Simulating growth,development, and yield of tillering pearl millet: I. Leaf area profiles on main shoots and tillers

Pearl millet (Pennisteum americanum L.) is an essential crop in farming systems of the dry areas of the semi-arid tropics and its tillering habit is an important adaptive feature. This is the first paper in a series aiming at developing and validating a pearl millet simulation model that recognises tillers as functional entities, analogous to intercrops. The objective of this paper is to quantify the effects of total leaf number per axis (TLN), cultivar, plant density and axis number on parameters that are used to simulate potential leaf area per plant. Four cultivars with different phenology and tillering habit were grown under well-watered and well-fertilised conditions at two locations in India, covering a range of daylengths and plant densities. For selected plants, the area of fully expanded leaves was measured non-destructively. A bell-shaped function adequately described the relationship between individual leaf area and leaf position on an axis. Its shape was determined by the position (X₀) and area (Y₀) of the largest leaf and by the breadth and skewness of the leaf area profile curve. TLN affected all four parameters, although the association with Y₀ was weak. Cultivar only affected Y₀, suggesting that parameterising new cultivars is straightforward. The observed density effect confirmed that competition for light between axes started during stem elongation. The results highlighted the consistent differences between leaf area profiles of main shoots and tillers. For a high-tillering crop like pearl millet, modelling leaf area dynamics through individual leaves is justified, as this approach can potentially deal with cultivar and environmental effects on tillering.     

The effect of nitrogen fertilization upon the herbage production of tall fescue swards continuously grazed with sheep. 1. Herbage growth dynamics

The effect of level of nitrogen application upon the dynamics of herbage growth in a continuously grazed sward of tall fescue was investigated during two successive years. In order to obtain a large range of sward structural conditions, the experiments were carried out with two contrasting cultivars: cv. Clarìne and cv. Barcel, and, in Year 2, with two different sward heights or leaf area indices (LAIs). During each of five experimental periods (2-3 weeks), swards received either optimum (N2) or deficient (N1) N applications, were maintained at their target LAI, and leaf growth was measured on labelled tillers. With continuously defoliated tillers, N-shortage had only a small effect on the leaf elongation rate compared with tillers protected by cages. The leaf production per tiller was only slightly reduced by N shortage, and it was mainly by the means of a reduction in tiller density that the N deficiency resulted in reduced herbage growth per hectare. These results indicate that, in continuously grazed swards, in contrast with results previously found in intermittently defoliated swards, leaf elongation is not the only important component of difference in herbage growth and that the promotion of tillering rate is an additional pathway for N response in such management regimes.     

行距对两个不同类型水稻品种冠层结构与产量的影响

 以寒地粳稻龙粳20(多蘖 弯穗型)和龙粳21(少蘖 半直立穗型)为试材,研究了行距对两个不同类型水稻品种冠层结构、形态和产量的影响。结果表明,行距与两种类型水稻成穗率呈先降后升的二次回归关系,与分蘖末期叶面积指数和单位面积最大茎蘖数呈先升后降的二次回归关系。行距对龙粳20一次枝梗的影响大于二次枝梗,而龙粳21则相反;行距与参试品种的二次枝梗结实率和穗结实率均呈负相关,其中与龙粳20二次枝梗结实率呈极显著负相关。行距与龙粳20产量呈正相关,但相关不显著,与龙粳21的产量呈极显著负相关。多蘖 弯穗型品种的株型性状更易受到行距的影响,其中行距与龙粳20的剑叶长、剑叶宽、倒1节间长、倒2节间长和穗长均呈显著或极显著正相关,而与龙粳21的各株型性状相关均不显著。较宽行距有利于多蘖 弯穗型品种穗、茎、叶干物质积累和产量的形成,龙粳20的最佳行距处理为30 cm,而少蘖 半直立穗型品种龙粳21,窄行距更佳,最佳行距为21 cm。分析认为宽行距移栽有利于改善多蘖 弯穗型品种的群体生态环境,窄行距有利于提高少蘖 半直立穗型品种的空间利用。     

Physio-Morphological Characters of F1 Hybrids of Rice (Oryza sativa L.) in Japonica-Indica Crosses: II. Heterosis for leaf area and dry matter accumulation

Summary

A pot experiment was conducted to investigate the heterosis for morphological characters and to examine the relationship among some characters at active tillering, flowering and dough ripe stages of 12 Fj hybrids from crosses between japonica and indica rice. Heterosis for plant height, number of tillers, green leaf area and dry matter accumulation per plant was positive at all stages. The intensity of heterosis was higher at the active tillering stage for number of tillers, leaf area and dry matter accumulation per plant. A significant positive relationship was found between tiller number and leaf area per plant at active tillering and flowering stages. Significant positive relationships between leaf area and dry matter accumulation, and between tiller number and dry matter accumulation per plant were observed at all stages. A significant positive relationship was found between leaf area per plant at an early stage and dry matter accumulation per plant at a later stage, suggesting that early development of leaf area is an important factor for higher dry matter accumulation in 1 hybrids. Although heterosis for percent dead leaf blade was positive at the flowering stage due to early leaf senescence in some Fx hybrids, a larger leaf area was also found in Fx hybrids at this stage and leaves of Fx hybrids remained green longer compared to parent cultivars up to the dough ripe stage.     

基因型和氮肥对冬小麦叶片形态建成和分蘖的影响

于１９９８～１９９９ 年在浙江大学华家池校区实验农场进行了田间试验,研究基因型和环境对小麦叶片形态建成和分蘖的影响。试验由３ 个基因型（浙麦１ 号,ＺＡＵ９７－２,扬麦５ 号）和３ 种氮肥水平（０,１２０,２４０ ｋｇ／ｈｍ ２）的９ 种组合处理组成。主茎各叶片长度,除第１、９ 和１０ 外,基因型之间差异显著,叶片宽度随叶位高度而增加,各叶片面积的变化与叶长基本一致,第１ 至５ 叶依次增加,第６ 叶明显减小,第７ 叶又逐渐递增;单株分蘖数和分蘖消长动态因基因型而异。氮对叶片形态有明显影响,但除旗叶外,Ｎ１２０ 和Ｎ２４０ 两种氮水平之间叶长无显著差异。氮对分蘖的发生影响较小,但能显著促进其后的生长。基因型和氮肥对叶片形态和分蘖的影响存在着一定的互作效应。     

两个杂交粳稻组合超高产生长特性的研究

 : 将两个杂交粳稻组合（陵香优18和常优1号）于大田条件下种植,对超高产（产量＞12.0 t/hm2）田块的水稻物质生产和产量形成生长特性进行了分析。结果表明,与高产栽培（CK, 10.5～11.0 t/hm2）水稻相比,超高产栽培水稻穗数、每穗粒数显著高于CK,结实率和千粒重略高于CK,但差异不显著;超高产栽培水稻二次枝梗数、二次枝梗总粒数显著高于CK;有效分蘖临界叶龄期之前,超高产栽培条件下水稻生长比CK快,在有效分蘖临界叶龄期茎蘖数达到预期的穗数,叶面积指数、光合势、干物质积累和群体生长率较CK大;有效分蘖临界叶龄期至拔节期,超高产栽培条件下水稻生长平稳,无效分蘖发生少,高峰苗低,叶面积指数、光合势、干物质积累和群体生长率较CK小;拔节以后,超高产栽培条件下水稻茎蘖数下降平缓,成穗率高,叶面积指数、光合势、干物质积累和群体生长率较CK高,尤其是抽穗以后,超高产栽培条件下水稻具有明显的生长优势,叶面积指数、光合势、干物质积累和群体生长率均极显著高于CK。     

秧苗密度和施氮量对超高产杂交籼稻秧苗素质的影响

 2007年在云南省永胜县涛源乡水稻特殊高产生态区,利用杂交籼稻组合协优107,设计了氮肥处理（10.3、207、31.0和41.4 g/m2N）和秧苗密度处理（353、706、1059和1412苗/m2）双因子试验,旨在探讨施氮水平、秧苗密度和秧龄对超高产杂交籼稻秧苗素质的影响。结果表明：1)秧苗密度降低或施氮量增加,均降低出叶所需的有效积温,加快秧苗的出叶,且秧苗密度的效应更显著;2)高密度或低氮条件下,秧苗单株带蘖数随着秧龄的增加有减少的趋势;而在高氮或低密度条件下,秧苗单株带蘖数在播种后27 d（7叶期）内呈增加趋势,之后进入分蘖衰减期;3)施氮对秧苗新分蘖的发生和大分蘖保持、苗床叶面积指数的增大、单株干质量的增加以及植株含氮量的提高均有正效应;4)秧苗密度对秧苗新分蘖的发生和大分蘖保持、单株干质量的增加均有负效应,并比氮效应明显;对植株含氮量的提高也有一定的负效应;对苗床叶面积指数的增大有正效应。     

SOME EFFECTS OF GRAZING MANAGEMENT ON THE YIELD AND ITS COMPONENTS OF SOME PASTURE GRASSES

A study was made to determine the effects of grazing to a height of 1 in. when the swards reached heights of 3 and 9 in. on the dry matter production, LAI, tillering and rate of leaf production of new and old tillers in the spring–summer and autumn–winter seasons of 3 pasture species growing in association with white and red clovers. In both seasons the herbage yield under 9–1 management was higher than that under 3–1 and was significantly greater in the spring-summer season. Differences in DM production between cocksfoot, tall fescue and Ariki ryegrass failed to reach significance.
Light utilization under the 2 management systems was considered to be inefficient. In the autumn-winter period there was a linear relationship between the LAI and DM production in all treatments.
The rate of leaf production per tiller was significantly higher in cocksfoot than in ryegrass and tall fescue in both seasons.
New tillers had a significantly higher rate of leaf production than old tillers in the spring-summer period, but not in autumn-winter. The numbers of grass tillers and rooted nodes of clover were significantly higher under 3–1 than under 9–1 and were influenced by season.     

返青期断根对秸秆覆盖冬小麦产量及叶片光合特性的影响

为了解返青期断根对黄土高原旱地保护性耕作下小麦产量形成及水分利用的调控作用,在陕西长武县开展旱地秸秆覆盖条件下冬小麦返青期断根试验,分析了返青期断根对冬小麦籽粒产量、地上部生物量、收获指数、产量构成三要素、拔节期群体数量、生育期耗水量、水分利用效率、花后旗叶光合特性及衰老特性的影响。结果表明,返青期断根对冬小麦地上部生物量、穗数、粒重和生育期耗水量没有显著影响。与CK(不断根)相比,返青期断根后冬小麦拔节期总茎数减少了11.9%,开花期叶面积指数、花后旗叶叶绿素含量、光合速率和蒸腾速率提高,分蘖成穗率、穗粒数、籽粒产量、收获指数和水分利用效率分别增加了14.1%、10.5%、8.2%、10.4%、17.5%和20.4%。这说明返青期断根可促进秸秆覆盖条件下冬小麦分蘖成穗,增加花后旗叶光合作用,改善穗部结实特性,提高籽粒产量和水分高效利用。     

Leaf development of spring wheat cultivars in an irrigated heat-stressed environment

Wheat (Triticum aestivum L.) is expanding into lower latitudes of the Nile Valley Region, where maximum air temperature can reach 38–40°C during the short growing season. Genotype and environment, particularly temperature, affect the rate of leaf appearance. Field experiments were conducted at the Gezira Research Station, Wad Medani, Sudan in 1992–94. The study aimed to determine the effect of high temperature (by manipulating sowing dates) on leaf and tiller appearance and growth of nine spring wheat cultivars. Linear response was found between rate of leaf appearance and thermal time and it was faster before double-ridge stage than after double ridge. Phyllochron ranged between 99°C d and 122°C d. Differences in phyllochron interval (PI) were pronounced among cultivars and early-maturing cultivars had faster leaf appearance compared with late-maturing ones. Mean final leaf number on the main stem ranged from 8.1 to 12.2 and it was highly correlated with thermal time from sowing to double ridge stage (r=0.71**). Genetic constitution of cultivars had larger effect on number of leaves per main-stem than temperature. Tillers were initiated at leaf stage 2.9 and cultivars differed in their tillering capacity and only 1.5–2.0 reproductive tillers per plant were produced. About 810°C d were needed to produce tillers 1 and 2 and about 1140°C d for tillers 3 and 4. Leaf senescence started at leaf stage 6.1 for cv. Wadi El Neil and 4.2 for Debeira. Cultivars sown late exhibited delayed senescence of their leaves. High temperature accelerated maturity and the cultivars suited for the irrigated tropical environment were found to be early-sown late-maturing types.     

Response of pearl millet to grain sorghum environments

Increasing awareness of drought tolerance in pearl millet [Pennisetum americanum (L.) Leeke.] has stimulated research into pearl millet as a potential U.S. crop. Objectives of this study were to compare yield and yield components of pearl millet and grain sorghum [Sorghum bicolor (L.) Moench] and evaluate pearl millet response to a range of grain sorghum environments.Yield and yield component comparisons were made using 24 millet hybrids and six grain sorghum hybrids at seven Kansas locations, from 1980 to 1982. To compare pearl millet production in grain sorghum environments, millet hybrid mean yields were regressed on sorghum location means. A desirable millet hybrid would have a high yield and a regression coefficient not significantly different from 1.0.Average grain sorghum yields were greater than millet yields in all three years. Millet hybrid yields ranged from 350 to 5400 kg ha⁻¹. Over all locations and years, millet yield averaged 63% of sorghum yield.In unfavorable environments, pearl millet yield and response to changing environments were not significantly different from those of grain sorghum. As environmental conditions improved, sorghum significantly yielded more than millet. Lower millet yields could be attributed to significantly smaller seed size and head sterility. The small seed also reduced plant establishment; however millet's tillering ability compensated for reduced population.     

稀植条件下杂交稻分蘖成穗规律和穗粒结构研究

研究了19.5,13.5和7.5穴/m2 3个种植密度下杂交稻组合中优6号和两优培九不同时期的分蘖成穗规律和穗粒结构.结果表明,稀植促进分蘖发生,并导致最高分蘖期和有效分蘖期延迟,13.5和7.5穴/m2比19.5穴/m2的最高分蘖期分别推迟7和14 d;随种植密度下降,中后期发生的分蘖在茎蘖数中的比例提高,相应成穗率也提高;早期分蘖所成的穗与后期分蘖所成穗的每穗粒数差异较大,结实率差异较小,两者的产量差异主要由穗粒数差异引起;随种植密度下降,分蘖力较弱的组合产量显著下降,而分蘖力较强的组合产量没有差异.     

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.     

The influence of light and temperature during winter on growth and death in simulated swards of Lolium perenne

Two growth experiments were carried out in January-March 1978 in which simulated swards of perennial ryegrass were (1) heated by soil warming cables to give soil surface temperatures of approx. 7·5-9·C above ambient temperature, (2) shaded with netting to reduce light levels by approx. 50%, or (3) both heated and shaded.
Heating alone increased leaf appearance, death, extension, lamina size, leaf area index (LAI), tillering (month 1)and whole plant weight (month 2) and reduced stubble water-soluble carbohydrates and specific leaf weight (SLW).
Shading alone increased leaf extension, lamina size and LAI but to a lesser extent than did heating. Shading decreased SLW, leaf death rate, tillering (month 2), stubble carbohydrates and whole plant weight, but not herbage weight.
The effects of heating plus shading were similar to those of heating alone, except that the increases in leaf size, extension and LAI were even greater, and shoot bases and roots had low or negative growth rates.
In general the heating treatments caused a rapid turnover of leaf material, but net herbage growth was relatively insensitive. It is concluded that (1) temperature rather than light was limiting whole plant growth, especially from mid-February to mid-March and (2) mild, dull weather in winter is likely to induce tiller death associated with reduced investment in carbohydrate reserves.     

减少追氮量对弱筋小麦品种农艺性状和生理特性的影响

为给小麦绿色高效生产提供参考,以弱筋小麦品种扬麦24为材料,在常规施氮量225kg· hm-2、基施氮肥占50％的基础上,于分蘖期、拔节期和孕穗期分别减少追氮量,共设M5122、M5050、M5040、M5030、M3230和M5000六个施氮模式(M后面的4个数字分别代表基施氮肥以及分蘖期、拔节期、孕穗期追施氮肥的比...     

不同时期弱光胁迫对晚稻不同耐弱光品种源库特征及叶片保护酶活性的影响

目的 本研究旨在明确弱光胁迫下不同弱光耐性品种在源库特征及叶片保护酶活性变化方面的差异,揭示其耐弱光胁迫的机制,为双季稻高产稳产新品种的选育及抗逆栽培提供理论指导。方法 以2个对弱光胁迫耐性存在显著差异的晚稻品种为材料,通过设置不同时期的遮光处理,研究弱光胁迫时期对晚稻不同耐性品种的源库特征及叶片保护酶活性的影响。结果 结果表明,不同时期弱光胁迫对晚稻生长有重要影响,分蘖期弱光胁迫下晚稻分蘖数、每穗粒数及总颖花量减少,叶面积下降,产量降低;幼穗分化期弱光胁迫下晚稻分蘖数和每穗粒数减少,总颖花量、叶面积、结实率均下降,产量降低;灌浆期弱光胁迫下水稻叶片净同化率降低,结实率和千粒重下降,产量降低。不同时期弱光胁迫对晚稻产量的影响表现为灌浆期>幼穗分化期>分蘖期。结论 耐弱光胁迫型品种能通过增加叶片的长宽度减少叶面积的下降,叶片含氮量保持相对稳定,叶片中SOD、CAT等保护酶活性保持在较高水平,POD活性保持相对稳定,叶片净同化率下降幅度小,在弱光胁迫下实现“强源”,减产率相对较低。弱光胁迫下具有较强的叶面积补偿能力和适宜氮含量以及较高的保护酶活性是水稻耐弱光胁迫的重要机制。     

Soil moisture and growth of contrasting varieties of Lolium, Dactylis and Festuca species

Varieties of Italian, perennial and Italian × perennial ryegrasses, tall fescue and cocksfoot were used to determine the effects of soil moisture on grass growth. Weather conditions were monitored and herbage accumulation, leaf extension rate, leaf appearance rate and tillering were recorded under natural (control), covered and irrigated treatments.
Water deficit reduced crop growth rate in the spring and drought was the major factor influencing crop growth rates in all varieties during the summer. The ryegrasses appeared most sensitive to drought, and particularly poor recovery growth was exhibited by the Italian ryegrass RvP and the hybrid ryegrass Snowdon.
Leaf extension rate and leaf appearance rate were both reduced by increasing soil water deficit. Herbage accumulation was increased by irrigation when potential soil water deficits were greater than 100 mm. When water deficits were large, irrigation increased leaf extension more than leaf appearance or tiller number. Increasing moisture deficit had a greater effect upon tiller number than on leaf extension.     

Effects of enhanced ultraviolet-B radiation on crop structure,growth and yield components of spring wheat under field conditions

Spring wheat (Triticum aestivum) was grown in the field for two consecutive seasons under ambient and supplemental levels of ultraviolet-B (UV-B, 280–315 nm) radiation to determine the potential for alterations in community structure, developmental stages, growth and yield components. The supplemental UV-B radiation simulated depletions of 12, 20, or 25% stratospheric ozone. Spring wheat is a potentially UV-B sensitive species, showing the greatest sensitivity to UV-B radiation at 5.31 kJ m⁻². Delays in development and decrease in plant height were observed at early tillering stage under UV-B treatment, and slowly exacerbated during further development. UV-B radiation changed crop structure, by decreasing the total number of tillers produced and increasing dead shoot number, resulted in fewer head-bearing shoots at ripening stage, and decreased biomass and yield. UV-B radiation decreased the area of the last leaf and leaf area index, but increased specific leaf weight. UV-B radiation inhibited biomass accumulation and altered the patterns of biomass partitioning; these effects might be correlated with yield. Decreases in yield were the result of significant reductions in spike number, grain number per spike and thousand grain weight under UV-B. Generally, the effects of UV-B radiation on developmental stages and crop structure were the most important, they might change the other characteristics of spring wheat crop. The responses of spring wheat crop to enhanced UV-B radiation were assessed, decreases in some crop characteristics caused by a 10 or 20% global ozone depletion were predicted. Ozone depletion had the greatest decrease in yield and the least reduction in plant height.     

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.     

Mixed Planting with Legumes Modified the Water Source and Water Use of Pearl Millet

Abstract

In semi-arid areas, pearl millet is an important staple food crop that is traditionally intercropped with cowpea. This study evaluated the water competition between pearl millet and cowpea using deuterated water. At vegetative stage, pearl millet biomass production was lower in the pearl millet-cowpea (PM-CP) combination than in the pearl millet-pigeon pea (PM-PP) and pearl millet-bambara nut (PM-BN) combinations. PM-CP used more water than PM-PP and PM-BN under well-watered conditions; however, all combinations used similar amounts of water under dry conditions. The biomass production, photosynthetic rates, transpiration rates, and midday leaf water potential of pearl millet at early flowering stage were not significantly reduced by mixed planting with cowpea sown two weeks later as compared with single planted pearl millet. When pearl millet and cowpea were sown at the same time, mix planting significantly increased the recovery rates of recently irrigated heavy water in pearl millet, but not in cowpea in both vegetative and early flowering stages. Midday leaf water potential and transpiration rates in pearl millet were lowered by mixed planting but those in cowpea were not. These indicate that the water source of pearl millet is shifted to the recently irrigated and easily accessible water. By contrast, when cowpea was sown two weeks later than pearl millet, this trend was not observed. These results provide new evidence on water competition in the PM-CP intercropping system; cowpea has higher ability to acquire existing soil water than pearl millet when both crops are sown at the same time.