Tobacco-rice rotation is a common farming system in south China, and many tillage practices such as straw mulching, dolomite dust, and quicklime application have been adopted to improve crop production. These agricultural management practices alter soil physical and chemical properties and affect microbial life environment and community composition. In this research, six tillage practices including no tobacco and rice straw mulching (CK), tobacco and rice straw mulching (TrSr), rice straw returning fire (TrSc), tobacco and rice straw mulching with dolomite dust (TSD), rice straw returning fire and quicklime (TSQ), and rice straw returning fire, quicklime and reduced fertilizer (TSQf) were conducted to detect changes in soil bacterial diversity and composition using Illumina sequencing. The results showed that the total number of operational taxonomic units (OTUs) from the six treatments was 2030, and the number of mutual OTUs among all samples was 550. The TrSc treatment had the highest diversity and richness, while TSQf had the lowest. Soil physio-chemical properties and microbial diversity can influence each other. Proteobacteria and Actinobacteria had the greatest proportion in all treatments. The abundance of Nitrospirae was the highest in the TrSc treatment. The TSQf treatment had the highest abundance of Firmicutes. The abundance of Nitrospira in the TrSc treatment was 2.29-fold over CK. Streptomyces affiliated with Firmicutes improved by 37.33% in TSQf compared to TSQ. TSQf treatment was considered to be the most important factor in determining the relative abundance at the genus level.

为明确精准条播(precision drill sowing, PS)在连作晚稻长秧龄机插中的有益效果。本试验以甬优1540为供试品种, 设置标准9寸秧盘横向16条(PS-16, 45.7 g 盘^-1)和18条(PS-18, 60.5 g 盘^-1)精准条播, 并以传统撒播(broadcast sowing, BS, 60.5 g 盘^-1)作为对照, 同期播种, 设置20、25、30和35 d 4个机插秧龄, 比较分析各播种方式水稻秧苗素质、机插特性、群体生长及产量形成的变化。结果表明: (1) 精准条播提高秧苗群体透光性, 与撒播相比, 精准条播提高了长秧龄秧苗的素质, 增加了带分蘖秧苗的比例, 其中PS-16秧苗素质最好, 带分蘖秧苗的比例最高。(2) 与撒播相比, 精准条播显著降低机插漏秧率, 提高机插取秧2~3株苗比例, PS-16和PS-18间差异不明显。秧龄延长增加机插秧苗伤根程度和伤苗率, 降低秧苗存活率, 其中PS-16的伤根程度和伤苗率增加幅度最小, 机插秧苗存活率最高。(3) 机插秧龄延长增加了秧苗缓苗返青天数进而推迟水稻生育期, 各机插秧龄下, PS-16的缓苗返青期最短, 生育期因秧龄延长而推迟的天数最少。(4) 精准条播有效促进分蘖, 其中PS-16效果最好, PS-16机插10 d分蘖数平均比PS-18和BS高16.4%和20.8%。机插秧龄延长降低群体分蘖高峰苗数, 各秧龄下高峰苗数PS-16>PS-18>BS。成穗率在不同播种方式处理间差异不大。(5) 秧龄延长降低抽穗期叶面积指数和干物质积累, PS-16下降幅度最小。(6) 不同机插秧龄下, 精准条播通过增加有效穗数进而提高水稻产量, 有效降低了机插秧龄延长导致的产量损失, 各机插秧龄下产量PS-16>PS-18>BS。试验说明, 与传统撒播相比, 精准条播增强了秧苗素质, 提高了机插质量, 缩短了长秧龄下的返青时间, 促进了分蘖早发, 增加了叶面积指数和干物质积累, 进而有效减少了连作杂交晚稻因机插秧龄延长而引起的产量损失, 其中精准16条条播效果好于18条条播。

【目的】探究不同秧龄下机插方式与密度对杂交稻光合生产及产量的影响,为水稻机插秧配套技术的应用提供理论和实践依据,【方法】以超级杂交稻F优498为材料,采用两因素裂区试验设计,在25 d和40 d秧龄下,设置“钵苗机插+高密度(M₁D₁)”、“钵苗机插+中密度(M₁D₂)”、“钵苗机插+低密度(M₁D₃)”、“毯苗机插+高密度(M₂D₄)”、“毯苗机插+中密度(M₂D₅)”、“毯苗机插+低密度(M₂D₆)”6种机插方式与密度的处理开展试验。【结果】秧龄与插秧方式和密度对水稻主要生育期光合生产及最终产量均存在显著的调控作用,且互作效应显著。同一机插方式及密度处理下,机插25 d秧龄水稻的秧苗素质、群体茎蘖数、叶面积指数(LAI)、单茎叶片和茎鞘表观转运量及转运率、单茎和群体干物质量、阶段干物质积累量、群体生长率、光合势、抽穗后净同化率以及产量均明显优于40 d秧龄处理。同一秧龄和机插方式下,水稻群体茎蘖数、各时期LAI和衰减率、群体干物质量、光合势以及抽穗前干物质积累量、群体生长率、净同化率均表现出随密度的增加而增加的趋势;而抽穗后物质积累量、群体生长率、净同化率在25 d秧龄下钵苗机插均表现为随着密度的增加呈现先增加后降低的趋势,以M₁D₂处理最优,而毯苗机插则表现为随着密度的降低而降低的趋势,且钵苗机插各指标较毯苗优势明显。25 d秧龄下,钵苗机插行距33 cm、配套株距14.5~15.5 cm,因群体总颖花数、结实率的优势,产量显著高于其余处理,其中又以行距33 cm、株距15.5 cm最能充分发挥其杂交籼稻株型的优势,提高光合物质生产,产量最高可达到12.74 t/hm²,是本研究最佳组合;而毯苗机插随秧龄增大以及栽插密度的降低,群体质量指标恶化,有效穗数不同程度降低,产量并不高。

【目的】 机插秧是当前我国水稻种植发展的主要方向,探索不同秧龄下机插方式与密度对杂交稻根系生长及氮素利用特征的影响,对提高水稻产量和氮肥利用率,加快水稻机械化高产高效栽培技术的集成具有重要意义。【方法】 以超级杂交稻F优498为材料,采用两因素裂区试验设计,在25 d和40 d秧龄下,通过“钵苗机插+高密度”、“钵苗机插+中密度”、“钵苗机插+低密度”、“毯苗机插+高密度”、“毯苗机插+中密度”、“毯苗机插+低密度”6种机插方式与密度配合的处理,研究其对氮素利用特征、根系生长特性的影响,并探讨根系生长与氮素利用及产量的关系。【结果】 各生育时期氮素吸收与各阶段氮素积累量,齐穗至成熟期氮素吸收速率、茎和叶的氮素转运量、穗部氮素增加量、氮素偏生产力、拔节后根系干质量以及产量,25 d秧龄均较40 d秧龄优势明显。在相同秧龄下,与毯苗机插相比,钵苗机插可促进杂交稻各生育时期根系生长,提高氮素积累及吸收速率,增加结实期各器官氮素的转运量,从而提高稻谷产量;尤其在秧龄25 d、钵苗机插株距为15.5 cm时,较其他处理优势明显,为本研究最优处理。毯苗机插在25 d秧龄与株距为12 cm时,也能够获得较高产量;密度降低,提高了根冠比及茎叶转运率,但降低了各时期的氮素积累量、吸收速率以及结实期茎叶的转运量,产量较低。相关性分析表明,不同秧龄机插方式与密度配合下,主要生育时期根干质量与产量及氮素吸收利用均存在极显著正相关( r = 0.47**~ 0.83**),齐穗和成熟期根冠比与产量及氮素吸收利用均极显著负相关( r = -0.52**和-0.79**)。【结论】 机插杂交稻25 d秧龄根系生长及氮素利用特性均优于40 d秧龄,且钵苗较毯苗机插能优化水稻个体与群体关系,但其机插密度不宜过高或过低,行距与株距以33 cm×15.5 cm为宜,可促进氮素吸收利用及产量同步提高;且拔节与成熟期根系的生长对产量影响显著。研究结果可为水稻钵苗机插秧高产高效栽培技术集成及应用提供技术和实践依据。

适宜的播种量与秧龄搭配是保障水稻丰产优质的前提。以籼粳杂交稻甬优6711为供试品种，采用两因素（播种量、秧龄）裂区设计，以探明不同秧龄和播种量处理（T1，秧龄20 d、播种量50 g/盘；T2，秧龄20 d、播种量70 g/盘；T3，秧龄30 d、播种量50 g/盘；T4，秧龄30 d、播种量70 g/盘）对机插稻秧苗素质、产量和加工品质的影响。结果表明，T2和T3处理的产量较高，较T1处理分别增产24.7%和25.2%，较T4处理分别增产17.4%和17.8%。与20 d秧龄处理相比，30 d秧龄处理显著增加苗高、茎基宽、百苗地上及地下部干物质量；70 g/盘播种量处理较50 g/盘播种量处理显著降低苗高、茎基宽和发根力。整体而言，T3处理的秧苗素质最好。从稻米加工品质来看，与20 d秧龄处理相比，30 d秧龄处理的精米率和整精米率均显著下降，但糙米率差异不显著；与50 g/盘播种量处理相比，70 g/盘播种量处理能显著提高糙米率和精米率，但对整精米率影响小。综合来看，T2处理的稻米加工品质最优，而T3处理降低了稻米加工品质。因此，在苏北杂交中粳稻种植区，选择短秧龄、高播量搭配（T2）能同时获得丰产优质，长秧龄、低播量搭配（T3）能获得丰产，但稻米加工品质显著下降。

【目的】探索印度梨形孢(Piriformospora indica)在水稻生产中的使用方式及应用效果。【方法】以泰优203和ZY246籼稻品种为研究材料，以1 g/L的印度梨形孢菌液为基准施用量，运用灰色关联度分析方法，综合评估了印度梨形孢、复合肥及其组合施用三种处理方式对水稻机插秧秧苗素质的影响。【结果】复合肥不会影响印度梨形孢在水稻根部的正常定殖，可以将印度梨形孢与复合肥组合施用；两者的组合施用不仅能显著促进秧苗生长，提高秧苗生物量、叶绿素含量、根系活力和硝酸还原酶活性，还能促进生长相关基因的表达。【结论】本研究不仅深化了对印度梨形孢促进水稻生长机制的理解，而且为印度梨形孢在水稻生产中的实际应用，尤其是机插秧育秧环节，提供了理论依据和实践指导。

Drought is common under rainfed lowlands in Lao People’s Democratic Republic, and with the uncertain onset of rains during the wet season, delay in transplanting results in yield reduction. This study aims to explore ways to ameliorate the negative influence of delayed transplanting on rice crop. A field experiment was conducted for two wet seasons to investigate the effect of seedling age and seedling density on crop performance in terms of grain yield and water productivity. The experiment was laid out in a split–split plot design in four replicates, with seedling age as the main plot, seedling density as the subplot, and varieties as the sub-sub plot. In both years, there were significant seedling age and variety interactions on grain yield. Higher grain yields were observed with older seedlings having stronger tillering propensity. Seedling density did not affect grain yields in both years, but on grain yield components. Shorter duration variety received less supplemental irrigation than longer duration varieties. Late transplanting improved total water productivity but decreased irrigation water productivity due to harvesting delay. The total crop growth duration (from sowing to maturity) was prolonged with transplanting delay. However, the total stay of plants in the main field (from transplanting to maturity) was reduced by 3–5 d for every 10 d delay in transplanting. The results indicated that a good selection of varieties and increasing seedling density improve crop performance and water productivity with delayed transplanting.

【目的】明确不同类型双季晚粳稻在长江中下游不同生态区产量表现、生育期及温光资源配置差异,为早籼-晚粳模式在长江中下游稻区应用提供理论依据。【方法】试验于2018–2019年在浙江富阳(30.13°N,海拔41.7 m)和温州(28.52°N,海拔83 m)开展。选择生产上大面积应用品种,以高产籼稻(IR)为对照,设置常规粳稻(IJR)和籼粳杂交稻(IJHR)2个处理。比较不同生态区晚季温光条件下籼稻、常规粳稻和籼粳杂交稻在产量、生育特性以及温光资源配置上的差异。【结果】1)低纬度下粳型水稻品种干物质量、有效穗数及库容较高纬度均有所下降,导致产量降低2.4%~19.1%;但结实率和千粒重稳定或略有提高。同时,籼粳杂交稻产量在两地均最高,分别为8.8~10.3 t/hm²(富阳)和8.0~10.2 t/hm²(温州);2)供试品种生育时期因纬度不同而存在差异。与高纬度相比,低纬度的水稻营养生长期无显著差异,穗发育期有所缩短(4.2%~27.3%),而灌浆期显著缩短,其中籼稻、常规粳稻以及籼粳杂交稻分别缩短7.3%~11.9%、20.8%~41.9%以及23.1%~35%。3)不同生育阶段温光配置差异主要体现在灌浆期,平均温度低纬度要高于高纬度(籼稻提高0.4~2.4 ℃;常规粳稻2.3~3.5 ℃;籼粳杂交稻2.5~2.8 ℃);有效积温纬度间的差异随品种类型而异,其中籼稻无显著变化,常规粳稻和籼粳杂交稻分别降低24.7~126.4 ℃和25.7~107 ℃。4)主成分分析表明,纬度变化造成的温光资源积累差异(PC1和PC2)是主因(贡献度49%),也是产量差异的主要原因;其次为品种的温光敏感性(PC5,贡献度18%)以及品种的穗粒结构(PC3,贡献度14%)。【结论】与高纬相比,低纬粳型水稻产量降低主要源于生育期缩短(灌浆期为主),有效积温减少,库容降低。籼粳杂交稻在低纬度仍具有较高的产量优势,可能源于其较强的穗粒优势。有鉴于此,重(大)穗型粳稻在长江中下游较低纬度双季晚稻种植可能更具有应用潜力。

Global warming would deteriorate rice (Oryza sativa L.) quality, especially chalk characteristic. To better cope with the challenges from global warming, the effects of nitrogen (N) fertilizer at heading stage on rice quality under elevated temperature during grain‐filling stage were investigated. Four different growth regimes, including no warming without N fertilizer at heading stage (CK), elevated temperature without N fertilizer at heading stage (ET), elevated temperature with N fertilizer at heading stage (ET+N), no warming with N fertilizer at heading stage (CK+N), were conducted. Elevated temperature during grain filling was achieved by a free‐air temperature enhancement facility with the increase of 4°C in ET and 3.7°C in ET+N. Results showed that elevated temperature decreased rice appearance quality and cooking quality and increased rice nutritional quality and eating quality. Grain‐filling rate and amyloplast development for both superior and inferior spikelets were obviously accelerated during early grain‐filling stage by elevated temperature. The application of N fertilizer at heading stage could inhibit the deterioration of rice quality, particularly for chalk performance, and may be associated with the alleviation of grain‐filling rate and amyloplast development. The above evidence indicated that the application of N fertilizer at heading stage is efficient to mitigate rice quality deterioration under higher temperatures in the Yangtze River Valley.