水稻理想株型的研究进展

介绍了理想株型的涵义及发展历史,并从茎、叶片、穗、根系等4个方面,对水稻理想株型的研究进展进行了综述,提出了理想株型必须适应当地生产实际和生态条件、建立生态适应理想株型育种指标数学模拟体系等未来水稻理想株型研究的6个方向。     

水稻理想株型的性状研究

在前文“初探超级稻育种与理想株型”中,已就理想株型的理论,发展阶段以及与超级稻育种的关系做了探讨,本文将在此基础上对水稻理想株型的有关性状研究分别加以阐述。一、株高植株高度是衡量水稻对N肥反应灵敏性的一个重要指标,而且植株的抗倒性也主要由株高所决定的（Yoshita,S．1972,Jenming,P．R．等．1979）。至于与植株的光合作用和生长发育紧密相关的群体内通风透光状况更是受着植株高度制约的（黄耀祥等,1983）。缩短茎秆是株型育种初期即矮化育种的核心内容,早期认为矮秆的主要作用是增强耐肥抗倒。适于密植和提高经济…     

水稻理想株型的研究进展

本文就水稻理想株型的特征特性和株型栽培的研究现状进行了综述,并提出了争后水稻株型研究的方向。     

水稻理想株型育种研究进展

理想株型与杂种优势利用相结合是实现水稻单产突破的重要途径之一。综述了理想株型的概念、株型构成因子及其相互关系、国内外株型育种的主要理论及存在的问题。提出了动态理想型的株型观点和水稻动态理想型的主要塑造途径,对水稻动态理想型育种进行了展望。     

浅谈水稻理想株型育种

简述了理想株型的发展历史及株型育种经历的三个发展阶段,阐述了理想株型的形态特征、理想株型育种的理论基础、应用这一理论所取得的成果以及发展前景。提出了进一步发挥水稻的高产潜力是理想株型与杂种优势利用相结合。     

水稻理想株型研究综述

理想株型与杂种优势利用相结合是实现水稻单产突破的重要途径之一。本文综述了理想株型的概念、发展历史、各株型构成因子研究状况和存在的问题。阐述了理想株型与环境优势达到最大的统一才能使水稻获得高产优质的观点,并提出了实现这一观点应采取的措施。     

浅谈水稻理想株型育种

简述了理想株型的发展历史及株型育种经历的三个发展阶段，阐述了理想株型的形态特征、理想株型育种的理论基础、应用这一理论所取得的成果以及发展前景。提出了进一步发挥水稻的高产潜力是理想株型与杂种优势利用相结合。     

水稻株型的研究进展

水稻是中国种植面积最大的粮食作物,其产量是人们一直关注的课题.由于人口不断增长、水稻种植面积有限、农民种植积极性不高及自然灾害等原因,粮食安全问题仍日益突出,如何保持水稻持续性产出和提高水稻产量依旧是大家关注的重点.水稻株型与产量密切相关,主要综述水稻株型研究进展,并展望理想株型今后发展方向.     

华南双季超高产水稻抽穗期理想株型结构研究

 对华南稻区新育成的超高产杂交稻组合粤杂122、丰优428、泗优998、培杂67和超高产常规稻品种广超3号、胜泰1号等6个材料抽穗期的主要形态性状进行了差异显著性测验及对产量的通径分析,提出了华南双季稻超高产育种抽穗期理想形态指标分别为：早季株高90~105 cm;每蔸茎数11~12条;剑叶长35~40 cm;剑叶宽2.1~2.2 cm;倒2叶长、宽为46~50 cm和1.8~2.1 cm;倒3叶长、宽为59~64 cm和1.4~1.9 cm;剑叶开张角7~14;倒2叶、倒3叶开张角为18 和20~33。晚季株高95~100 cm;每蔸茎数9~15条;剑叶长30~41 cm;剑叶宽1.8~2.0 cm;倒2叶长、宽为53~61 cm、1.3~1.8 cm;倒3叶长、宽为52~58 cm、1.2~1.5 cm;剑叶开张角9 ~19;倒2叶、倒3叶开张角为15~37、16~49。同时测定了参试材料的主要生理性状,并对华南双季稻超高产育种抽穗期的适宜生理指标进行了探讨。     

水稻理想株型的遗传基础研究

水稻是我国最主要的粮食作物之一,20世纪50年代矮源基因在育种中的应用和70年代杂种优势的利用使水稻产量实现了两次飞跃。近年来,虽然水稻产量徘徊不前,但基于理想株型的综合设计让水稻产量的新突破成为可能。本文从水稻根、茎、叶、穗、分蘖等几部分的遗传进展综述了水稻理想株型的设计塑造。     

Canopy leaf area and leaf mass in the upper stratum of Urochloa hybrid ‘Mavuno’ grass subjected to nitrogen fertilisation

Nitrogen (N) inputs are recognised to maximise herbage mass (HM) in tropical perennial grasses, whereas less is clear on their impact on HM distribution and the effects on leaf mass (LM) and leaf area index (LAI) in the upper stratum. This 2 year study, carried out in Pirassununga, Brazil, assessed the HM distribution in the upper (>20 cm) and lower (<20 cm) strata in Urochloa hybrid ‘Mavuno’ grass maintained under similar pre- and post-cutting canopy heights with contrasting N fertilisation rates applied after each cutting (no-nitrogen, 15, 30, and 45 kg N ha⁻¹). The relevance of specific leaf area (SLA), leaf N concentration (NLeaf), tiller weight (TW) and population density to the LM and LAI of the upper stratum were also examined. Mavuno grass expressed a stable HM < 20 cm (59%–71% during Year I and 66%–80% for Year II), and apparent N fertilisation impacts on HM > 20 cm were verified at specific regrowth cycles during Year II. Mavuno grass pastures expressed plasticity for adjustments on leaf, tiller and population attributes, which were modulated by both climatic conditions and N fertilisation. Under favourable growth conditions during Year I, fertilised pastures were able to sustain higher NLeaf and SLA but associated with lower TW, resulting in maximisation of LAI but not in LM in the upper stratum. During Year II, fertilised pastures expressed higher NLeaf, SLA, number of basal tillers, despite the lowest TW, which resulted in higher LAI and LM in the upper stratum compared with non-fertilised pastures. Our results highlighted that adjustments on leaf and population attributes within the canopy were driven to maximise the upper stratum LAI, being positively affected by N fertilisation.     

The relationship between tiller appearance in spring and contribution to dry-matter yield in perennial ryegrass (Lolium perenne L.) cultivars differing in heading date

The relative contribution of tillers present in April and those appearing in consecutive periods in spring was assessed for perennial ryegrass cultivars in the three maturity groups (early, intermediate‐ and late‐heading). Each group was represented by two diploid and one tetraploid cultivar each in plots in their third (2000) and fourth (2001) harvest years in three replicated blocks receiving an average of 325 kg N ha^?1 and cut seven (in 2001) or eight (in 2000) times annually. ‘Main’ tillers and their daughters were marked with colour‐coded PVC‐covered wire loops in early April as were daughters which appeared in consecutive periods between harvests, the loop colour identifying the period of origin of the tiller. Tillers were harvested at cutting height (5 cm) before the plots were harvested and the herbage from tillers with the same colour code bulked per plot. Tillers were identified retrospectively as ‘reproductive’ if they had been decapitated at the previous harvest. Dry‐matter yield was higher in the early than late‐heading cultivars in April and early May but this was reversed in harvests in late May and June. The early heading group had a lower lamina content than the late‐heading group during reproduction growth, both due to the reproductive tillers (mainly those which overwintered) having a lower leaf content and to their being fewer and smaller vegetative tillers during the reproductive phase than for the late‐heading group. Turnover of tillers was high in spring due to decapitation of reproductive tillers and rapid post‐flowering tillering. This was particularly pronounced in the early heading group which also had slightly more tillers marked in April which were subsequently decapitated than in the other maturity groups, i.e. 0·56 compared with 0·44 for the late‐maturing group. Mean ratios of rate of death: rate of tillering for 3 years (1999–2001) for the early and late‐heading groups were 0·8 and 0·4, respectively, for April–May and 1·1 and 2·4, respectively, for June indicating the different patterns in tiller turnover for the two extreme maturity groups. Information on tiller origin and contribution to yield can be used to refine tiller‐based grass growth models.     

龙吉稻田稻蛀螟发生为害及螟害株密度零频率估计法

稻蛀螟类是水稻常见害虫,为查明稻蛀螟发生为害情况和探索在一定精度保证前提下简便、快捷地估计螟害株密度的方法,对海南省澄迈县老城镇龙吉村稻田稻蛀螟发生为害进行了系统调查,并利用稻丛螟害株密度m和稻丛螟害零频率P0分别拟合线性函数、二次函数、双曲线函数、指数函数、幂函数、对数函数等常用函数模型及Gerrard-Chiang模型和Wilson模型。结果表明,龙吉稻田发生的稻蛀螟种类为三化螟[Scripophaga incertulas(Walker)]和大螟[Sesamia inferens(Walker)],其中早稻以大螟为主,晚稻则以三化螟占优;早、晚稻的螟害株密度从分蘖后期至乳熟期均呈先上升而后下降趋势,晚稻分蘖后期的螟害株密度明显高于早稻同生育期的,而早、晚稻的螟害株密度在孕穗期、抽穗期和乳熟期等同生育期间的差异不显著;用螟害零频率估计早、晚稻和早-晚稻螟害株密度的最优模型分别为Gerrard-Chiang模型m=1.164 9(-ln P0)1.045 4、双曲线函数模型m=-0.943 5+0.951 3/P0和m=-0.952 5+0.958 3/P0。应用这些模型在相应稻季可根据三化螟和大螟为害的零频率便捷、有效地估计螟害株密度。     

木薯新品种‘华南16号’的选育

新品种‘华南16号’（‘SC16’）（Manihot esculenta Crantz cv. SC No.16）是以木薯品种‘华南8号’（‘SC8’）为母本和引进品种‘Q10’（I93/0665）为父本进行人工杂交获得F₁杂交种子,经实生苗试验、初级品比、高级品比、区域试验和生产性试验等选育而成。其鲜薯产量在区域试验和生产性试验分别为50.15 t/hm²和45.82 t/hm²,比我国主栽品种‘华南205’（‘SC205’）分别增产55.45%和35.85%;块根淀粉率分别为25.42%和26.10%,略低于‘SC205’（对照）;鲜薯氰苷含量为29.70 μg/g,属于甜木薯品种。综合试验结果表明,‘华南16号’是1个株型优良、高产,且能够密植与机械化采收的工业用、食用兼饲用的新品种,适宜在我国广西、广东沿海、海南,以及东南亚地区推广种植。     

杀秧机及不同化学制剂对马铃薯杀秧效果比较试验

马铃薯杀秧措施已经广泛应用于脱毒马铃薯种薯生产中,但实际调查中杀秧效果和杀秧成本,有很大的差异,针对这一问题,本试验选出常用的杀秧机和硫酸铜、百草枯两种化学制剂进行杀秧处理,并对马铃薯的杀秧效果进行了综合比较。结果表明,自制2垄马铃薯杀秧机效果最好,其杀秧成本低,利于机械收获,安全性高,是可以大力推广的技术措施。     

Size/density compensation in Chloris gayana Kunth cv. Fine Cut subjected to different defoliation regimes

The study evaluated the plasticity of Chloris gayana Kunth cv. Fine Cut to defoliation in terms of tiller size/density compensation (SDC). Twelve mini‐swards were grown in a greenhouse under non‐limiting water and nutrient availabilities for 188 d. Four defoliation treatments were applied as a factorial arrangement of two defoliation frequencies and intensities: 80L, 80H, 100L and 100H (80 and 100 denote percentage of photosynthetically active radiation intercepted at defoliation; L and H denote stubble LAIs of 0·6 and 1·75, respectively). Tiller density, demography, dry weight, leaf area and volume were determined over the final 77 d of the experiment. SDC was observed across 80H and both 100 treatments. The estimated slope of the relationship between tiller size and density was close to ?5/2, the deviation from the ?3/2 line proposed for undefoliated swards being related to changes in LAI and tiller leaf area/volume ratio. The most severe defoliation regime, 80L, resulted in a lower tiller population density relative to the compensation line, suggesting that this defoliation management shifted the species beyond its range of phenotypic plasticity. Cumulative herbage production was significantly reduced in 80L. Despite the similar herbage production of 80H and both 100 treatments, the former was the most favourable defoliation regime for optimizing leafiness and productivity.     

Influence of sward condition on leaf tissue turnover in tall fescue and tall wheatgrass swards under continuous grazing

Two experiments were carried out on a tall fescue sward in two periods of spring 1994 and on a tall wheatgrass sward in autumn 2001 and spring 2003 to analyse the effect of sward surface height on herbage mass, leaf area index and leaf tissue flows under continuous grazing. The experiment on tall fescue was conducted without the application of fertilizer and the experiment with tall wheatgrass received 20 kg P ha^?1 and a total of 100 kg N ha^?1 in two equal dressings applied in March (autumn) and end of July (mid‐winter). Growth and senescence rates per unit area increased with increasing sward surface height of swards of both species. Maximum estimated lamina growth rates were 28 and 23 kg DM ha^?1 d^?1 for the tall fescue in early and late spring, respectively, and 25 and 36 kg DM ha^?1 d^?1 for tall wheatgrass in autumn and spring respectively. In the tall fescue sward, predicted average proportions of the current growth that were lost to senescence in early and late spring were around 0·40 for the sward surface heights of 30–80 mm, and increased to around 0·60 for sward surface heights over 130 mm. In the tall wheatgrass sward the corresponding values during spring increased from around 0·40 to 0·70 for sward surface heights between 80 and 130 mm. During autumn, senescence losses exceeded growth at sward surface heights above 90 mm. These results show the low efficiency of extensively managed grazing systems when compared with the high‐input systems based on perennial ryegrass.