花生双受精过程及其经历时间

通过石蜡切片技术研究了花生双受精作用的全过程, 结果表明, 开花后1 h花生的花粉管内的生殖细胞进入有丝分裂, 大约3 h完成。开花后8 h左右精子已经释放到胚囊, 开花后9~13 h精核分别与卵细胞和极核或次生核融合。卵细胞受精之后, 直到开花后30 h合子中的2个核仁渐渐融合, 进入分裂期, 合子多数是横分裂, 少部分纵分裂, 开花后32 h合子分裂形成二细胞原胚。合子休眠期为19 h, 极核在受精之前一部分融合成次生核, 极核或次生核受精之后, 在开花后13 h几乎大部分融合结束, 其中的一个极核或次生核中出现雄性核仁, 形成初生胚乳核, 初生胚乳核不经休眠或极短时间的休眠在开花后15 h分裂。本研究提供了花生受精过程的雌雄性细胞融合形态变化与相应经历的时间。确定了花生合子休眠期, 丰富了花生胚胎学资料, 对花生育种、转基因操作等具有重要意义。     

Yield stability in common bean (Phaseolus vulgaris L.) genotypes

An experiment was undertaken to determine the stability of seed yield in 21 common bean genotypes representing three growth habits. Seven genotypes in each growth habit (determinate bush, indeterminate bush and indeterminate prostrate) were evaluated in replicated trials at three locations for three years under rain fed conditions in Ethiopia. A combined analysis of variance, stability statistics and rank correlations among stability statistics and yield-stability statistic were determined. The genotypes differed significantly for seed yield and genotype × environment (year by location) interaction (GE). The different stability statistics namely Type1, Type 2 and Type 3 measured the different aspects of stability. This was substantiated by rank correlation coefficient. There were strong rank correlations among S_i ²d, W_i ²,σ_i ² and S_i ², where as there was weak correlation between b_iand R_i ², S_i ²d, W_i ², σ_i ² and S_i ². R² was significantly and negatively correlated with W_i ², σ_i ² and S_i ². σ_i ² is significantly correlated with W_i ².Yield is significantly correlated with b_i and R_i ².None of the statistics per se was useful for selecting high yielding and stable genotypes except the YS(yield-stability statistic). Most of the high yielding genotypes were relatively stable. Of the 21 genotypes, only 11genotypes were selected for their high yielding and stable performance. Genotypes with growth habit III and I (in determinate prostrate and determinate bush) were generally more stable than in determinate bush. This revised version was published online in July 2006 with corrections to the Cover Date.     

Compensation-Induced Yield Gains in Mixtures of Common Bean (Phaseolus vulgaris L.)

Over the course of two planting seasons field trials were conducted at the CIAT farm in Palmira (Colombia). The experiments included nine tropical bean lines grown in pure stands and seven mixtures obtained by combining these lines on the basis of equal proportions in seed number.
In the case of several pure lines, inferior seed quality led to low germination and uneven population densities, especially in the first planting season. Analogously, missing plants also occurred with the corresponding mixtures. A significant and positive relationship between mixing induced yield gains and patchiness in mixtures was found, indicating that intergenotypic compensation was a major determinant for mixture effects on yield. In common bean as a tropical subsistence crop seed quality is known to be erratic. It is concluded that compensation effects in mixtures of common bean may be expected to be of practical importance regarding the improvement of yield stability over seasons.     

施肥量对甜菜产量和质量的影响

采用"3414"最优回归设计方法,对甜菜氮磷钾肥料合理配施进行研究。结果表明,氮磷钾配合施用显著提高了甜菜产量,三因素增产大小顺序为N>P>K。本试验条件下,N、P2O5和K₂O最大施用量分别为198.51kg/hm²、115.97kg/hm²和103.63kg/hm²,三要素比例为1∶0.584∶0.522时,甜菜块根产量最高为65005.59kg/hm²。在同等肥力下,含糖率随着施氮量的增加而下降,随着磷肥的增加而升高,钾肥对含糖率影响不大。     

Effect of Phosphorus and Nitrogen Fertilization on Sunflower (Helianthus annus L.) Nitrogen Uptake and Yield

Little is known about the effect of combined phosphorus and nitrogen (P‐N) fertilization on the N requirement of sunflower (Helianthus annus L.). This study was carried out to evaluate the effects of varying levels of P and N, as well as the interaction P × N, on the N uptake, yield and N apparent utilization efficiency under field conditions. Split‐plot design experiments were conducted in the mid‐western Pampas in Argentina. Four levels of N (0, 46, 92 and 138 kg N ha^?1) and three levels of P (0, 12 and 40 kg P ha^?1) were applied to two Typic Hapludolls over two growing seasons (1997–98 and 1998–99). N uptake and soil N‐NO₃ contents were determined at the V₇, R₅ and R₉ growth stages. The sunflower yield ranged from 2.5 to 5.0 Mg ha^?1. The total N requirement was around 45 kg N Mg^?1 grain, and this result suggests that it is not necessary to use different N requirements (parameter b) for fertilized crops when a yield response is expected. To achieve a 100 % yield maximum a N supply (soil plus fertilizer) of 181 kg N ha^?1 at P₄₀ was needed. However, at P₀, the highest yield was about 80 % of the maximum yield with a N supply (soil plus fertilizer) of 164 kg N ha^?1. P application increased the apparent use efficiency of the supplied N.     

栽培甜菜中央细胞受精前后的超微结构

应用透射电镜技术比较栽培甜菜(Beta vulgaris)中央细胞受精前后的超微结构特征,以完善甜菜生殖生物学研究,并为相关研究提供基本资料。结果表明,中央细胞在受精前后的超微结构变化主要表现于核及核周围胞质。中央细胞的2个极核融合较早,在花蕾时期即以次生核形式存在,具双相核仁,可明显分辨纤维区和颗粒区;有的有额外小核仁和核仁液泡。核周围的细胞质中具丰富的细胞器且功能活跃,包括线粒体、质体(含或不含淀粉粒)、高尔基体、核糖体和粗面内质网。受精后,形成初生胚乳核,核周围胞质中变化最大的是质体,形成众多变形质体,形态多样,且富含淀粉粒。初生胚乳核分裂过程中,核仁消失,核膜崩解为囊泡状结构,粗面内质网减少,滑面内质网增加。分裂形成2个胚乳游离核,核周围胞质与初生胚乳核相似。总之,中央细胞在受精前后的超微结构特征均呈现代谢活跃状态。     

Root Yield and Quality of Sugar Beet (Beta vulgaris L.) in Relation to Plant Population

Introduction of genetic monogerm seed and the advancement of agricultural techniques raised the possibility of eliminating costly thinning operations in sugar beet farming. However, this requires high and uniform seedling emergence to provide prerequisite plant populations in the field. This work investigated the minimum levels of seedling emergence for non-thinned sugar beet farming. The experiment was carried out in a loamy soil to investigate the effects of three levels of emergence (60, 50 and 35%) and two intra-row spacings (8 and 15cm) with or without thinning using seed source of graded viability of cv Eva in 1992 and 1993 under field conditions in Eastern Anatolia. Plant population throughout the growing period was monitored and data were taken of yield and quality parameters. On average, 60, 50 and 35% emergence levels were achieved using seed source of 90, 72 and 54% viability range, which resulted in different levels of plant stands depending on intra-row spacing and thinning. Plant density at harvest ranged between 49 500 and 124 500 ha⁻¹ on average depending on initial establishment, intra-row spacing and thinning. Root yield and sugar yield were the highest at plant stands between 90 000 and 100 000 ha⁻¹, below or above of which declined. Impurity contents (e.g. Na, K and a-amino N contents) and extractable sugar content decreased but sugar content and clear juice purity enhanced as plant stands at harvest increased.     

苏格兰型留兰香优质高产栽培技术研究

为了探索苏格兰型留兰香的优质高产栽培技术,对影响其产量和品质的主要农艺措施（如播期、密度、配方施肥、最佳收获期等）进行综合研究。结果表明苏格兰型留兰香精油产量≥82.5kg/hm2且品质优的农艺措施的优化方案为：播期11月7日—11月22日（即立冬至小雪）,密度25.1~36.2万苗/hm2,施肥量纯N 169.2~214.5 kg/hm2、P2O5 91.8~134.0 kg/hm2,最佳收获期为主茎10%左右的花蕾开花期。     

不同的施肥用药组合对黄瓜产量及成本效益影响的研究

为了黄瓜种植时合理的施用肥料和农药提供参考,缓解当前严重的环境污染和蔬菜农药残留超标问题,探讨不同的施肥用药情况对黄瓜产量以及成本投入的影响。以黄瓜为试材,设置4个不同的处理,分别为T1(习惯施肥+习惯用药,CK)、T2(习惯施肥+推荐用药)、T3(推荐施肥+习惯用药)、T4(推荐施肥+推荐用药)。结果表明:T4处理在肥料和药剂的种类数量上比对照处理少得多,并且对黄瓜的产量还起到了增产的作用,在黄瓜全采收期增产了7003.5 kg/hm~2,增产率达到了19.25%;在节本增效上效果也显著,跟对照相比,T4处理节本达到10941元/hm~2,增效达到31951.5元/hm~2。该试验获得了理想的结果,以较低的投入得到了较高的收益,可以为黄瓜种植者在肥料选择和喷施农药时提供参考,为缓解现在日趋严重的农田土壤生态环境奠定基础。     

Genetics of Seed Yield and its Components in Common Bean (Phaseolus vulgaris L.) of Middle-American Origin

Genetic variance, heritability, and expected response from selection arc useful in devising alternative methods and criteria of: selection. The objectives of this study were to estimate these for seed yield and its components from 200 F₂: populations involving 80 cultivars and lines of mostly small-seeded dry bush bean (Phaseolus vulgaris L.) of habits growth I, II, and III of Middle-American origin. All cultivars and lines were crossed in eight sets of ten parents each in a Design II mating system. The F₂ populations, without parents, were evaluated in the field in a replicates-in-sets design at two locations in Colombia in 1983. Estimates of additive genetic variance were significant for yield, pods/m², seeds/pod, and seed weight. Interaction with environments was also significant. Values for nonadditive genetic variance were not significant for either yield or yield components. The estimates of narrow sense heritability, based on the F₂ population mean and unbiased by genotype x environment interaction, were 0.21 ± 0.13 for yield. 20 ± 0.13 for pods/m², 0.57 ± 0.13 for seeds/pod, and 0.74 ± 0.15 for seed weight. The expected direct response from selection of the top 20 % of F₂ populations for yield per se would result in a 4.30 % increase in yield with a correlated response of 0.21 % in seed weight. In contrast, the expected gain from direct selection for seed weight would result in a 11.76 % increase in seed weight with a, correlated gain of 0.28 % for yield. Direct selection for pods/m² would decrease yield, seeds/pod and seed weight, while direct selection for seeds/pod would reduce pods/m² and seed weight but increase seed yield by 0.37 %. Data on yield from replicated trials in the early segregating generations could be utilized for identification and selection of promising crosses and families or lines with crosses for dry bean yield improvement.     

Yield Formation in Mixtures of Rust Resistant and Susceptible Plants of Common Bean (Phaseolus vulgaris L.)

In a two-factorial trial, conducted in 1986 at the CIAT farm in Palmira (Colombia), the performance of nine tropical bean lines differing in resistance to rust and seven mixtures obtained by combining these lines on the basis of equal proportions in seed number was evaluated in a rust inoculated treatment and in a fungicide treated control.
Compared to the fungicide treated control, rust attack significantly reduced the yield of all susceptible lines by 24 to 56% in pure stands. In rust inoculated mixtures containing resistant, intermediate and susceptible genotypes, mixture effects on yield increased only by 3.3% compared to the fungicide treated control. In mixtures of common bean a higher proportion of resistant lines appears to be required compared to cereals for comparable reductions in the spread of rust due to lower plant density and correspondingly higher autodeposition rate of uredospores.     

施肥和覆膜垄沟种植对旱地红芸豆耗水特征及产量效应的研究

[目的]为了探明在高寒冷凉区芸豆生长的水肥耦合效应,[方法]采用田间试验法,研究了施肥和覆膜垄沟种植对旱地芸豆耗水特征、水分利用效率及产量的影响。[结果]结果表明,在底墒较好,降水丰富的年份,施肥和覆膜垄沟种植的产量与农户模式相比,均有显著提高,单株荚数是其产量提高的关键因素;高肥具有明显的增产和提高水分利用效率的作用,在此基础上的覆膜垄沟种植可有效的减少土壤水分损耗,而显著的提高水分利用效率。[结论]在高寒冷凉区,水分和养分都是作物生长的限制因子,在施肥和覆膜垄沟种植方式下,水肥互作效应显著,能够大大的提高产量和水分利用效率。     

施肥对不同株型绿豆品种生长发育及产量的影响

为了探讨施肥对不同株型绿豆品种生长发育及产量的影响,采用磷酸二铵做种肥进行了不同施肥水平处理试验。结果表明:不同株型的绿豆品种都是以适量施肥(150 kg/hm2)处理的产量最佳,说明适量施肥能够促进绿豆的生长发育,从而可提高绿豆的产量。蔓生株型辽绿6号的各施肥处理的产量都高于直立株型辽绿5号的产量,说明辽绿6号比辽绿5号的增产潜力大。     

Genetics of Seed Yield and Its Components in Common Beans (Phaseolus vulgaris L.) of Andean Origin

A broad spectrum of rapeseed (rape) lines as well as resynthesized (resyn) genotypes of B. napus were analyzed for their contents of sinapoyl esters. In the rape material the concentrations varied between 17.8 and 71.9 μol/g defatted seed meal and exhibited a heritability of h²= 0.6. The resyn genotypes showed an even smaller variation but had a similar heritability. Therefore, no additional, immediately usable, genotypes with low sinapoyl ester concentrations could be created by a resynthesis.     

Breeding for yield in dry bean (Phaseolus vulgaris L.)

Strategies employed by dry bean breeders to improve yield include early generation testing, ideotype breeding, selection for physiological efficiency, and selection based on genotypic performance and combining ability across gene pools of Phaseolus vulgaris. Ideotype breeding has been successfully deployed to improve yield in navy, pinto and great northern seed types. The ideotype method is based on an ideal plant architecture to which breeders target their selection. Breeding for physiological efficiency is important in combining increased biomass, high growth rates and efficient partitioning. Genotypic performance and combining ability are also critical for yield improvement, since crosses between gene pools can exhibit negative combining ability and problems with lethality, whereas interracial crosses within the same gene pool exhibit the greatest potential. Breeders must work within specific constraints for growth habit, maturity, seed quality and disease resistance. A three-tiered pyramidal breeding strategy is proposed to facilitate yield improvement in dry bean. Breeding of elite, agronomically acceptable germplasm within the same market class is restricted to the apex of the pyramid. The intermediate level has fewer constraints and greater access to diverse germplasm. Interracial crosses within the same gene pool are utilized to exploit genetic differences within adapted material. Extracting genetic diversity from unadapted sources, including wild germplasm and other Phaseolus species, is conducted at the base of the pyramid. The objective of this breeding strategy is the movement of improved germplasm towards the apex, using different breeding procedures to optimize improvement at each tier of the breeding pyramid. This revised version was published online in July 2006 with corrections to the Cover Date.     

Breeding for yield, in mixtures of common beans (Phaseolus vulgaris L.) and maize (Zea mays L.)

Summary Despite the growing industrialization, technification and transformation that is happening in the agriculture around the world, and despite that agricultural research has always concentrated its effort on sole crops, multiple cropping systems have historically been important for common bean production in tropical countries. The reasons for this fact, are economical and social, as well as biological. Bean breeders have always been questioned on their work, because the development of new varieties is usually done in sole crop, but the varieties are grown in either systems. This paper addresses a set of questions that are usually presented to the breeders, in light of the evidence obtained from many trials conducted in Brazil and in the U.S.A.: Will the genotypes bred for sole crop conditions, perform well when grown in intercrop; How different should a genotype be, for cultivation in intercropping compared to genotypes developed for sole crop conditions; Is there a need for special breeding programs for intercropping and How could a breeding program focus the question of multiple (associated) cropping?     

根系分区施肥对黄瓜植株生长与果实产量的影响

【目的】优化植株根系供肥方式，是黄瓜高效栽培的关键。【方法】分别以“津绿露优”与“中农203”黄瓜品种为试材，研究了根系分区施肥对黄瓜植株生长与果实产量的影响。【结果】在黄瓜植株各1/2根区分别采用标准溶液与半倍标准溶液施肥时，施肥总量减少了25%，植株总鲜重与果实产量并没有显著降低；在采用两倍标准溶液与清水以及倍半标准溶液与半倍标准溶液时，施肥总量不变，但植株总鲜重分别显著增加了23.2%和16.6%，果实鲜重显著增加了34.2%与27.1%。【结论】黄瓜根系分区施肥可以达到节约施肥或者增加植株生长量与果实产量的目的     

Male sterility in beans (Phaseolus vulgaris L.)

Summary Male sterile bean plants were discovered at Embu Agricultural Research Station, Kenya. The character is controlled by one recessive gene.The Grain Legume Project is a joint project of the Kenya Ministry of Agriculture and The Netherlands Ministry of Foreign Affairs.     

Water Stress and N Fertilization Effects on Yield and Smut Disease Incidence in Corn (Zea mays L.)

A 2-year field experiment was conducted in sandy clay loam soil to quantify the single and combined effects of N fertilization and water stress (WS) treatments on yield and smut incidence in corn. The plants were supplied with two different N rates (225 and 300 kg ha⁻¹) and subjected to 2 weeks' water stress, imposed at vegetative (Vg), tasselling (Ta), silking (Si) and grain-filling (Gf) growth stages. In addition, a control treatment (Cr) was also included to allow the plants to grow under unstressed conditions. The plants were artificially infected two times with Ustilago maydis spores and smut severity was recorded. At harvest, grain yield (GY), total biomass (Tbm) and harvest index (HI) were determined in smut-free (0) and smutted plants (S). Results have shown that GY₀ and GY_s were markedly reduced when the plants were subjected to WS. The depressing effects of WS were, comparatively, high at Gf. intermediate at Ta and Si. and low at Vg growth stages. Smut index (SI) data revealed that severity was higher on plants stressed at Gf than those exposed to WS at Vg, Ta or Si stages. Considerable variations were detected on Tbm and HI of smut-free and smutted plants, indicating the detrimental effect of plant water deficit at Gf stage. The combined effect of WS and N on Tbm_s showed mixed results, ranging from positive response for stressed plants at Si and Gf to little response at Cr, Vg or Ta stages at higher N rate. Although the effect of WS exposure on RYL data was dominant at Gf, the rate of yield depression was relatively higher at Ta and Si than the other growth stages, because of water deficit effects. The results proved that N fertilization did not conclusively alleviate the depressing effect of WS on grain yield losses.     

Interference between red kidneybean (Phaseolus vulgaris L.) cultivars and redroot pigweed (Amaranthus retroflexus L.)

Field experiments were conducted in 2006 and 2007 to evaluate the competitive ability of bush type red kidneybean (RKB) (Phaseolus vulgaris L.) cultivars against redroot pigweed (Amaranthus retroflexus L.). Three cultivars of RKB (Akhtar, Sayyad and D81083) and five A. retroflexus densities (0, 4, 8, 16 and 32 plants m⁻²) were established in a factorial arrangement. A. retroflexus had a greater plant height and growth rate (GR) but a lower leaf area index (LAI) than RKB cultivars in almost all treatments. Higher densities of A. retroflexus increased LAI and GR but decreased yield of RKB cultivars. The cv. Sayyad and D81083 had the greatest and lowest LAI and GR, respectively, in competition with A. retroflexus. The maximum intercepted photosynthetically active radiation (PAR) at noon by A. retroflexus was 90.4 and 66.0% in competition with cv. D81083 and Sayyad, respectively. The seed yield and pod number per plant of RKB cultivars decreased severely with increasing A. retroflexus density. A. retroflexus seed number m⁻² was the highest and lowest in competition with cv. D81083 and Sayyad, respectively. The competitive ability of RKB cultivars was compared using parameters estimated through two-parameter yield loss-relative leaf area model. The relative ranking of the RKB cultivars examined for their competitiveness, supported by modeling results, was Sayyad > Akhtar > D81083.