSR）.The main results were as follows:1.Yield of SHSR and status of N application in HunanIn Hunan,yields of SHSR ranged from 7.50～9.75 t hm-² Actual yields of 8.25～9.00t/hm² were obtained relative to the variety yield potential of 12.0t/hm².Despite the relatively high level of N application ranging from 225.0kg/hm²～270kg/hm²,a yield gap of 2.25～4.50t/hm² existed. Thus,Hunan has still a long way to go to improve yield and N-use efficiency of SHSR The basic level of application for N-saving and high-efficiency cultivation of SHSR should be set as 225.0 kg N/hm².2.Genotypic differences in N-use and uptake among super hybrid and middle-season indica rice varietiesResults of this study showed that the order of N harvest index（NHI）,N transformation index（NTE）,N in grain production efficiency（NGPE） and the N amount needed by 100 kg grain of different genotypes was:NHI＞NTE＞NGPE＞the N amount needed in 100 kg grain.The range of response to N was-2.86～31.06 kg/kg.SHSR.combinations can be divided into 3 types:1) the high N use-efficiency type which can be further subdivided into 2 namely,the high- absorption and use efficiency and low N-tolerance types;2) high yield type with suitable N; 3) high yield type with high N.The low N treatment significantly caused low yield to a greater extent.3.Efficiency of N application using different fertilizers.The grain yield and N uptake and use-efficiency of Sulphur-Coated-Urea（SCU）, Coated-Compound-Fertilizer（CCF）,LPK/MF and LNPK under two N levels（N-saving and N-equivalent） were much higher compared with the ordinary urea..SCU increased yields by 14.7%～23.9%at 135 kg/hm² and 10.3%～11.9%at 187.5 kg/hm² and had high- N use efficiency.The Physiological efficiency（PE） was over 40 kg/kg and Agronomical efficiency（AE） over 23 kg/kg outweighing ordinary urea by more than 7%and 8%,respectively. Tillering rate,tiller number,effective panicle,photosynthetic leaf area,and dry matter accumulation of super hybrid rice under N-saving condition were lower than those of N-equivalent condition.The maximum tillers and stems significantly decreased,however,the percentage of effective panicle significantly increased.Moreover,the super hybrid ricer had much higher root activity in the middle and late growth stage,higher photosynthetic efficiency, good grain filling and increased number of filled grains.Nitrogen-saving treatments greatly improved N uptake and use-efficiencies,and increased Partial factor productivity（PFP） by 20%, PE by 3.4 to7.2%.AE by 6 to 9.6%,NGPE by 5 to 8.5%,and NIH by 10%.4.Crop growth and development,dry matter production,yield,nutrient uptake,N use efficiencies and soil N accumulation of SHSR under different N-saving treatments.At the range of N applied rate in this study with N level decreasing,tillering rate decreased and the maximum rate and the saturation date of tillering（the tillering rate was 0） and tiller production shortened,the total number of tillers and effective panicles decreased but not significantly.At 135 kg N/hm²（≤40%N-saving）,the maximum tillers and stems decreased significantly but the percentage of effective panicles substantially increased.Crop growth rate（CGR） increased with increasing N level.The maximum rates of CGR ranged from 17.5 to 35.9 kg hm^-2d^-1.The correlation coefficients between CGR and grain yield at different stages were as follows:tillering stage（TS） to panicle initiation stage（PI） r= 0.6324 （P＞0.05）,PI to booting stage（BT） r= 0.7894（P＞0.05）,BT to full heading stage（FH） r=0.9722（P＜0.01）,and FH to maturity（MA） r=0.9359（P＜0.01）.The dry matter accumulation decreased with N level decreasing.No significant differences in biomass among treatments at the early growth stage,but differences at the middle growth stage were observed except at 135 kg N/hm²（≤40%N-saving）.Biomass of N-saving treatments decreased significantly after heading,but with significantly higher amounts and rate of transformation of stem material,sheath material.Grain yield linearly increased with the increasing N application.Maximum yield of 12.0 t/hm² was obtained from the 20%N-saving treatment（180 kg N/hm²） Yield differences between the no N and with N treatments were significant.The yield of N3 treatment was significantly higher than those of the other treatments,except for N4 and N5.Yield differences among N4,N5, N2 were not significant,but their yields were significantly higher than that of N1.Uptake of NPK for SHSR had two peaks.The total N uptake increased gradually with increasing N rate.After heading,the total N uptake of SHSR was about 30%.The rate of N increase in straw was higher than that in grain.The maximum phosphorous uptake was at the middle tillering and potassium just after full heading stages.The percentage K uptake at the later growth stage increased under N-saving cultivation.Nitrogen-saving substantially increased N use efficiency.At 20%to 60%N-saving, Recovery efficiency（RE） increased by more than 42%,AE＞20 kg/kg,PE＞38 kg/kg N,and NHI＞67%.The amount of N required in producing 100 kg grain ranged from 1.53 to 2.19 kg.Effect on soil N accumulation:the total and available N in soil increased with increasing N application.Total and available N in soil of low N treatments significantly decreased,those of the middle N treatments were similar;and those of high N treatments increased significantly. 5.Physiology,biochemistry and photosynthetic traits of super hybrid rice under N-saving cultivationSignificant positive correlation between the chlorophyll content in leaf-area and the amounts of N applied was observed The efficiencies of the chlorophyll content per unit in leaf-area changed from high to low with the increase of N application rate.N-saving treatment could increase efficiencies of the chlorophyll content per unit in leaf-area.Root activities,the activities of NR,GS,and CAT in SHSR.leaves decreased with increasing amount of N applied.The content of MDA in leaves initially decreased and then gradually increased with N application.Root and CAT activities decreased but MDA content increased with growth stage.On the contrary,the activities of GS and NR decreased and reached the maximum at full heading stage.The Pn,Tr,Gs in rice flag leaf increased with increasing rate of N fertilizer.The Ci initially increased and then declined N increased.Optimal range of N-saving improved the maximum photosynthetic rate,reduced the coefficient of light inhibition,and increased light saturation point,but had little or no significant effects on the light absorbing abilities of the rice leaf.Photosynthetic electron transport（ETR）,the effective quantum yields（EQY）,photochemical quenching coefficient（qP）,and non-photochemical quenching coefficient（NPQ） in rice leaf were affected by the amount of N and light intensity.Nitrogen-saving increased but too low or too high N fertilizer decreased ETR,EQY.and qR Non-photochemical quenching coefficient was a positively correlated to the amount of N applied at 10d after full heading（0.9231,P＜0.05）.Except for the NPQ,ETR,EQY,qP increased with growth stage.6.The key techniques for super hybrid rice N-saving cultivationThe strategy for N-saving cultivation of SHSR in plain area:the key point was to have effective panicles and balanced grain number and weight.The optimum range of N application rate should be 135～180 kg/hm²,the ratio of N-P-K at 1:0.4 to 0.7:0.9 to 1.2,and the optimum transplanting density should be180,000 hills/hm².The key technique to achieve high yield of super hybrid rice under N-saving cultivation: high N-use efficient varieties,slow/controlled release N fertilizer,early transplanting for stronger seedlings,optimal planting densities,good water and fertilizer-management coupled with integrated pest control and anti-lodging techniques.更多还原