Reduced Tillering Spring Wheats for Heavy Textured Soils in a Semi-arid Mediterranean Environment

Low tillering lines of spring wheat ( Triticum aestivum L.), were evaluated for their ability to conform to a high yielding ideotype in a dryland environment with spring drought. The ideotype was based on a concept of saving water as a result of reduced canopy development before anthesis; this should improve moisture supply for grain filling, thus reducing the effect of drought.
Five genotypes were compared under two nitrogen (N) levels, and at similar plant densities, at a site in the drier wheatbelt area of southwestern Australia. The genotypes formed three tillering groups based on the maximum number of culms produced: a free tillering group (G1), which included the standard cultivar Gamenya , with 4.3 culms per plant, an intermediate tillering group (G2) with 3.2 culms per plant, and a low ullenng group (G3) with 2.4 culms per plant.
Leaf area indices (LAI) were strongly affected by N but this was not reflected in total water use and biological yield. However, water was prematurely depleted before anthesis as a result of rapid early leaf development in response to N, and this reduced grain yield. Reduced tillering produced no significant increase in gram yield over the controls; fewer tillers per plant failed to suppress LAI development and water-use before anthesis because of a compensating increase in LAI; this resulted from a greater leaf size in the reduced tillering lines. Hence the low tillering lines did not fully conform to the requirements of the ideotype.
The development of low tillering lines is seen as a significant advance towards the ideotype; with yields comparable to commercial cultivars grown in the region, their performance indicates a potential for substantially higher yields if compensating increases in leaf development can be suppressed.     

Rapid Assessment of Specific Leaf Area and Leaf Nitrogen in Peanut (Arachis hypogaea L.) using a Chlorophyll Meter

The present study investigates the potential use of a hand-held portable SPAD chlorophyll meter for rapid assessment of specific leaf area (SLA) and specific leaf nitrogen (SLN), which are surrogate measures of transpiration efficiency (TE) in peanut ( Arachis hypogaea L.). The effects of sampling (leaf position, time of sampling and leaf water status) and climatic factors (solar radiation and vapour pressure deficit, VPD) on SLA and SPAD chlorophyll meter reading (SCMR) were studied in a range of peanut genotypes grown under field and greenhouse conditions. The correlation between SLA and SCMR was significant (r=−0.77, P < 0.01) for the second leaf from the apex but the correlation declined for leaves sampled from lower nodal positions. The diurnal fluctuation in SLA ranged from −20 % to +10 %, whereas SCMR was relatively unaffected by these diurnal changes. Solar radiation and VPD during the sampling period had a significant influence on the relationship between SLA and SCMR, largely through their effects on SLA. However, standardization of SLA for these environmental factors significantly improved the relationship between SLA and SCMR from −0.50 to −0.80 (P < 0.01), suggesting that, when protocols for leaf sampling and SLA measurements are followed, SCMR can be a surrogate measure of SLA. There were significant relationships between SLN and SCMR (r=0.84, P < 0.01) and SLN and SLA (r=−0.81, P < 0.01). These significant interrelationships amongst SLA, SLN and SCMR suggested that SCMR could be used as a reliable and rapid measure to identify genotypes with low SLA or high SLN (and hence high TE) in peanut.     

SPAD readings and associated leaf traits in durum wheat, barley and triticale cultivars

SPAD readings may represent a useful screening criterion in breeding programs aimed at increasing the rate and duration of leaf photosynthesis. A two-year trial was conducted on 17 cultivars of durum wheat, 8 of triticale and 18 of barley at two experiment stations in Sardinia, Italy, to evaluate the existence of genetic variation for SPAD readings, and to quantify the genetic associations between SPAD readings, area per leaf blade (LA), specific leaf area (SLA), leaf nitrogen concentration (LNC) and leaf nitrogen per unit of leaf surface (LN) in the period between beginning of tillering and flag leaf appearance. Plants were grown at sufficient nitrogen fertilization. The average SPAD reading of barley was 9–10 units lower than that of durum wheat and triticale. The combined ANOVA indicated that, in all the three species, the genotype by environment interaction variance associated with SPAD readings was lower than the genetic variance. In durum wheat and barley, SPAD readings exhibited a greater genetic variance in comparison with LNC, LN and SLA. In durum wheat and triticale, SPAD readings were genetically correlated with LN and SLA. Durum wheat differed from triticale because its genetic variation in SLA was not associated with LA. A screening based on both SPAD readings and LA values should identify lines with good photosynthetic machinery that is not associated with low area per leaf blade. This revised version was published online in July 2006 with corrections to the Cover Date.     

栽培稻叶结构、水分生理与抗旱性关系研究

摘 要：增强栽培稻品种的抗旱性是稻作节水生产的重要途径。稻作种质资源抗旱相关指标的研究是改良稻作品种抗旱性的重要依据。选择抗旱性差异明显的四种类型稻作种质,采用三种干旱胁迫方式,对孕穗期植株叶片的叶肉厚、中脉粗、叶片相对含水量及叶片保水率进行了考察,分析稻作种质在三种处理下各性状相互之间的内在关联及其与品种抗旱性的关系;结果表明叶肉厚、中脉粗、叶片相对含水量及叶片保水率在干旱胁迫下均表现为旱稻类型高于水稻类型。轻度干旱下的叶肉厚与成熟期生物量抗旱指数DRIm2-B极显著相关,与孕穗期生物量抗旱指数DRIm2-H显著性相关。重度干旱下的中脉粗与DRIm2-B极显著相关,重度干旱下的叶片保水率与重度干旱产量抗旱指数DRIm2-Y显著相关,中脉粗和叶片相对含水量在四种种质类型中差异不明显;孕穗期叶肉厚和叶片保水率可分别作为稻作种质抗旱性研究和评价的两个指标。     

25年生‘富士’苹果园冠层光能分布格局及其季节变化规律

为研究不同季节富士苹果园内冠层光能分布及冠层透光率随叶面积指数的变化规律,以25年生‘长富2号’苹果为主要试材,采用3415-LQF5光量子计和WinSCANOPY植物冠层分析仪于生长季节连续测定果园冠层内光能空间分布和叶面积指数的变化。结果表明,不同冠层和不同树冠空间方位的光能分布变化以及最大光照强度的获得与太阳高度角的变化密切相关;不同冠层的消光系数为次外层>内层>外层;不同季节各冠层的光能分布呈现单峰曲线,在正午时刻达到日周期最大值,不同季节冠层平均光照强度依次为春季>夏季>秋季;各冠层生长季节平均光照强度依次为外层>次外层>内层>近地面;相对光照强度小于30%的树冠所占比例随生长季节的延长逐渐增加;年周期冠层透光率与叶面积指数呈相反的变化趋势。相关性分析表明,苹果不同方位冠层平均光照强度与叶面积指数呈显著的负相关（r=-0592*）,与林隙分数呈极显著的正相关（r=0.722**）,与平均叶倾角呈显著的正相关（r=0.647*）。     

Drought Responses of Two Bambara Groundnut (Vigna subterranea L. Verdc.) Landraces Collected from a Dry and a Humid Area of Africa

Drought adaptation strategies of two bambara groundnut landraces, Uniswa Red and S19‐3, collected from contrasting environments in Africa, were compared. Our objectives were to investigate the relative significance of effective stomatal control induced by the abscisic acid (ABA) signalling and osmotic adjustment in regulating plant water relations in general for this legume species. The ABA concentration [ABA] in the leaf increased linearly with declining relative leaf water content, and there were significantly higher [ABA] in Uniswa Red compared with S19‐3 at the final harvest in the drought‐stressed plants. Estimated by a linear‐plateau model, S19‐3 initiated the reduction in transpiration at a significantly lower soil water threshold (FTSW = 0.50 ± 0.024) than Uniswa Red (FTSW = 0.69 ± 0.023) indicating that the latter was more sensitive in reducing plant water use in response to soil drying. A similar trend was found for stomatal closure during soil drying, although the soil water thresholds at which relative stomatal conductance (g_s) started to decline were not significantly different between the two landraces. By an early closure of stomata and hence an early reduction in transpiration rate during soil drying, Uniswa Red could be defined as a ‘water‐saver’ such that it maintains leaf water status to a great extent of soil water deficit. This strategy is important for survival during intermittent drought. While S19‐3 could be defined as a ‘water‐spender’ with a late closure of stomata, hence a late declining of transpiration rate during soil drying allowed the landrace to maximize its water use despite giving up its leaf water relations. Such drought response together with a fast phenological development of S19‐3 indicates that the landrace is capable of escaping from terminal drought while maximizing its water use and productivity when soil water is available.     

基于遥感信息与水稻模型相结合对镇江地区水稻种植面积与产量的估测

为了实现遥感信息与作物模型相结合对镇江地区的水稻种植面积与产量的估测,以便于可以直接利用遥感信息与模型对该地区的水稻生长进行监测,将遥感资料与水稻生产模型(ORYZA2000)相结合,建立遥感数值模拟模型,进行由点及面的区域水稻种植面积及产量的估测。利用遥感数据（8天合成的MODIS和环境小卫星数据）,计算归一化植被指数(NDVI)和增强植被指数(EVI),结合试验区实测的叶面积指数(LAI),建立植被指数与LAI之间的关系,通过模型模拟出的LAI计算出植被指数的浮动值,结合相对应的多时相的遥感数据识别镇江市的水稻,由此可以预报镇江市的水稻种植面积及产量。研究结果表明,模型对水稻生长发育期内的生物量和LAI的模拟较好,水稻LAI与遥感资料计算出的植被指数EVI的幂函数拟合性较好,可以应用这种相关模式识别水稻,并结合ORYZA2000模型提高区域范围的水稻估测精度,同时也体现了遥感信息与作物模型相结合可以很好的监测区域内水稻的生长情况,取得较好的模拟效果。     

氮素基、蘖肥减量对水稻生长及产量的影响

为研究水稻氮肥减量施用的有效途径,以粳稻品种‘通粳981’和‘南粳44’为材料,利用小区试验研究了在穗肥施用量相同条件下氮素基、蘖肥不同施用水平对水稻生长及产量的影响。结果表明：氮素基、蘖肥减量降低水稻高峰分蘖数,对水稻高峰分蘖数出现时期影响不大;氮素基、蘖肥减量使水稻剑叶抽穗后7天叶绿素含量增加,降低水稻干物质的积累,对水稻农艺性状影响不大;氮素基肥减少50%增加了叶基角与叶开角,降低了披垂度;氮素基肥减50%提高水稻成穗率、千粒重,使水稻增产或稳产。     

盐胁迫下粳稻品种南粳9108分蘖特性及其与群体生产力的关系

旨在明确盐胁迫下水稻分蘖发生与成穗规律及其优势叶位,为沿海滩涂水稻高产栽培的分蘖合理利用与调控提供依据。以江苏沿海滩涂大面积种植的常规粳稻南粳9108为试材,设置对照(盐浓度0)、中盐(盐浓度0.15%)和高盐(盐浓度0.3%)环境,比较研究盐逆境下水稻分蘖发生与成穗特性及其对群体产量的贡献。结果表明,对照、中盐和高盐处理的两年平均产量(t hm–2)分别为9.7、7.4和4.2;中盐和高盐处理的穗数、每穗粒数、结实率和千粒重均显著低于对照。与对照相比,中盐和高盐处理下拔节、抽穗和成熟期群体茎蘖数和成穗率均较低。对照的分蘖利用以一次分蘖和二次分蘖为主,一次分蘖发生在第3至第7叶位,第4至第6叶位是分蘖发生与成穗的优势叶位,二次分蘖则以1/4和1/5蘖位优势较强;盐胁迫的分蘖利用以一次分蘖为主,第4至第6叶位是分蘖发生与成穗的优势叶位。盐胁迫下各蘖位的穗长、每穗粒数、着粒密度、一次枝粳数及粒数、二次枝粳数及粒数均低于对照。与对照相比,盐胁迫下水稻单株成穗数少、个体和群体生长协调性差、穗型小,最终单株和群体产量低。     

Crop Management Effects on Pre-and Post-Anthesis Changes in Leaf Area Index and Leaf Area Duration and their Contribution to Grain Yield and Yield Components in Spring Cereals

Seasonal changes in leaf area index (LAI) and leaf area duration (LAD, i.e. LAI integrated over cumulated degree days) have a marked effect on crop productivity. Three case experiments were conducted at Suitia (60°11′N) and Viikki (60°13′N) Experimental Farms, University of Helsinki, Finland, to evaluate the possibilities of accelerating pre-an thesis expansion of leaf area and modifying pre- and post-anthesis LAD in spring cereals through crop management. Effects of time of incorporation of a green manure crop residue into the soil [conventional tillage (autumn ploughing and seed bed preparation in the spring), conservation tillage (sole spring tillage) with and without a green manure crop, common vetch (Vicia saliva I.)]and N fertilizer rate (0, 50, 100kg N ha^?1) on LAI and pre- and post-anthesis LAD in wheat (Triticum aestivum L.) were studied in exp I; green manuring (common vetch) and N fertilizer rate (0,40, 70,110,150kg N ha^?1) in barley (Hordeum vulgare L.), oat (Avena sativa L.), and wheat in exp II; and foliar application of chlormequat chloride (CCC) and ethephon in oat lines (dwarf, naked, modern, landrace) differing in canopy structure in exp III. Time of incorporation of the green manure crop residues into the soil (exp I), green manuring (exp II), N fertilizer rate (exps I and II), and selection for crop growth type (exp III), but not CCC and ethephon, modified LAI and LAD in spring cereals by affecting the rate of pre-anthesis expansion and post-anthesis reduction in leaf area rather than by markedly prolonging the growth period. High rates of N fertilizer accelerated expansion of leaf area, especially prior to stem elongation, and resulted in high pre-anthesis LAD due to enhanced tiller growth (exps I and II) and more tillers per main shoot (exp I). Green manuring increased leaf expansion from the tillering stage most when combined with high N rate, and especially in barley (exp II), but no such effects were found in exp I. Use of a high N fertilizer rate (exps I and II) and green manuring (exp II) also resulted in high post-anthesis LAD. Such modifications enabled higher rates of grain- and head-filling, and in exp I contributed to increased head weight and grain yield. Selection for inherent differences in growth type provided an additional possibility for manipulation of canopy structure and yield formation.     

Comparative Performance of Rice with System of Rice Intensification (SRI) and Conventional Management using Different Plant Spacings

The System of Rice Intensification (SRI) reportedly enhances the yields of rice (Oryza sativa L.) through synergy among several agronomic management practices. This study was conducted to investigate the effects on rice plant characteristics and yield by comparing the plants grown with different methods of cultivation – SRI vs. recommended management practices (RMP) focusing on the impact of different plant spacings. Performance of individual hills was significantly improved with wider spacing compared with closer‐spaced hills in terms of root growth and xylem exudation rates, leaf number and leaf sizes, canopy angle, tiller and panicle number, panicle length and grain number per panicle, grain filling and 1000‐grain weight and straw weight, irrespective of whether SRI or RMP was employed. Both sets of practices gave their highest grain yield with the spacing of 20 × 20 cm; however, SRI yielded 40 % more than the recommended practice. At this spacing, canopies also had the highest leaf area index (LAI) and light interception during flowering stage. The lowest yield was recorded at 30 × 30 cm spacing under both the practices, as a result of less plant population (11 m^?2), despite improved hill performance. During the ripening stage, hills with wider spacing had larger root dry weight, produced greater xylem exudates, and transported these towards shoot at faster rates. These features contributed to the maintenance of higher chlorophyll levels, enhanced fluorescence and photosynthesis rates of leaves and supported more favourable yield attributes and grain yield in individual hills than in closely‐spaced plants. Moreover, these parameters further improved in SRI, apart from the enhanced percentage of effective tillers and showed substantial and positive impacts on grain yield (17 %) compared with recommended practice. In conclusion, wide spacing beyond optimum plant density, however, does not give higher grain yield on an area basis and for achieving this, a combination of improved hills with optimum plant population must be worked out for SRI.     

基于归一化法的双季稻叶面积指数动态预测模型

研究旨在阐明双季稻叶面积指数与辐热积的关系及施氮量对其的影响。选择11个早晚稻品种进行4个施氮水平的小区试验,于关键生育期取样测定叶面积指数(LAI),并对LAI及全生育期的累积辐热积(TEP)进行归一化处理,采用Curve Expert分析软件对相对LAI(RLAI)与相对TEP(RTEP)进行模拟分析,获得6个拟合效果较佳的模拟模型,其中有理方程能够较准确地描述双季稻叶面积指数的动态变化模式,相关系数为0.9677**,具有明确的生物学意义。利用独立的田间试验资料,对构建的模型进行了初步检验。结果表明:早晚稻不同相对TEP所对应的LAI观测值与模拟值之间的根均方差(RMSE)为0.50 m2/m2,表明基于RTEP的RLAI动态模型能够准确地反映双季稻LAI的动态变化。早晚稻群体最大LAI(LAImax)随施氮量的增加呈二次多项式函数增大趋势,相对LAI变化速率随相对辐热积的增加呈\"N\"形变化趋势。研究结果为早晚稻高产栽培和叶面积指数的精确调控提供了理论支撑。     

不同叶龄蘖、穗氮肥组合对粳稻产量及氮素利用的影响

以主茎叶片数不同的粳稻品种吉粳88 (14片)、沈农265 (15片)和沈农1401 (16片)为试材,采用大田筒栽方式,在总施氮量225kghm–2及轻简施肥(基肥、蘖肥、穗肥)模式基础上,设置基蘖肥∶穗肥6∶4和8∶2两种施肥比例,并分设不同源、库叶龄期施氮组合即不同叶龄蘖、穗肥精确施氮组合。分析了不同源库期氮肥运筹模式对水稻农艺性状、产量及氮素利用特性的影响。结果表明:(1)在有效穗数、分化颖花数、产量和氮素利用率方面,吉粳88、沈农265、沈农1401不同氮肥运筹下最佳蘖、穗肥叶龄组合均为6∶4显著高于8∶2。(2)不同氮肥运筹下,吉粳88在8叶(叶龄指数57.1%)、沈农265在9叶(叶龄指数60.0%)、沈农1401在10叶(叶龄指数62.5%)时,即叶龄指数在60%左右时,施用蘖肥效果最佳,最终穗数最多,对保蘖起主要作用;吉粳88在11叶(叶龄指数78.6%)、沈农265在12叶(叶龄指数80.0%)、沈农1401在13叶(叶龄指数81.3%)时,即叶龄指数在80%左右时,施用穗肥效果最佳,最终穗粒数最多,对促花起主要作用。(3)吉粳88-6∶4 (8, 11),沈农26...     

综合农艺管理对夏玉米叶片生长发育及内源激素含量的影响

叶片可直接反映玉米植株的营养状况,是光合作用的主要场所,与干物质积累和产量形成密切相关。本研究以郑单958 （ZD958）为试验材料,以T1代表农民习惯处理; T2代表在T1的基础上,增加种植密度,推迟收获,降低施肥量,并优化施肥时期; T3代表在T2的基础上进一步增加种植密度和施肥量; T4代表在T3的基础上,降低种植密度和施肥量;N代表施氮量处理,设N0、N1、N2和N3分别为0、129.0、184.5和300.0kgNhm^–2,研究综合农艺管理对夏玉米叶片生长及内源激素的调控作用。综合农艺管理措施包括优化耕作方式、种植密度、施肥量、施肥时期和收获时间等。结果表明,施氮量不足导致IAA、ZR和GA₃含量降低, ABA含量升高,叶片SPAD值、叶面积指数（LAI）及比叶重均显著降低;随施氮量的增加,叶片IAA、ZR和GA₃含量增加,ABA含量降低,LAI、SPAD和干物质积累量均显著增加。综合农艺管理处理可调节叶片内源激素含量,其中T4处理IAA、ZR和GA₃含量较T1处理分别高23.1%、9.8%和14.7%;ABA含量降低12.4%;叶片LAI适宜, SPAD值增加4.2%,最终单株干物质积累量增加12.6%。综合农艺管理在降低施氮量,配合最佳的农艺管理方式下,可调节内源激素含量,增加叶片SPAD和比叶重,有利于单株干物质积累,这可能是促进夏玉米产量增加的重要原因之一。