FLOODING STRESS: The Effects of Planting Pattern and Water Regime on Root Morphology,Physiology and Grain Yield of Rice

Field experiments were conducted over two growing seasons to investigate the effects of variations in water regime and planting pattern on the growth of rice plant roots and shoots and on yield. Four water regimes were evaluated with split plot design: intermittent flooding during the vegetative stage only (IF‐V); intermittent flooding extending into the reproductive stage (IF‐R); not flooded (NF); and continuously flooded (CF), interacting with three different planting patterns: single seedling per hill with wider 30 × 30 cm spacing (P1); single seedling per hill with closer 20 × 20 cm spacing (P2); and three to four seedlings per hill with 20 × 20 cm spacing (P3). The treatment combination CF/P3 corresponds most closely with current conventional practice. The other combinations were evaluated to contribute to a better understanding of the effects of the two parameters studied, respectively and together. IF‐V/P1 was considered as an approximation of System of Rice Intensification (SRI) practice. This study found that the combination of singly transplanted seedlings, both P1 and P2, with the IF‐V water regime improved root length density, root physiological activity, and chlorophyll content of the upper and lower leaves, leading to higher grain yield compared with the other treatment combinations. With continuous flooding (CF), P2 gave 23 % more yield compared with the P3 planting pattern. Combining IF‐V and P2 produced 32 % more grain yield compared with the CF/P3 treatment. These results showed a synergistic effect on grain yield from reduced intra‐hill competition and IF‐V water management. In these trials, there was no significant yield difference between the IF‐V/P1 and CF/P3 treatments. Wider spacing improved the performance of individual hills when grown under IF‐V water regimes, but tiller number per unit area remained a dominant determinant of yield. The yield reduction observed for CF/P1 compared with CF/P3 indicated that in more hypoxic CF soils, denser plant populations can produce more than sparser ones, whereas the latter benefit from more aerobic soil conditions. Intermittent irrigation during the vegetative growth stage and transplanting single seedlings/hill are major elements of SRI methodology. These findings contribute to an understanding of why SRI methods can produce the higher yields reported. A consideration of the effects of interaction between planting pattern and water regime shows the need to establish empirically the optimum values for these treatments according to varietal, soil and climatic characteristics for the greatest yield response.     

常规氮肥与缓释氮肥配施对不同株距机插杂交稻磷素吸收、转运及分配特征的影响

在前期研究确定总氮用量180 kg hm^–2下, 缓释氮肥与常规氮肥7∶3配施比例可获得机插稻高产的基础上, 研究缓释氮肥配施和不同株距下机插杂交稻磷素积累、分配与利用特征及其与产量的关系。采用二因素裂区设计, 设3种机插株距(行距均为30 cm) 16、18及20 cm和4个缓释氮肥用量(36、66、96和126 kg hm–2)与常规氮肥(均为54 kg hm^–2)配施处理。结果表明, 缓释氮肥用量对机插稻主要生育时期磷素积累量、各生育阶段磷素吸收量及吸收速率、结实期茎鞘磷素转运量及转运率和叶片磷素转运率及贡献率均有显著影响。在株距为18 cm, 群体密度为18.52万穴 hm^–2, 缓释氮肥(96 kg hm^–2)与常规氮肥(54 kg hm^–2)配施总量为150 kg hm–2时, 可有效提高机插稻对磷素的吸收, 促进结实期茎鞘、叶片磷素向穗部的转运及分配, 能充分发挥本区域机插杂交籼稻的优势, 产量可达11 463.8 kg hm–2, 为本试验的最佳肥密运筹处理。株距为16 cm, 群体密度(20.84万穴 hm^–2)相对较大, 施氮总量为180 kg hm^–2时, 群体吸收的磷总量较高, 进一步促进了植株体内磷素的吸收转运及分配, 有利于产量提高, 但从节本增效的角度考虑, 以缓释氮肥配施量150 kg hm^–2为宜; 株距增加到20 cm施氮总量在180 kg hm^–2下, 群体(16.67万穴 hm–2)较小, 吸收磷素的绝对量少, 茎鞘、叶片中的磷素向穗部转运量多, 穗部磷素积累量增加, 产量增加。相关分析表明, 株距与缓释氮肥配施量耦合下, 尤其以齐穗期至成熟期茎鞘磷素转运量与产量相关性较高(r = 0.72**), 更有利于产量的提高。     

水稻三角形强化栽培与正方形强化栽培、抛秧栽培、常规栽培的比较研究

为了探讨三角形强化栽培在生长发育及产量形成等方面的特点,找出最具增产潜力的栽培方式和技术,为其今后在水稻生产应用中提供实践依据。试验以‘D优527’为材料,研究了在不同施氮水平和密度下,水稻三角形强化栽培与正方形强化栽培、抛秧栽培、常规栽培水稻群体和个体关系、群体库源建成特征、水稻后期衰老及产量形成等方面的差异。结果显示：（1）三角形强化栽培和抛秧栽培在个体产量性状有所下降的情况下,依靠群体有效穗的提高达到高产目的,但适宜密度的三角形强化栽培显然要优于抛秧栽培;而正方形强化栽培则以强化个体生长发育为目标,在个体产量性状得到大幅提高的基础上,群体足够就能达到很好的增产效果,但增产效果不如三角形强化栽培。（2）适宜密度的三角形强化栽培、正方形强化栽培在生育后期能保持较高的LAI,抽穗期能积累更多的干物质,且其茎鞘物质向穗部的输出量、输出率及转换率均显著高于抛秧栽培和常规栽培,具有更高的产量潜力。（3）高肥处理（纯氮225 kg/hm2）比中肥处理（纯氮150 kg/hm2）产量增加6.36%,表明适当提高施氮水平,更有利于提高强化栽培产量。     

不同播种粒数对水稻生育及其产量的影响

选用龙粳9号品种,设计水稻三超栽培352孔大钵盘育苗1、2、3粒三个不同播种密度（粒数）及相应1、2、3个穴内不同苗数的宽行超稀植栽培处理,进行水稻超高产生育特点和产量构成因素的试验研究。结果表明：秧苗素质、成穗率、比叶重、剑叶叶绿素含量、灌浆速度等指标均呈随播种量的增加而减少的趋势,茎鞘叶干物质积累和分蘖态势都表现为1粒播种最佳;产量构成因素中每平方米穗数3粒＞2粒＞1粒,穗粒数1粒＞2粒＞3粒,结实率、千粒重随粒数增加呈下降趋势。表明定位定粒播种减少粒数是培育多蘖壮秧进行宽行超稀植栽培而大幅度提高水稻产量一个有效途径。     

优质稻核心种质青六矮1号及其衍生品种的性状相关性研究

对青六矮1号及其衍生品种(品系)的相关分析表明: 产量与有效穗数呈极显著正相关, 与每穗总粒数和每穗实粒数呈显著负相关; 倒三叶长与倒二叶长呈极显著正相关, 与着粒密度呈显著负相关, 与粒长呈显著正相关, 与垩白率呈显著负相关, 与垩白度呈极显著负相关, 与胶稠度呈显著正相关, 与直链淀粉含量呈显著负相关. 主成分分析表     

钵苗机插密度对不同穗型水稻品种产量、株型和抗倒伏能力的影响

选用3种穗型水稻品种,设置3种钵苗机插密度,以毯苗机插为对照(CK),系统研究钵苗机插不同密度对水稻产量及其构成、穗部性状、冠层叶系配置、茎秆物理特性和抗倒伏的影响,旨在探明水稻钵苗机插配套不同穗型品种适宜栽插规格及其增产特点;同时,阐明钵苗机插不同密度下水稻株型特征和抗倒伏特性。结果表明:(1)3种钵苗机插密度处理下,大穗型品种产量随密度降低呈先增后降的变化趋势,但均显著高于CK;中、小穗型品种产量有随着密度降低而下降的趋势。不同穗型品种穗数随着密度降低而显著减少,每穗粒数显著增加,结实率和千粒重无明显变化规律。(2)钵苗机插下不同穗型水稻品种的穗长、着粒密度、单穗重、一次枝梗数、二次枝梗数、一次枝梗粒数和二次枝梗粒数均随密度降低而增加,且高于CK;一、二次枝梗数比值和一、二次枝梗粒数比值随密度降低而呈下降趋势。(3)钵苗机插下不同穗型水稻品种的上三叶的叶长、叶宽、叶基角、披垂度和比叶重随着密度降低而呈增加趋势;且上三叶的叶长、叶宽和比叶重高于CK。(4)随着密度降低,不同穗型品种钵苗机插水稻基部N1、N2、N3节间长度减少,茎秆粗度、茎壁厚度和节间干重增加,穗下节间长、秆长、株高、重心高增加,而相对重心高有减小趋势。(5)不同穗型品种钵苗机插水稻基部节间N1、N2、N3抗折力和弯曲力矩随着密度降低而增加,倒伏指数呈下降趋势,且低于CK。说明水稻钵苗机插配套大穗型品种宜适当降低密度,增加每穗粒数以获高产;中穗型品种需兼顾穗数和每穗粒数,提高群体颖花量而增产;小穗型品种依靠穗数而提高产量。水稻钵苗机插降低密度能改善穗部性状和增加上三叶的叶面积,但增大了叶基角和披垂度,同时利于缩短基部节间长度,增加基部节间粗度、茎壁厚度和充实度,从而提高抗折力,降低倒伏指数。     

重穗型水稻植株抗倒伏能力的研究

以18个不同穗重型水稻品种为材料，研究了重穗型水稻植株的抗倒伏能力及其与茎秆的物理性状、机械组织特性的关系。结果表明：重穗型品种单穗重大、产量高与其株高的适当增加密切相关。重穗型品种由于单穗重和株高的增加，弯曲力矩加大，但抗折力也明显提高，故而其茎秆抗倒伏能力并未降低。重穗型品种茎秆抗折力强的主要原因     

水稻机插缺丛条件下自然补偿能力研究

为了提高机插水稻的产量和经济效益,通过田间模拟缺丛试验,研究缺丛对产量造成的影响及其自然补偿能力。结果表明,在缺丛率为0%(CK)、5%、10%、15%、20%五个处理中,水稻产量随着缺丛率增加而下降,减产幅度为2.5%~6.3%,缺丛率达10%以上,减产达显著水平。缺丛四周植株分蘖增强,而成穗率下降不太明显,有效穗数增加,单丛产量增加,从而对缺丛起到补偿作用,补偿作用随着缺丛率提高而增强。但仍不能完全弥补因缺丛所带来的穗数损失,导致减产。同时每穗总粒和实粒数、千粒重也随着缺丛率提高而相应有所降低。因此,机插水稻缺丛在所难免,缺丛率要控制在5%以下,当缺丛率达到10%以上时,应适当进行人工补缺,达到增产增效的目的。     

机械化种植对杂交籼稻F优498产量构成与株型特征的影响

为探明机械化种植杂交籼稻高产群体的株型特征, 以F优498为材料, 采用二因素裂区设计, 研究了不同穴苗数与播期下机直播、机插、手插3种种植方式的株型特征及其与产量构成的关系。结果表明: (1) 不同种植方式株型特征差异显著, 机直播和机插上三叶叶长、叶宽和叶间距大, 但叶基角和披垂度也较大; 手插上三叶大小适宜, 叶片厚而挺直; 机直播和机插株高和着生高度显著大于手插, 但手插比叶重、单株穗数和总叶片数显著高于机械化种植; 机直播的茎蘖夹角、穗粒数和单穗重显著低于机插和手插。推迟播期和低苗处理均使叶片增大, 比叶重、粒叶比、单株穗数、穗粒数和结实率随播期延迟显著降低。单穗重与上三叶长度、宽度、着生高度和株高均呈显著或极显著正相关, 以机插最高, 手插次之, 机直播最低。(2) 机直播产量显著低于机插和手插, 且随播期延迟和穴苗数减少显著降低。产量及其构成与株型特征密切相关, 机械化种植杂交籼稻高产株型的显著特征为适宜的株高、上三叶长度、群体LAI和茎集散度; 叶宽、比叶重、叶间距大和直立性好。足穗和大穗的统一是实现水稻高产的关键, 塑造个体优良的株型与优化群体结构是增产的前提, 机械化种植杂交籼稻应在时间允许的条件下尽早播栽, 穴苗数以3苗左右为宜。     

不同种植规格对杂交水稻江优919生长及产量的影响

为确定杂交水稻江优919的适宜手插密度,采用两因子随机区组设计,在天柱县和石阡县开展了不同种植规格试验研究。结果表明：密度与有效穗数、穗实粒数等产量构成因子密切相关;同一密度、相同株距、不同的宽窄行设置对产量形成有一定影响;天柱点适宜手插密度为13468～14815穴／667m2,株距在15～16．5cm之间,30cm等行距种植;石阡点适宜手插密度为10870穴／667m2,株距为23．1cm,行距设置为36．6＋16．5cm或33．3＋19．8cm,平均为26．55cm。     

Making an Indian traditional rice variety Mahsuri, bacterial blight resistant using marker-assisted selection

Mahsuri a popular traditional variety and the first rain-fed mega variety of the Indian sub- continent. It is highly susceptible to bacterial leaf blight caused by Xanthomonas oryzae pv.oryzae. Nine best performing families of Mahsuri pyramid containing four bacterial blight resistance genes (Xa4, xa5, xa13 and Xa21) were evaluated for agronomic, yield and its related characters viz. days to 50% flowering, plant height, number of tillers, panicle length, filled grains per panicle, grain weight, and yield under natural and disease pressure conditions for three consecutive wet seasons. In addition these pyramids were also evaluated for three different spacings to find out the optimum spacing under disease free and disease pressure conditions. Results revealed that under disease free conditions there was no significant difference between the pyramids and the parent for the characters evaluated in each spacing. However characters plant height, number of tillers, panicle length, filled grains per panicle, yield per plant and yield per sq. m. showed significant variation between the different spacings across seasons. Under heavy disease pressure the parent exhibited highly susceptible reaction whereas the pyramid families were highly resistant. A wider spacing had less yield loss when compared to dense planting under BB infestation in case of parent. There was no such yield loss in the pyramid families. When yield per sq. m. was taken into consideration the 20 × 20 cm spacing showed the highest yield when compared to the other two spacings since number of plants were more. The pyramids insulated the yield loss against bacterial leaf blight and are a gain to the farmers to help overcome the heavy yield losses due to this disease. These pyramids have the potential to replace the parent and can be used directly. In addition they can be used as donors for bacterial blight resistance in any breeding program.     

The utility of hill plots in oat research

From 1955 through 1963, approximately 300,000 hill plots have been used in various experiments in the Iowa small grain research program. When grain yield, plant height, and heading date were measured on the same varieties, the genetic correlations between rod rows and hills were 0.98, 0.96 and 0.96, respectively.The coefficients of variation for plant height, weight per volume, spikelets per panicle, panicles per plant, weight per 100 seeds were similar for rod rows and hills. However, the coefficients of variability for grain yield ranged from 2 to 5 times larger for hills than for rod rows. Competition between varieties in adjacent hills had little effect on the performance of varieties.The best method for planting hill plots is the conventional method opening a hole in the soil about 2 inches deep with a hoe, pouring the seed in the hole, and covering it with soil. Rates of planting influenced the expression of grain yield, panicles per plant, and spikelets per panicle, but not weight per 100 seeds and plant height. Approximately 30 seeds per hill appeared the most desirable planting rate.Journal Paper No. J-5064 of the Iowa Agricultural and Home Economics Experiment Station, Ames, Iowa. Project No. 1176. Received for publication Febr. 23, 1965. In cooperation with the Crops Research Division, Agricultural Research Service, U. S. Department of Agriculture.Professor of farm crops.     

Physiological Analysis of Growth, Yield Development and Grain Quality of Some Deep-water Rice (Oryza sativa L.) Cultivars

A field experiment was conducted with 10 deep‐water rice varieties (nine traditional and one improved), viz. Amona, Maguri, Rangoli, Kakua, Panikakua, Deoribao, Moimonsingia, Duatkalam, Dalbao and PJNB‐96‐10, to study their physiological performance, grain‐quality characters and yield. Among the cultivars, significant variations were recorded in plant height, root length, number of internode, tiller number, number of ear‐bearing tillers, panicle length, panicle weight, number of spikelets per panicle and filled grain percentage. The highest number of spikelets per panicle (199), filled grain percentage (95 %) and grain yield (4.32 t ha^?1) were recorded in Maguribao. The highest grain length was recorded in PNJB‐96‐10 (9.5 mm), whereas highest grain thickness was observed in Duatkalam (2.8 mm). Glutelin was the most dominant fraction of protein in all the tested cultivars. Maguribao showed the highest glutelin content (26.7 mg g^?1 dry weight), whereas Panikakua showed the highest amylose (24.45 %) and crude fat (4.64 %) content. Differences were also recorded among cultivars in fibre, ash and iron content in grain. Maguribao was found to have superior physiological traits for growth and hence may be considered for inclusion in deep‐water rice breeding programmes.     

土壤水分胁迫对水稻产量和品质的影响

以农大3号为试材,盆栽,控水,研究了不同生育阶段土壤水分（水势）胁迫（≤－75 kPa）对水稻产量和品质的影响。结果表明,孕穗中期土壤水分胁迫导致功能叶变短,穗粒数减少,生物产量与经济产量降低,糙米率、米粒长宽比、食味下降。分蘖期干旱胁迫使单穴有效穗数降低,生物产量与经济产量下降。出穗后干旱胁迫导致叶片萎蔫变黄,叶面积指数下降。乳熟期和灌浆期干旱胁迫,饱满粒率、饱满千粒重降低,整精米率下降。灌浆期干旱还导致垩白率、垩白度明显增高。蜡熟期干旱使叶绿素含量减少,胶稠度、蛋白质含量降低。     

江淮稻区不同穗型粳稻品种主要农艺和品质特性的比较分析

依据着粒密度，对江淮稻区大面积生产应用的和新近育成的36个粳稻品种(系)进行聚类分析。结果表明，供试品种可分成半密穗型(Ⅰ)、偏密穗型(Ⅱ)和密穗型（Ⅲ）三类。随着水稻品种由散穗型向半密穗型、偏密穗型和密穗型的演变，产量性状、品质性状、形态性状和部分生理、生化性状发生了明显的变化，产量、每穗总粒数和实粒数显著增加，而穗数/m²、千粒重和结实率呈下降趋势；株高增加，上部三张叶片变长、变宽，生物日产量增高；穗部一、二次枝梗数增多，着粒密度变大；抽穗期和成熟期叶片、茎秆的含氮量和叶片叶绿素含量增高；糙米率和整精米率下降、垩白粒率降低、胶稠度变硬、蛋白质含量呈上升的趋势。     

植物生长调节剂对寒地水稻产量和品质的影响

为了研究不同植物生长调节剂对寒地水稻产量和品质的影响,在大田条件下,以寒地水稻‘空育131’为材料,叶面喷施4种植物生长调节剂,调查叶龄及茎蘖动态变化,研究水稻抽穗后物质生产、转运和输出变化,比较农艺性状、产量构成、产量及品质变化的差异。结果表明：与CK相比,叶面喷施ND调节剂明显加速了水稻叶龄进程,增加了水稻分蘖茎数、穗长以及抽穗至乳熟阶段水稻茎鞘物质的输出率和转运率,显著提高了水稻抽穗期的光合势和净同化率,提高了水稻籽粒千粒重、穗粒数以及单株产量,进而提高了水稻产量,实现产量增幅7.04%,BaDao调节剂次之;另一方面,叶面喷施ND和BaDao提高了稻谷糙米率和精米率,以ND表现最佳。而喷施PY显著降低植株高度和节间长度,抑制了水稻株高和节间长度的正常生长,明显降低了稻米的垩白率、垩白大小和垩白度,其次是BaDao调节剂。以上试验研究表明,叶面喷施ND和BaDao调节剂,可提高寒地水稻籽粒产量,改善稻米品质。     

东北地区水稻主要株型性状比较分析

以2006年和2007年辽宁、吉林、黑龙江3省水稻区域试验品种(系)为材料,分别在辽宁沈阳、吉林公主岭和黑龙江五常研究了水稻的株型特征及其与产量的关系。结果表明东北地区多数品种是穗型直到半直立(82.6%)、着粒密度中到稀(80.2%)、穗重轻到中(72.8%)、二次枝梗分布下部优势型(98.8%)。黑龙江主要是弯、半直立穗型品种,吉林以半直立穗型品种为主,辽宁则以直立穗型品种为主。吉林和黑龙江品种多数是中、稀穗型和中、轻穗型,辽宁主要是中、密穗型和中、重穗型。穗颈大、小维管束数和第2节间大、小维管束数平均值表现为辽宁＞吉林＞黑龙江。辽宁上三叶长、宽大于吉林和黑龙江,但叶基角较小。穗颈大、小维管束数和第2节间大、小维管束数与一、二次枝梗数和一、二次枝梗粒数及二次枝梗粒率呈极显著正相关,与一、二次枝梗结实率和千粒重呈负相关。聚类分析结果表明,东北地区育种单位选育的品种多数处于中、高产量水平,总体上有穗型直立、着粒密度大、重穗型、穗颈维管束数多、上三叶长且宽而角度小、株高和生物产量高有利于高产的趋势。     

杂交水稻籽粒比重与产量品质性状相关分析及其在育种中的应用

为了探究杂交水稻籽粒的比重与产量因素及品质因素相关性,以高产优质品种天优华占为对照,对7个三系不育系与5个自选恢复系进行杂交配组后得到组合的单株穗数、每穗总粒数、籽粒体积、比重、充实度、千粒重等进行研究。结果发现,千粒重是影响产量的最大因素,其次是单株穗数；籽粒比重的提高可以提高整精米率和降低垩白度,从而改善水稻的产量和品质。研究认为,杂交稻水稻的选育中,籽粒较大的情况下兼顾单株穗数和充实度,且单方面强调通过增加粒重去提高产量会导致整精米率降低,因此为兼顾产量与品质,籽粒比重适中为宜。     

Using GGE Biplot Analysis to Evaluate Interrelationships between Yield and Yield Components of Oat Genotypes in Different Growing Seasons

The aim of this study was to evaluate oat genotypes for grain yield and yield components in both 2014-2015 and 2015-2016 growing seasons using GGE biplot analysis. Experiments were laid out according to lattice design. Biomass at harvest, grain yield, number of grain per panicle, weight of grain per panicle, flag leaf width, flag leaf height, plant height, stem diameter, thousand kernel weight, time of panicle emergence, harvest index, panicle length, and spikelet per panicle were evaluated for 56 oat genotypes. GGE biplot graphics of the first and second years explained 54.4 and 55% of total variation, respectively. Grain yield, number of grains per panicle, and weight of grain per panicle were closely and positively associated in both growing seasons. Recently registered cultivar Sari and lines 26, 29, and 30 were found as promising genotypes for Çanakkale conditions. Traits of genotype at different growing seasons can be visually studied using different genotype-by-trait (GT) biplots.     

贵州省不同年代糯高粱品种（系）农艺性状演变分析

以贵州省不同年代酿酒用糯高粱品种（系）为研究对象,采用随机区组试验设计,对其农艺性状、产量构成以及抗性差异进行分析,结果表明：随着年代更替,贵州省酿酒用糯高粱单产逐步提高。新品种（红缨子、黔高8号）较老品系（黑壳糯、红壳糯）平均单产增幅25%以上;穗粒数、穗粒重增加显著,增幅分别为51.7%、62.7%;主穗一、二级枝梗数增加幅度分别为19.8%、62.7%;株高降低24.9%,茎粗增加9.5%;节间数增加0.9个,节间长缩短13.3cm;单株叶面积和叶面积指数增加显著;倒伏率、发病率下降显著,成穗率明显提升。各指标相关性分析显示,产量与穗粒数、穗粒重,穗粒数与主穗一、二级枝梗数呈极显著正相关;产量与株高、倒伏率极显著负相关,与茎粗正相关,相关系数分别为-0.981、-0.970和0.928,株高、茎粗与倒伏率相关显著,相关系数分别为0.964和-0.910;产量与叶面积指数正相关,与发病率显著负相关。总的结果表明,主穗一、二级枝梗数的增加提高了糯高粱的穗粒数,植株株高的降低、茎粗的增加促进了抗倒性的提升,抗病性的提升保证了后期叶片光合作用的持续进行,最终提高了糯高粱产量。