Plant Ideotype at Heading for Super High-Yielding Rice in Double-Cropping System in South China

The newly released super high-yielding hybrid rice combinations, Yueza 122, Fengyou 428, Peiza 67, and the super high-yielding conventional cultivars, Guangchao 3 and Shengtai 1, were grown in both early and late seasons. The morphological characters of each population were investigated at the heading stage, and the data were analyzed by using ANOVY and other statistic methods. The plant ideal morphological characters at the heading stage were established as follows： 1 ） for the early-season cropping, 90-105 cm plant height; 11-12 tillers per plant; 35-40 em length and 2.1-2.2 cm width of flag leaf; 46-50 cm length and 1.8-2.1 cm width of the second leaf from the top （L2）; 59-64 cm length and 1.4-1.9 cm width of the third leaf from the top （L3）; 7°-14°, 18° and 200-33° for the ideal leaf angles of the flag leaf, L2 and L3, respectively; 2） for the late-season cropping, 90-100 cm plant height; 9-15 tillers per plant; 30-41 cm length and 1.8-2.0 cm width of flag leaf; 53-61 cm length and 1.3-1.8 cm width of L2; 52-58 cm length and 1.2-1.5 cm width of L3; 9°-19°, 15°-37° and 16°-49° for the ideal leaf angles of the flag leaf, L2 and L3, respectively. The main physiological characteristics of these varieties were also analyzed.

Inter-provincial Differences in Rice Multi-cropping Changes in Main Double-cropping Rice Area in China: Evidence from Provinces and Households

Since the early 1980 s, the multi-cropping index for rice has decreased significantly in main double-cropping rice area in China, which is the primary double-cropping rice(DCR) production area. This decline may bring challenges to food security in China because rice is the staple food for more than 60% of the Chinese population. It has been generally recognized that rapidly rising labor costs due to economic growth and urbanization in China is the key driving force of the ‘double-to-single' rice cropping system adaption. However, not all provinces have shown a dramatic decline in DCR area, and labor costs alone cannot explain this difference. To elucidate the reasons for these inter-provincial distinctions and the dynamics of rice cropping system adaption, we evaluated the influencing factors using provincial panel data from 1980 to 2015. We also used household survey data for empirical analysis to explore the mechanisms driving differences in rice multi-cropping changes. Our results indicated that the eight provinces in the study can be divided into three spatial groups based on the extent of DCR area decline, the rapidly-declining marginal, core, and stable zones. Increasing labor cost due to rapid urbanization was the key driving force of rice cropping system adaption, but the land use dynamic vary hugely among different provinces. These differences between zones were due to the interaction between labor price and accumulated temperature conditions. Therefore, increasing labor costs had the greatest impact in Zhejiang, Anhui, and Hubei, where the accumulated temperature is relatively low and rice multi-cropping index declined dramaticly. However, labor costs had little impact in Guangdong and Guangxi. Differences in accumulated temperature conditions resulted in spatially different labor demands and pressure on households during the busy season. As a result, there have been different profits and rice multi-cropping changes between provinces and zones. Because of these spatial differences, regionally appropriate policies that provide appropriate subsidies for early rice in rapidly-declining marginal zone such as Zhejiang and Hubei should be implemented. In addition, agricultural mechanization and the number of agricultural workers have facilitated double-cropping; therefore, small machinery and agricultural infrastructure construction should be further supported.

Effects of different mechanical direct seeding methods on grain yield and lodging resistance of early indica rice in South China

Direct seeding of rice has become a main planting method due to the low labor input and high economic benefit in South China.Dry direct seeding(DDS)has been widely used for single-season rice planting establishment.However,few studies have examined the performance of early-season indica rice under mechanical dry direct seeding.A two-year field experiment was conducted with two indica rice cultivars(i.e.,Zhongjiazao 17 and Zhuliangyou 819)to study lodging characteristics and grain yield formation under DDS,flooded direct seeding(FDS)and wet direct seeding(WDS)patterns.The results showed that the annual grain yield in DDS was higher by 14.42–26.34%for cultivar ZLY819 and 6.64–24.58%for cultivar ZJZ17 than in WDS and FDS,respectively,and these increases were mainly attributed to the improvement of the panicles.The DDS pattern significantly increased the seedling emergence rate of early indica rice cultivars,and increased total dry weight and crop growth rate.Meanwhile,shorter basal internodes,better stem diameter and stem wall thickness and lower lodging index were found in DDS in contrast to FDS and WDS.In particular,DDS improved the stem lodging resistance.Our results suggested that the appropriate direct seeding method was beneficial for improving the grain yield and lodging resistance of early indica rice.

Studies on the Morphological Characters of South China Double Cropping Super Rice at the Active Tillering Stage

The morphological characters of the newly released super hybrid rice in South China, Yueza 122, Fengyou 428, Peiza 67, and super conventional varieties, Guangchao 3, Shengtai 1 at the active tillering stage in both early and late crops were investigated. Using the analysis of variance and other statistic methods, the ideal morphological characteristics of South China double cropping super-rice at the active tillering stage were determined. They are 55-60 cm in the early crop and 60-76 cm in the late crop for the ideal plant height, about 15 tillers in the early crop and 14-19 tillers in the late crop for the ideal tiller number per plant, 40-44 cm in the early crop and 42-60 cm in the late crop for the ideal length of the first leaf under the top leaf, 1.2-1.4 cm in the early crop and 1.2-1.3cm in the late crop for the ideal width of the first leaf under the top leaf, 39- 44 cm in the early crop and 37-43 cm in the late crop for the ideal length of the second leaf under the top leaf, 1.1-1.4 cm in the early crop and about 1.1 cm in the late crop for the ideal width of the second leaf under the top leaf, 22-58o in the early crop and 4- 12o in the late crop for the ideal top leaf angle at the active tillering stage. Based on these results, a new concept of “dynamic plant type structure” for South China double cropping super rice breeding was suggested.

Bumper harvest of super rice in south and north China

Recently,a great progress was made in breeding and cul-tivation of super rice in China.The South DemonstrationAcceptance Meeting of China Super Rice was held in Oct17,2000 in Xinchang County,Zhejiang Province.Yieldmonitoring group organized by the Department of Science,Technology and Education,Ministry of Agriculture,Chi-na,was consisting of famous rice research scientists,a-gricultural technology extension experts,and governmentofficials.In the demonstration meeting,the group investi-gated the rice growth of the demonstration field of the im-

Simulation of Potential Productivity of Early Season Rice Varieties in Different Reqions of South China

Rice is a staple food crop in China.Since the 1950’s,many new varieties havebeen used and resulted in great increase ofyield.However there were still some barriersin the nationwide extension of new varietiesdue to the insufficient information about thecharacteristics of varieties.So,it is impor-tant to find ways of determining the potential

华南双季直播稻耐淹成苗率种质筛选及比较分析

本研究旨在鉴定在华南稻区不同季节下适宜直播的水稻种质材料,以适应该地区自然条件并支持新品种培育。选取华南地区广泛使用的水稻品种及其亲本作为试验对象,分别在早季与晚季进行了大田直播淹水成苗实验(水深6 cm)。结果表明,早季直播淹水成苗率均极显著地高于晚季,且早、晚季的淹水成苗率间相关不显著(R^(2)=-0.1253)。在早季条件下,‘Francis’、‘starbonett99’、‘润丰B’、‘Kasalath’和‘粤抗1614’等5个材料展现出较高的淹水成苗率(65.0%~76.5%),并且聚类分析将这5份材料都同聚在类群I;而在晚季条件下,‘玉晶软占’和‘常规稻5’的淹水成苗率最高,分别仅为42.5%和39.5%,同样被聚在类群I。这一结果说明由于华南稻区早晚季气候特征差异,选育直播稻新品种时应考虑选择适合各自季节的淹水成苗率高的种质材料。

有机肥与石灰配施对华南酸性土壤的改良效果

为明确有机肥与石灰对华南酸性土壤的改良效果,采用田间小区试验,研究了有机肥、石灰分别单施与配施对双季稻区酸性土壤的酸化性质、水稻生长及产量的影响。试验包括5个处理:不施肥(CK)、单施控释肥(CF)、控释肥+石灰(LM)、控释肥+有机肥(OF)、控释肥+石灰与有机肥配施(CLO),除CK外,各处理养分保持一致,物料均在水稻移栽前一次性施入土壤。结果表明,CLO处理对土壤pH的改良效果最优,其pH提高了0.42个单位,而OF和LM处理的pH分别提升0.27、0.37个单位;OF处理土壤有机质含量最高,达44.46 g·kg^(-1),其次为CLO处理,达37.76 g·kg^(-1);LM、OF及CLO处理均显著降低了土壤交换性酸含量,降幅最高的处理为CLO,达71.4%。相关性分析表明,土壤交换性氢和交换性铝与pH的回归方程斜率绝对值分别为1.3568和0.1560,均呈显著负相关;LM处理的土壤交换性盐基离子总量达7.52 cmol·kg^(-1),显著高于其他处理,其次为CLO处理,达6.92 cmol·kg^(-1)。配施处理能增加灌浆期水稻叶片叶绿素含量,显著高于CK,增产效果最优。研究表明,有机肥与石灰配施较单独施用对华南酸化土壤的改良效果更好。

Reducing nitrogen application with dense planting increases nitrogen use efficiency by maintaining root growth in a double-rice cropping system

Rational nitrogen(N) application can greatly increase rice(Oryza sativa L.) yield. However, excessive N input can lead not only to low N use efficiency(NUE) but also to severe environmental pollution.Reducing N application rate with a higher planting density(RNHD) is recommended to maintain rice yield and improve NUE. The effects of RNHD on fertilizer N fate and rice root growth traits remain unclear. We accordingly conducted a two-year field experiment to investigate the influence of RNHD on rice yield, fertilizer 15N fate, and root growth in a double-rice cropping system in China. In comparison with the conventional practice of high N application with sparse planting, RNHD resulted in similar yield and biomass production as well as plant N uptake. RNHD increased agronomic NUEs by 23.3%–31.9%(P < 0.05) and N recovery efficiency by 17.4%–24.1%(P < 0.05). RNHD increased fertilizer 15N recovery rate by 14.5%–34.7%(P < 0.05), but reduced15 N retention rate by 9.2%–12.0%(P < 0.05). Although a reduced N rate led to significantly reduced root length, surface area, volume, and biomass, these root traits were significantly increased by higher planting density. RNHD did not affect these root morphological traits and reduced activities of nitrate reductase(NR) and glutamine synthetase(GS) only at tillering stage. Plant N uptake was significantly positively correlated with these root traits, but not correlated with NR and GS activities. Together, these findings show that reducing N application with dense planting can lead to high plant N uptake by maintaining rice root growth and thus increase NUE.

华南双季稻低碳高产栽培技术研究进展

分析了华南双季稻田CH4和N2O排放量,从低碳品种筛选、节水减排灌溉、化肥减量增效等方面介绍了华南双季稻低碳高产关键技术及其集成应用情况。综述了华南双季稻低碳高产栽培技术研究的主要进展、存在问题和今后工作重点。华南双季稻低碳高产栽培技术节水节肥、减排控污、增产增收,实现了低碳与高产的协调,应用前景好。目前,该技术主要存在可用品种少、种植模式单一、推广难度大等问题;今后,在加大政策支持的同时,亟需加强品种筛选、模式集成、基础理论等方面的研究,以确保国家粮食安全,实现碳达峰碳中和的目标。

华南区稻田耕地质量空间分布与产能提升潜力

为了明确华南区稻田耕地质量空间分布及其提升潜力,为实现华南区水稻高产稳产提供科学依据,本研究基于2017年农业农村部耕地质量监测保护中心在华南区开展的耕地质量区域汇总评价数据,分析华南区稻田耕地质量空间分布情况及其与产能对应关系,并利用随机森林模型明确影响产能提升的主要限制因子。华南区稻田耕地质量等级呈现“中间高,四周低”的空间分布规律;利用半方差函数拟合结果表明,华南区稻田耕地质量等级呈中度空间相关性(R2=0.95),以广东(3.82)最高,海南(5.32)最低。华南区耕地质量评价指标中,土壤养分指标空间分布差异较大,土壤全氮和缓效钾含量空间分布呈强烈的空间相关性,分别呈现“西高东低”和“北高南低”空间分布规律;土壤有机质、有效磷、速效钾含量呈中度空间分布相关性,分别呈现由西向东、由东向西、由北向南不断降低的空间分布趋势;土壤pH整体呈弱酸性(5.40)。土壤物理性状、立地条件、土壤管理情况及土壤健康状况以东部较好,西部较差。华南区稻田耕地质量等级与单产整体呈显著正相关性(R2=0.9140),水稻产量随耕地质量等级提升呈先迅速增加后趋于平缓趋势;华南区稻田耕地质量等级与水稻产量可持续指数呈显著正相关(R^(2)=0.9333)。随机森林模型的重要性分析结果表明,土壤有效磷含量、灌溉能力和土壤有机质含量是影响华南区水稻产量的最关键因素。情景模拟表明,若华南区稻田耕地质量等级分别提升0.5、1.0、1.5个等级,则水稻将增产14.93%、22.39%、29.86%,相当于节约耕地面积31.77万hm^(2)、56.35万hm^(2)、75.95万hm^(2)。华南区稻田耕地质量和产能仍有较大提升潜力,通过提升耕地质量来提升产能对保障粮食安全、促进农业绿色生产具有重大意义。

广东省水稻品种区试中对照品种的特点与趋势

【目的】归纳总结2006—2022年广东省水稻品种区域试验中对照品种的主要特性和更迭情况,阐明广东地区水稻的育种进展,为华南双季稻稻作区的水稻育种工作提供参考。【方法】根据2006—2022年广东省水稻品种区试中对照品种的相关数据,统计对照品种的更迭情况,并分析其产量、品质性状、抗病性等重要性状表现。【结果】在16年(2006—2022年)区试中一共使用过31个对照品种,这些对照品种大多具有高产、广适、抗稻瘟病的优势。其中有15个对照品种可在广东省以外地区进行推广种植,8个常规稻对照品种曾在广东省内大范围种植,3个杂交稻对照品种是被农业农村部认定的超级稻。2022年常规稻对照品种早、晚季的平均产量分别为7176.1±243.6 kg/hm^(2)和6500.9±117.08 kg/hm^(2),杂交稻对照品种早、晚季的平均产量分别为7282.0±358.6 kg/hm^(2)和6835.8±175.2 kg/hm^(2)。27个对照品种对稻瘟病的抗性达到中抗及以上水平,8个对照品种对白叶枯病的抗性达到中抗及以上水平。对照品种平均使用年限为5年,更新的对照品种主要在产量与品质方面有所提高。16年间对照品种早季的平均产量增加301.8~417.0 kg/hm^(2),晚季的平均产量增加778.20~966.15kg/hm^(2)。2022年的对照品种整体品质比2006年明显提高,谷粒长宽比从2.76提高至3.25,平均垩白度从13.4%下降至9.6%,胶稠度从57.5 mm延长至66.2 mm,整精米率从58.06%提高至60.51%。对照品种的平均直链淀粉含量从2012年开始出现下降,降幅1.2%~5.6%。【结论】2006—2021年广东省选择的水稻对照品种综合品质较好,随着生产水平的提高及时更换产量与品质更好的对照品种,且在审定过程中优中选优,令新品种的产量稳步提升、品质性状明显改良,更加符合生产发展要求。

华南籼稻早造稻米蒸煮、外观和碾米品质与食味品质的相关性研究

根据国家优质稻谷标准 GB/ T17891— 1999对 77份华南籼稻早造稻米样品进行了品质指标系统测定 ,蒸煮、外观、碾米品质与食味品质的相关性研究结果表明 :华南籼稻早造稻米的直链淀粉含量与食味品质呈极显著负相关 ;胶稠度因子对食味品质有极显著正线性效应 ,不完善粒因子对食味品质有极显著负线性关系。对食味品质的重要性顺序为胶稠度因子 >不完善粒因子 >直链淀粉含量因子 >垩白粒率因子。

华南地区不同品系水稻积累砷特征及其影响因素

选用华南地区较为常见的杂交稻、优质常规稻2个水稻品系,16个水稻品种,通过土壤盆栽试验,待其成熟收获后,分析水稻根表、根部、秸秆、糙米中砷含量及相关影响元素的含量,旨在研究不同水稻品系（种）对砷吸收、转运和积累规律以及其影响因素,为低积累、高耐性水稻品系（品种）的选择及相应的农业措施提供科学的理论依据。结果表明,砷在水稻中的分布情况为根表〉根部〉秸秆〉糙米;供试的糙米中砷含量为0.18~0.47mg.kg-1,均符合国家卫生标准（GB4810—1994）。水稻根表铁锰膜中砷含量随根表中铁、锰的增加而富集,相关分析表明,根表铁锰膜形成可以有效降低糙米砷积累,而秸秆磷可以有效降低秸秆中砷的积累。杂交稻各部位的砷含量及转移系数均高于常规稻,且秸秆和糙米砷含量差异达到显著水平;天优122的糙米砷积累能力高于其他品种,美香占2号低于其他品种。

华南主栽高产籼稻根系形态特征及其与产量构成的关系

为探明不同类型高产籼稻的根系形态特征差异及其与产量的关系,以7个目前在华南地区大面积推广应用的主导品种(组合)合美占、桂农占、玉香油占、粤晶丝苗2号、五优308、天优998、天优122为材料,在2010—2011年进行两年盆栽试验,分别考察分蘖盛期、抽穗期及成熟期的单株、单茎及单条不定根形态性状,利用WinRhizo根系分析系统分析抽穗期的根系分枝特征,并计算根系形态特征与产量的相关性。结果表明:(1)杂交籼稻组合各生育时期的单株根数、单株根长、单茎根长及单条根长均显著大于常规籼稻品种;单株和单茎的根体积与干重差异不明显;常规稻单条根质量则普遍高于杂交稻。(2)抽穗期不同级别根的表面积和体积均为不定根>粗分枝根>细分枝根,杂交稻不同级别根的总长度为粗分枝根>不定根>细分枝根,常规稻则为不定根>粗分枝根>细分枝根;杂交稻的分枝根总长度及粗分枝根和细分枝根的长度、表面积、体积都显著大于常规稻;常规稻的平均根直径则显著大于杂交稻。(3)杂交稻与常规稻根系特征的主要差异是单株根数和长度的差异,分蘖数和单条根长度的差异是两者根系特征差异的重要原因。(4)单株不定根数、不定根总长、根干重等12个根系性状分别与产量显著或极显著正相关;单株不定根数和分枝根总表面积分别是影响产量的主要因素。这些结果为水稻根系遗传改良和超高产育种及栽培提供了参考。

华南籼稻晚造稻米蒸煮、外观和碾米品质与食味品质的相关性研究

根据国家优质稻谷标准GB/T17891 1999,对 6 0份华南籼稻晚造稻米样品进行了品质指标系统测定。蒸煮、外观、碾米品质与食味品质的相关性研究结果表明 :华南籼稻晚造稻米的直链淀粉含量、垩白粒率和垩白度与食味品质呈极显著负相关 ,胶稠度和粒型与食味品质呈极显著正相关 ;主成分分析表明 :入选的 3个主成分值分别被称为垩白粒率因子、出糙率因子和胶稠度因子。出糙率因子对食味品质有极显著正线性效应 ,垩白粒率因子对食味品质有极显著负线性关系。对食味品质的重要性顺序为出糙率因子 >垩白粒率因子 >胶稠度因子。

华南地区常规籼稻品种产量和株型性状的遗传改良

【目的】研究矮化育种以来华南地区常规籼稻品种产量与株型性状的改良及其关系,为进一步提高品种产量潜力探索新的突破方向。【方法】以华南地区自矮化育种以来育成推广的65个主要栽培品种为试验材料,通过在相同生态和栽培条件下的栽培试验,研究不同年份育成品种产量和株型性状的演变,将植株形态性状与产量性状进行相关分析,并将几个主要产量性状与产量进行通径分析。【结果】从矮化育种开始,华南地区常规籼稻品种产量水平不断提高,至20世纪80年代中期达到最高水平,随后产量水平处于停滞状态,直到2000年又开始形成上升趋势。品种株高随育成年份缓慢上升,但上升幅度不大;在叶形性状中,上三叶长和上三叶宽未有明显变化,但上三叶基角和上三叶曲率则有较显著的改良;穗粒性状中单株穗数和结实率逐渐降低,一次枝梗数、二次枝梗数和每穗粒数则呈线性增加,千粒重呈阶梯式下降;单株库容量、单株生物产量和单株产量表现为20世纪50年代至80年代中后期显著上升,随后上升趋势停滞。【结论】自矮化育种以来,华南地区常规籼稻品种产量水平显著提高,但自20世纪80年代中后期开始未能取得进一步突破。在株型性状的遗传改良方面,叶片形态性状改良显著,品种由大粒穗数型向小粒大穗型演进。今后品种改良的重点是通过株型改良提高库容量。

试论华南早籼稻的品质育种策略

总结了 80年代以来广东省优质稻遗传研究和华南早籼优质稻育种实践和探索 ,讨论了华南早籼优质稻育种策略 ,指出当前华南早籼应重点加强中等直链淀粉含量优质稻选育 ,系统开展美国优良品种优质特性和高光效性能研究 ,实现洋为我用 。

南方粳型超级稻物质生产积累及超高产特征的研究

以超级粳稻品种武粳15、淮稻9号、徐稻3号和常优1号为材料,对高产（8.25~9.75thm？2）、更高产（9.75~11.25thm？2）和超高产（〉11.25thm？2）3个产量等级群体的物质生产与产量的关系、干物质积累、输出与转运等方面进行了系统的比较研究。结果表明,4个超级稻品种成熟期、抽穗至成熟期的干物质重与产量呈极显著正相关,抽穗期干物质重均与产量呈抛物线关系,拔节至抽穗期的干物质重与产量呈极显著正相关（高产—更高产、更高产—超高产以及将3个产量等级综合起来）;从高产到更高产再到超高产,4个超级稻品种的生物学产量不断提高（差异显著）,而超高产群体的经济系数则与更高产水平相当（0.5000以上）,显著高于高产水平;较之更高产、高产群体,超高产群体在生育中期（拔节至抽穗期）干物质积累量大,抽穗期叶面积指数高、株型挺拔、群体质量优[有效叶面积率、高效叶面积率、总颖花量与颖花/叶（cm2）、基部节间粗、单茎茎鞘重均高],在生育后期（抽穗至成熟期）,光合能力强（叶面积衰减率小,光合势、群体生长率、净同化率均高）、干物质积累量高（占生物学产量的40.0%以上）、茎鞘物质的输出与转运协调[实粒/叶（cm2）、粒重（mg）/叶（cm2）均高]。

华南双季超级稻分蘖盛期理想形态性状研究

对华南稻区最新育成的超级杂交稻组合粤杂122、丰优428、泗优998、培杂67和超级常规稻品种广超3号、胜泰1号分蘖盛期早、晚不同季节的形态性状进行了研究。利用方差、通径、判别函数分析等统计方法,确定了华南双季超级稻分蘖盛期的理想形态性状量化指标,即,植株高度:早季55～60cm、晚季60～76cm;每蔸茎蘖数:早季15条左右、晚季14～19条;顶下1叶长:早季40～44cm、晚季42～60cm;顶下1叶宽:早季1.2～1.4cm、晚季1.2～1.3cm;顶下2叶长:早季39～44cm、晚季37～43cm;顶下2叶宽:早季1.1～1.4cm、晚季1.1cm左右;顶叶开张角:早季22～58°、晚季4～12°。并在此基础上提出了华南双季超级稻“动态株型结构”育种的新概念。