Effect of plant density on the inflorescence production of stems and the distribution of flower production in potato

Summary A knowledge of the pattern of flowering and seed production is required for the development of large-scale field production of True Potato Seed (TPS). At the highland experimental station of the International Potato Center in Peru, data on flowering and seed production were collected from three cultivars planted at three densities. Main stems in which flowering was delayed ceased shoot growth at an earlier stage and produced fewer inflorescences. Inflorescences produced later had fewer flowers, a lower berry set and yielded less seed. Inflorescences flowering at the same time performed similarly, irrespective of their position on the plant. Increasing plant density resulted in cessation of shoot growth at an earlier stage and concentrated inflorescence and flower production at primary positions of early-flowering shoots. With cvs Renacimiento and Yungay a higher plant density increased the percentage of flowers produced in the first three weeks of the flowering period, but with cv. Atzimba the effect of plant density on the distribution of flower production was off-set by a slower stem development.     

Flowering and true seed production in potato (Solanum tuberosum L.). 1. Effects of inflorescence position,nitrogen treatment,and harvest date of berries

Summary Flowering and true seed production from different order inflorescences in potato (Solanum tuberosum L.) were evaluated in two experiments. The number of flowers per inflorescence, berry set, berry weight, number of seeds per berry and seed weight generally decreased from primary inflorescences to tertiary inflorescences and inflorescences on lateral stems. The possible relation with carbohydrate distribution is discussed. Quality of the seeds produced from the different orders of inflorescences was a function of seed size; larger seeds showed better germination, emergence and seedling growth. Late harvest of berries increased berry weight and number of seeds per berry from primary inflorescences. Application of additional nitrogen during the flowering period did not affect flowering or differences between inflorescence positions in seed production, but it significantly decreased the number of seeds per berry. The practical implications of these results for true seed production are discussed.     

Flowering and true seed production in potato (Solanum tuberosum L.). 2. Effects of stem density and pruning of lateral stems

Summary Field experiments were carried out to evaluate the effect of stem density and pruning of lateral stems on flowering and true seed production in potato (Solanum tuberosum L.). Increasing stem density reduced flowering, berry and seed production from every inflorescence in all cultivars. Increasing density increased the proportion of primary flowers in the total number of flowers per plant and reduced the proportion of flowers on lateral stems, but its effect on the quality of the seed production was small. Differences in total seed production were principally determined by differences in flowering. There was an interaction between stem density and cultivars for the number of flowers produced and on the yield of true seed per m². Pruning lateral stems enhanced flowering of the main stem and decreased the total number of flowers per plant, but it did not affect berry and seed production from main-stem inflorescences.     

Variability and regulation of the number of ovules, seeds and pods according to assimilate availability in winter oilseed rape (Brassica napus L.)

The number of pods per plant and the number of seeds per pod are the most variable yield components in winter oilseed rape (WOSR). Both the number of ovules per pod and the potential for the ovule to develop into a mature seed may depend on pod position in the plant architecture and time of appearance. The complex developmental pattern of WOSR makes it difficult to analyse. The objectives of this study were to investigate the variability of the following yield components (a) ovules/pod, (b) seeds/pod, and (c) pods/axis in relation to two explanatory variables. These two variables include (1) flower and inflorescence position and (2) time of pod appearance, linked to the effect of assimilate availability.Field experiments were conducted with the variety Mendel. Different trophic states were created by clipping the main stem or ramifications. The number and position of flowers that bloomed within the inflorescence were recorded based on observations every two to three days throughout the flowering season.On the control plants, for the main stem we observed that the number of ovules per pod decreased for a few ranks and then tended to increase and again to decrease at the end. On ramification R1 and R4, the number of ovules increased at first, and then remained constant with the pod rank. Furthermore, the number of ovules per pod remained constant along the inflorescence on the other ramifications and increased with ramifications from top to bottom. The number of seeds per pod did not vary with the pod rank at the basal positions on inflorescences and decreased afterwards along the inflorescence. The clipping of the main stem or ramifications increased the number of ovules per pod, seeds per pod and pods per axis. The number of ovules and seeds per pod did not vary with the time of pod appearance for the pods located at normalised rank 0.01-0.1. However, the number of ovules and seeds per pod can be impacted by the time of pod appearance on the plant scale. Thus, our results indicate that the amount of available assimilates was the primary determinant of pod and seed production during the flowering period. The distribution of resources was significantly affected by both the positions of pods within an inflorescence and the position of inflorescences within a plant.     

去枝、疏花对甘蓝型杂交油菜苏优3号千粒重及产量的影响

以杂交油菜苏优3号为材料，研究去枝、疏花处理对千粒重及单株产量的影响，结果表明，去枝，蔬花后，主轴，一次分枝和二次分枝的千粒重显著增加，角果宽度和长度亦增加，去枝后单株千粒重增加16．61％，疏花后单株千粒重增加14．05％，均达极显著水平，去枝后单株产量下降，下降幅度最高为9．77％，达极显著水平，每个花序疏花5朵，单株产量增加0．38％，增产不显著，疏花10朵以上则单株产量逐渐下降。     

受控环境下光周期对小麦生长发育、产量及营养品质的影响

为探讨受控生态生保系统(CELSS)中利用光周期调控提高植物能量利用效率的可能性,以红蓝LED(90%红+10%蓝)为光源,在开花前及开花后各设置12、16、20和24h四个光周期水平,形成16个处理,研究光周期对小麦生长发育、产量和营养品质的影响。结果表明,开花前光周期延长使小麦开花时间显著提前,特别是导致出苗到拔节和拔节到抽穗的天数显著减少。开花后光周期延长会缩短开花到成熟的时间,且开花前和开花后光周期对小麦生育期长度的影响相互独立。在开花前,短光周期有利于小麦营养器官的构建,增加株高、分蘖数、叶片数和营养器官干重,进而提高籽粒产量、收获指数和能效比。在开花后,长光周期提高了灌浆期叶片光合速率,促进籽粒中干物质积累,提高籽粒产量、收获指数和能效比。开花前短光周期的增产作用主要是因穗数和穗粒数增加,而开花后长光周期的增产作用主要是因粒重增加。在开花前后,延长光周期均导致籽粒淀粉含量增加和蛋白质含量减少。在开花前12h光照、开花后24h光照的处理下小麦产量和能量利用效率均最高,说明开花前短光周期结合开花后长光周期最有利于小麦高产和能量高效利用。     

Evaluation of seed production potential in white clover (Trifolium repens L. varietal improvement programmes

The components of actual and potential seed yield were examined in field experiments on a wide range of varieties of white clover (Trifolium repens L.). The factors affecting seed yield under conditions typical of management regimes used in the production of commercial seed crops were assessed in two experiments. In the first, carried out on spaced plants, considerable diferences are shown between six varieties across the range of leaf sizes in the distribution and profuseness of inflorescence production through the flowering season. In the second, carried out in plots, typical on-farm criteria were used to choose a single harvest date. Significant variation was found between varieties, including representatives of different leaf size categories, for seed yield components that include number of inflorescences m^?2, number of florets per inflorescence and harvestable seed weight. Large-leaved varieties tended to produce more seeds per floret and higher seed weights per inflorescence, whereas small-leaved varieties gave the highest number of inflorescences ^?2. However, the small-leaved variety AderDale, selected for strong peduncles, was exceptional, giving high values for all seed yield components. The impact of weather conditions on many seed yield components (e.g. total number of inflorescences) was demonstrated by the differences between the 2 years of the experiment. However, other characterstics, e.g. number of florets per inflorescence and number of seeds per floret, did not vary between years. Deviations from potential seed yield were assessed fromthe perspective of commerical seed production. The implications of these results for the production of white clover varieties with increased seed yields under UK conditions are discussed.     

The effects of nutrient supply on flowering and seed production in Poa annua

The effect of nutrient concentration on the reproductive development and seed yield of Poa annua was examined in a sand culture experiment. The nutrient concentration during the initial vegetative stage did not affect the time taken for double ridge formation by the main shoot but did influence the subsequent development of the inflorescence as did the post-initiation level of nutrients. At low nutrient levels flowering was inhibited in some individuals but at the higher concentrations inflorescence emergence was hastened, inflorescence size was increased and, in particular, the number of spikelets and hence the number of seeds per inflorescence was greatly increased. The mean weight of 100 seeds was unaffected by the nutrient concentration. The number of reproductive tillers per plant was increased by high nutrient supply but the proportion of dry weight allocated to root development was reduced.     

Post-flowering tillering in contrasting light environments of two New Zealand perennial ryegrass cultivars with different perennation strategies

Post-flowering tillering responses of 'Ellett' and 'Grasslands Ruanui' perennial ryegrass ( Lolium perenne L.) cultivars after inflorescence production were studied at INRA, Lusignan in France, at near ambient light (absence of light competition, control treatment) and under shading (low-light intensity and low red–far red ratio). A dense sward containing inflorescence bearing plants of both perennial ryegrass cultivars at ambient light was cut to a height of 50 mm above ground level after which the light treatments were imposed. Forty-five days later, data were collected on the number of tillers per plant, the number of new tillers per original tiller and the dry weight of vegetative and reproductive tillers. Regardless of light treatment, cv. 'Ellett' had fewer tillers per plant, higher weight per tiller and a higher proportion of reproductive tillers than did cv. 'Grasslands Ruanui'. Number of tillers per plant and number of new tillers per tiller were consistently reduced under shade compared with the control treatment for both cultivars. When shaded, weight of reproductive tillers of cvs 'Ellett' and 'Grasslands Ruanui' were 40% and 43%, respectively, less than the control, whereas vegetative tiller weight did not change. In addition, differences between cultivars in the tillering strategy after flowering seem to be unaffected by the light environment. Thus, field observations regarding tillering of cvs 'Ellett' and 'Grasslands Ruanui' were consistent with current results suggesting different grazing managements are needed after flowering to optimize the replacement of tillers for both cultivars.     

AN ASSESSMENT OF (2-CHLOROETHYL) TRIMETHYLAMMONIUM CHLORIDE AS A POTENTIAL AID TO GRASS-SEED PRODUCTION

The effects of (2–chloroethyl) trimethyIammonium chloride (CCC) on inflorescence production and culm length in seedlings of Aberystwyth S51 timothy ( Phleum pratense L.) are described. Concentrations of CCC ranging from molar to 0.01 molar were applied as a soil drench at a rate of 75 ml/sq. ft to plants at the 3rd, 6th or 8th leaf stage. All treatments reduced the culm length at heading, maximum effect being obtained from those given at the earliest growth stages. The number of heads per plant and the total head-length per plant increased with treatment, showing a maximum after molar treatments at the 6th or 8th leaf stages. Mean head-length remained relatively constant. The results are discussed in relation to seed production problems and the questions to be answered prior to field-scale treatment are outlined.     

Seed production in white clover (Trifolium repens L.). II. Effect of autumn defoliation on potential seed yield and seed yield components

A field experiment was conducted to assess the effect of autumn defoliation treatments on inflorescence production, potential seed yield and yield components of white clover cv Makibashiro. Between 10 July and 10 October 1992, white clover swards were subjected to one of three treatments: monthly cutting to 3–4 cm (4DEF), cutting to 3–4 cm on 10 August and 10 October (2DEF), and no cutting (control). The total numbers of inflorescences and the proportion of inflorescences in different development categories were counted throughout the period of seed crop development to determine the pattern of inflorescence development and optimum harvest date. There were consistent significant differences in inflorescence density between treatments. Plots which received the 2DEF treatment produced significantly more inflorescences than did the no-defoliation (control) and 4DEF-treatment plots. In this particular year the optimum harvest date (date at which the proportion of ripe inflorescences and potential seed yield was highest) was 26 July, approximately 30 d after peak flowering. Defoliation treatments had no effect on optimum harvest date. However, treatments differed in potential seed yield and ripe inflorescences on this date. The 2DEF treatment gave the highest potential seed yield because there were significantly more ripe inflorescences than either the contol or 4DEF plots. Control plots produced inflorescences with more florets than the other two defoliation treatments, but the differences were not always significant. Seed number per pod was higher in inflorescences obtained from previously defoliated plots than from control plots. The 1000-seed weight was significantly lower in inflorescences developed in 4DEF plots than those developed in 2DEF and control plots. The results are discussed in relation to the management of white clover seed crops and the importance of canopy structure and light intensity for seed production.     

硼钼锌对双低油菜华双4号籽粒发育进程中干物质累积的影响

通过水泥池小区试验，研究了B、Mo、Zn三种微量元素对甘蓝型油菜双低品种华双4号角果发育进程中干物质累积过程的影响。结果表明：硼、锌缺乏阻碍了主茎和第一次分枝角果皮干物质向籽粒的转运，进而影响籽粒干重的增加；三种微肥以及硼、锌配施利于角果皮干物质向籽粒的转移，促进籽粒增重。华双4号主茎角果皮干重在开花后43d达最大值，第一次分枝角果皮干重在开花后38d达最大值，主茎籽粒干重在开花后53d达最大值，第一次分枝籽粒干重在开花后49d达最大值。各处理主茎籽粒干重和粒壳比在花后38d出现明显差异，而第一次分枝的籽粒干重和粒壳比在花后33d开始出现明显差异。硼钼锌配合施用有利于油菜籽增产，对产量影响顺序为，完全处理（NPKBMoZn）>-Zn（NPKBMo配合）>-B（NPKZnMo配合）>-Mo（NPKBZn配合）>CK（NPK）。     

根瘤菌对大豆根际土壤微生物及大豆农艺性状的影响

为研究施用根瘤菌条件下,大豆不同生育期土壤中微生物数量的动态变化及其对大豆农艺性状的影响,于大豆苗期、花期、结荚期、鼓粒期、成熟期分别对大豆根际土壤细菌、真菌、放线菌采用平板计数法进行数量测定;于大豆成熟期对大豆农艺性状及产量进行测定。结果表明:大豆根际土壤微生物数目随大豆生育期不同而发生变化。与对照相比,根瘤菌的施用均增加了除花期外各时期土壤中细菌的数量,在结荚期、鼓粒期和成熟期,增加了土壤真菌数量,在结荚期和成熟期增加了土壤放线菌数量;根瘤菌的施用增加了大豆的株高、主茎节数、单株荚数和单株粒数,且有效增加了大豆产量,与对照相比增产19.44%。     

Yield and seed quality of Plantago ovata and Nigella sativa under different irrigation treatments

Employing locally adapted plants together with irrigation scheduling based on developmental stage in semi-arid and arid regions may provide an opportunity to optimize irrigation efficiency, and water savings in regions where water resources are limited. To investigate this water saving potential, the final seed yield and quality of two local plant species were investigated under water deficit conditions over two growing seasons (2003, 2004) in the northeast of Iran. In this study, black cumin (Nigella sativa L.) which is used locally as an anti-microbial and isabgol (Plantago ovata Forsk.) which is used as an anti-diabetic plant were exposed to four different irrigation regimes. Weekly irrigation was the control, and the three treatments based on developmental stage for both species were termination of irrigation at blooming (folded flowers), flowering, and seed formation. Isabgol seed yield was lower for all of the water deficit treatments compared to control, but black cumin showed tolerance to water deficit except when irrigation was terminated at seed formation. The lowest seed yield was obtained when irrigation was stopped at the blooming stage, and the number of seeds per plant was the main yield component affected. One thousand seed weight for both species was relatively stable across all irrigation treatments, and higher seed yield was consistent with higher straw yield and plant height. Our results did not show any reduction in oil concentration for black cumin or mucilage percentage for isabgol across all water deficit treatments.     

Effect of plant density on stolon growth and development of contrasting white clover (Trifolium repens) varieties and its influence on the components of seed yield

Plants of two contrasting white clover varieties (cv. Aberystwyth S184 and Olwen) were planted in the field in spring in each of 2 years at four densities (9, 25, 49 and 100 plants m⁻²) in 1-m² plots. The effect of plant density on stolon growth and development and the components of seed yield was subsequently measured.
Stolon growth and development was influenced by plant density, variety and year. At low plant densities both white clover varieties produced longer primary stolons than at higher densities. Plant density, however, had no significant effect on the number of inflorescences at harvest. At the high stolon densities there were significantly fewer reproductive nodes per primary stolon than at the lower plant densities. Plant density did not significantly affect any other seed yield components, but the number of inflorescences at harvest, florets per inflorescence, seed set per floret and 1000-seed weight were all significantly influenced by both variety and year.
The relationship between the vegetative and reproductive growth of white clover is discussed in relation to plant density, variety and climate and the possible role of defoliation managements on inflorescence development.     

Seed production in grassland species: Morpho‐biological determinants in a species‐rich semi‐natural grassland

Studying the seed production of herbaceous species can help to conserve grassland habitats and re‐create new high‐value grassland surfaces. Studies on grassland seed production have focused mainly on individual species and traits, without characterizing their relative importance at the plant community level. The aim of this study was to investigate the entire seed production process of the main species in a temperate grassland. Fertile shoots (FS) of twenty‐nine grasses and forbs were collected over 4 years and analysed for sixteen traits that determine inflorescence size, seed production and seed quality. The per cent viability played a predominant role in determining the total production of viable seeds. Forbs showed a range of reproductive strategies, including variable distribution of flowers among growth periods, number of inflorescences per FS and relationship between seed size and FS density in the grassland. The flower production for grasses was concentrated in the first growth period, but this limitation was mitigated by a higher seed dormancy. The number of viable seeds per FS and seed size were important components of the reproductive strategy of forbs, with heavy‐seeded species being characterised by high individual densities in the community, but producing few seeds per FS. Light‐seeded species showed an opposite pattern. The results suggest that when using seeds from semi‐natural grasslands for ecological restoration, special attention should be paid to the seed amount, germinability and viability of forbs, as they seem to depend more on seed reproduction and have a lower ovule to seed transformation efficiency.     

不同生育期施用"奥普尔"对夏大豆生长发育的影响

用奥普尔液肥处理土壤，可提高大豆出苗率９．１％。除鼓粒期外，其余生育期使用该液肥，株高降低，分枝数增加，株英数增加百粒重降低；而鼓粒期施用，株高、分枝数没有变化，株英数和百粒重增加，综合效果，大豆施用奥普尔液肥，株粒数增加，产量提高，经济效益提高。以上土壤处理和花期喷施效果最好，增产率分别达１１．８％和９．６％；两次是复加施用，增产率达１３．６％，投放产出比达１：５．３。     

Photoperiod sensitivity after flowering and seed number determination in indeterminate soybean cultivars

Seed and pod numbers are the main yield components in soybean (Glycine max (L.) Merrill). They are related to canopy photosynthesis during a critical period, occurring between the R1 (beginning of flowering) and R6 (full seed) stages. We investigated the relationship between the duration of the critical period and the number of seeds produced. Response to photoperiod during post-flowering stages was evaluated in indeterminate soybean cultivars from maturity groups (MG) IV and V. The study was conducted under field conditions with two sowing dates (normal and late). Plants were grown under natural photoperiod throughout the experiment or exposed, from the R3 stage (beginning pod) onwards, to artificially extended regimes of 2 h longer than natural daylength. Duration of the R3–R6 period increased in response to the extension of photoperiod, and cultivars of MG V exhibited a stronger sensitivity to photoperiod than those of MG IV. Exposure to long photoperiods promoted node production, mainly in branches, and increased node fertility. Within each sowing date, the increased duration of R3–R6 under longer photoperiods was corresponded with increments in pod and seed number. Seed number was related to the duration of R3–R6, particularly when the length of the period was corrected for temperature differences between treatments. Seed number was also related to the integral of solar radiation during R3–R6. The possibility of using sensitivity to photoperiod after flowering as a criterion for increasing yields through increasing seed number are discussed.     

氮肥管理与根瘤菌接种模式对花生生长、氮吸收利用及产量的影响

为探求豫南砂姜黑土区花生高产和氮肥高效利用栽培技术，采用大田试验，研究了氮肥管理与不同根瘤菌接种模式（拌种或土施）对花生生长、氮吸收利用及产量的影响。结果表明，施氮提高了花生叶片SPAD值，有效促进花生生长，显著增加了氮利用率和荚果产量。两种根瘤菌接种模式下，不同氮肥管理中均以50%N基施+50%N开花期追施和100%N基施处理的第一侧枝长、总分枝数、单株饱果数、单株饱果重和百果重、氮利用率和产量显著高于50%N开花期追施+50%N结荚期追施处理，说明要实现花生高产和氮素高效利用需在花生生育前期施用一定量的氮肥。比较根瘤菌拌种和土施2种接种模式，以根瘤菌拌种配施氮肥对花生的增产效果较好，但与根瘤菌土施配施氮肥处理间差异不显著。综合分析，在豫南砂姜黑土区，花生种植采用氮肥50%基施、50%开花期追施配合根瘤菌拌种的模式增产效果最好，氮肥利用效率最高。     

赤霉素及烯效唑对大豆形态、光合生理及产量的影响

为了解赤霉素ＧＡ３和烯效唑的壮苗效果,采用ＧＡ３和烯效唑浸种处理大豆种子,调查大豆茎秆、节长、叶柄、叶片光合特性及产量的变化。两年结果显示,ＧＡ３ 和烯效唑对大豆株高有调控作用,但具有时效性。苗期,ＧＡ３处理增加株高,烯效唑抑制株高;盛花期、结荚期和鼓粒期处理与对照之间株高无显著差异;收获期ＧＡ３处理降低了第１、３、１０、１２、１３、１４节节长,从而显著降低大豆株高,烯效唑降低第１节节长,不影响株高。ＧＡ３和烯效唑 浸种处理均增加大豆茎粗,增强大豆抗倒伏性。ＧＡ３处理降低了８～１０节叶柄长度、增加了１４～１８节叶柄长度;烯效唑增加７～１２节叶柄长度。两种调节剂从节长和叶柄两个方面改变了大豆冠层结构,叶柄长度的变化量与同节位的产量贡献率的变化量显著相关,相关系数为０．６２２和０．５８５,Ｐ＜０．０５。烯效唑浸种处理能够增加７ｄ、１４ｄ叶绿素含量,１４ｄ光合速率,显著提高单株粒数、单株荚数和产量,两年平均增产１５．１４％。说明烯效唑处理可能通过改变大豆冠层结构和光合性质影响大豆产量。