Leaf Area, Grain Yield and Yield Components Following Forage Removal in Triticale

Triticale (X Triticosecale Wittmack) is a cereal that can be simultaneously used for forage and for grain, but this dual purpose is currently limited by a lack of information concerning the effects of forage removal on grain production. Thus, the effect of one or two successive cuttings (simulated grazing) on grain yield, yield components in the main stem and tillers, leaf area and biomass development were studied in four hexaploid triticales grown under irrigation and with high soil fertility. Forage removal reduced grain yield and grain weight per plant in proportion to the number of cuttings, mainly by reducing the number of tillers with spikes at harvest. Whereas foliage reduction did not affect the number of spikelets per spike, kernels per spike, or floral fertility in the main-stem spike, these yield components were drastically reduced in the spikes of tillers. Forage removal affected mean weight per kernel to approximately the same extent in the main stem as in the tillers. The Leaf Area Index (LAI) at anthesis showed significant loss due to cutting, mainly because of a decrease in the number of leaves per plant and in the green area per leaf. This caused similar decreases in the Leaf Area Duration (LAD) from anthesis to maturity. A strong inverse relationship was found between the percent of loss in LAI at anthesis and the final grain yield, suggesting that grain yield was largely dependent upon the ability of the crops to produce new leaf tissue rapidly in the time between cutting and anthesis.     

Effects of an Early Application of Sulphur or Etephon as Foliar Spray on the Growth and Yield of Spring Barley in a Mediterranean Environment

Leaf area development, biomass production and yield of four spring barley varieties grown in a Mediterranean environment (southern Spain) in response to an early application of foliar sulphur or etephon have been studied. Both sulphur and etephon produced similar results compared to the control. Thus, whereas the maximum leaf area index on untreated plots was reached at the beginning of shooting, the growth of foliar area in the treated ones was extended until anthesis and its decline during maturity was similarly retarded. This led to a significant improvement in the biomass at anthesis (which was closely correlated with grain yield) as well as in the leaf area duration during grain filling. These effects were principally due to variations in the number of leaves per plant, caused by a higher tiller production in the treated plants and not by an increase in the number of leaves per tiller or by leaf size.
An application of sulphur or etephon at tillering increases grain yield by raising both the number of ears per plant and per plot, without modifying the number of grains per ear or 1000-grain weight. The similarity between the effects of sulphur and etephon may be due to the fact that sulphur absorbed by the leaves results in an increase in methyonine, the biological precursor or ethylene. The positive correlation between biomass at anthesis and number of ears over grain yield suggests that sink capacity and source activity are closely related and both simultaneously limited by the environment.     

The Influence of Plant Water Stress on Net Photosynthesis and Yield of Sunflower (Helianthus annuus L.)

The effect of plant water stress on net photosynthesis, leaf growth, yield and yield-related components were investigated in a single experiment in order to determine in which way water deficits affect sunflower yields.
Sunflower plants, grown under controlled temperature regimes, were stressed during budding, anthesis and seed filling by withholding water until the leaf water potential reached -1600 and -2000 kPa. Leaf area of unstressed plants significantly exceeded that of plants under severe stress during all growth stages investigated. The CO₂ uptake rate per unit leaf area as well as the total uptake rate per plant, significantly diminished with stress, while this effect drastically increased during the reproductive phase of the plant. Although this resulted in significantly smaller heads and kernels, it did not affect the number of seeds borne in the inflorescence. Severe stress during anthesis and seed filling resulted in more empty kernels. Moderate and severe stress during budding significantly lowered both grain and oil yields while plants that experienced moderate stress during anthesis and seed filling significantly outyielded those under severe stress.     

Leaf Growth and Chlorophyll Content of Oilseed Rape (Brassica napus L.) as Influenced by Nitrogen Supply

An experiment was conducted using a greenhouse hydroponics system to investigate the influence of N nutrition on leaf growth and chlorophyll content in oilseed rape ( Brassica napus L.) during both vegetative and generative growth. Plants were treated continuously with one of three levels of N supply (30, 100 or 170ppm N). Leaf expansion in terms of lamina area of individual leaves and leaf area per plant, and chlorophyll content of leaves during both growth phases were increased significantly by N supply up to 100 ppm N, which was found to be the optimum level for oilseed rape. N supply of 30 ppm N resulted in N stress while 170 ppm N represents an excessive supply. N supply of 100 ppm N enhanced leaf expansion during H–6 weeks after transplanting by 88–260 % over that of 30 ppm N. Lamina areas of younger leaves responded to N nutrition better than did those of older leaves. Leaf area per plant increased 155–194 % due to increasing N supply but leaf number was increased less remarkably (by 25–44 %). N supply enhanced the contents of leaf chlorophyll a , chlorophyll b , and total chlorophyll but had very little influence on chlorophyll a/b ratios; except that increasing N supply tended to reduce these ratios. Results suggest that variation in leaf chlorophyll content of rape plants in response to N nutrition is a function of leaf age and position. The significance of these results in terms of certain physiological implications for the rape plant is discussed.     

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.     

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.     

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GA_3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GA_3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GA_3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。     

Green Area Duration during the Grain Filling Period of an Argentine Wheat Cultivar as Influenced by Sowing Date, Temperature and Sink Strength

The effects of sowing date, air temperature during the grain filling period, sink-strength, and then-interactions on the wheat green area (leaves, leaf sheaths and peduncles) duration from anthesis to total senescence were determined under field conditions at Buenos Aires (Argentina). The individual grain weight was determined as an average of either all grains or basal grains of the spikelets 7 and 8 through the treatments.
The delayed sowing date reduced the period of leaf senescence when it was regarded as calendar time between anthesis to maturity, but it did not affect that period regarded as thermal time. Similarly, the increased temperature has also increased the rate of senescence. On the other hand, the sink strength did not affect the green area duration; since neither the rate nor the period of senescence was altered.
Similarly, both sowing date and mean temperature decreased the individual grain weight, but the sink strength did not affected the weight of the basal grains, which could be interpreted as the effects of the other two factors were independent to the availability of assimilates per grain.
The effect of increased grain filling temperature on reducing grain weight did not operate via reducing the availability of assimilates although it also reduced the total grain area duration. We observed that the increased temperature decreased the individual grain weight of the basal grains at any source sink ratio.     

机械化种植对杂交籼稻F优498产量构成与株型特征的影响

为探明机械化种植杂交籼稻高产群体的株型特征, 以F优498为材料, 采用二因素裂区设计, 研究了不同穴苗数与播期下机直播、机插、手插3种种植方式的株型特征及其与产量构成的关系。结果表明: (1) 不同种植方式株型特征差异显著, 机直播和机插上三叶叶长、叶宽和叶间距大, 但叶基角和披垂度也较大; 手插上三叶大小适宜, 叶片厚而挺直; 机直播和机插株高和着生高度显著大于手插, 但手插比叶重、单株穗数和总叶片数显著高于机械化种植; 机直播的茎蘖夹角、穗粒数和单穗重显著低于机插和手插。推迟播期和低苗处理均使叶片增大, 比叶重、粒叶比、单株穗数、穗粒数和结实率随播期延迟显著降低。单穗重与上三叶长度、宽度、着生高度和株高均呈显著或极显著正相关, 以机插最高, 手插次之, 机直播最低。(2) 机直播产量显著低于机插和手插, 且随播期延迟和穴苗数减少显著降低。产量及其构成与株型特征密切相关, 机械化种植杂交籼稻高产株型的显著特征为适宜的株高、上三叶长度、群体LAI和茎集散度; 叶宽、比叶重、叶间距大和直立性好。足穗和大穗的统一是实现水稻高产的关键, 塑造个体优良的株型与优化群体结构是增产的前提, 机械化种植杂交籼稻应在时间允许的条件下尽早播栽, 穴苗数以3苗左右为宜。     

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.     

Genetic analysis of some chlorophyll fluorescence and productivity parameters in barley (Hordeum vulgare)

Reciprocal crosses were made between five barley genotypes of diverse origin. Parents and 20 F₁S were grown in a greenhouse in a randomized block design with three replications. Each replication consisted of one pot containing three plants. Chlorophyll fluorescence activity of the penultimate leaf (below the flag leaf) of the main stem in each plant was measured at two stages of development (six-leaf stage and anthesis). At anthesis, and after measuring fluorescence parameters, a drought stress was applied. Yield components were measured at complete maturity. Statistical analysis for chlorophyll fluorescence parameters showed high genetic variability for the traits studied at both the six-leaf stage and anthesis, but most fluorescence parameters had decreased by anthesis. General and specific combining abilities of a diallel analysis were significant for most of the characters studied. General combining ability (GCA) values were usually more important than those of specific combining ability (SCA), showing the importance of additive genetic control for the fluorescence traits. Reciprocal effects were not significant for the fluorescence traits studied. A high genetic variability was also observed for yield components. Additive gene effects for plant weight, spike number, spike weight, number of grains per plant and 1000-grain weight were demonstrated. Potential photosynthetic activity (Rfd) at anthesis was positively correlated with plant weight, spike number per plant and 1000-grain weight.     

基于叶形纸称重法的烤烟田间最大叶面积指数研究

为给科技人员正确应用烤烟叶面积相关指标提供参考依据,在现行优质烟生产条件下,针对14个基因型烤烟叶面积指数最大时期的关联指标进行研究。结果表明：采用叶形纸称重法测算烤烟叶面积校正系数是完全可行的。田间单株叶面积在1.84~2.90 m²,平均为2.08 m²;最大叶面积指数在3.07~4.83,平均为3.47。不同基因型烤烟之间,叶面积校正系数和最大叶面积指数差异较大,不宜采用某一常数值进行机械套用,而应针对特定品种进行探索。     

Effects of Soil Drought in the Generative Phase of Development of Field Bean (Vicia faba L. var. minor) on Leaf Water Status, Photosynthesis Rate and Biomass Growth

The effects of 10-day periods of soil drought during flowering (DI) or pod growth (DII) and during both these phases (DI + DII) on leaf water status, photosynthesis rate, plant growth and production of biomass was studied in pot experiments with field bean. Soil water content during drought spells were kept at 30% of field water capacity. Soil water deficiency DI and DII depressed the leaf water potential relatively to control by about 100 % and 140 % respectively, increased the water deficit by 100 % and 120 % and reduced photosynthesis rate by 80 % and 90 %. Rehydration of tissues completely abolished any decline of photosynthesis rate caused by drought DI, but after drought DII photosynthesis rate remained depressed by about 30 % even after rehydration. Drought periods DI and DII caused more rapid withering of leaves, a decline in the total leaf area and a temporary increase of root weight.
Drought occuring at flowering (DI) also activated the mechanism of plant adaptation to water deficiency during the pod formation phase (DII). Single or double periods of drought had not any significant influence on the number of pods and seeds, but decreased their weight.     

对生玉米叶面积分布、 蒸腾速率和水分利用率的研究

研究了6个品种(系)的对生和互生玉米的叶面积分布、 蒸腾速率(Tr)和水分利用率(WUE)。 结果表明, 对生玉米单株叶数和叶面积比互生玉米分别高出192%～220%和130%～190%。 两者的不同叶位与叶面积之间均呈极显著的二次抛物线回归关系, 即判断得最大叶面积的叶位数为6。 后期(灌浆期起), 对生玉米叶绿素含量高于互生的, 差     

Allometric Model for Leaf Area Estimation in Black Pepper (Piper nigrum L.)

Black pepper (Piper nigrum L.) is an important spice used in cooking and medicine. It is cultivated in more than 20 countries in Asia, Africa and Latin America. India is a major producer, consumer and exporter of black pepper. Leaf area (LA) is an indicator of crop growth and productivity. This study was undertaken to develop a method of estimating the individual LA of black pepper directly without the necessity for time‐consuming area measurements. Ten black pepper lines were used in the study. Ninety matured leaves were collected from each line and an allometric relationship was derived by logarithmic transformation between actual leaf area (ALA) measured using the electronic leaf area meter LI‐3000 A (LI‐COR, Inc., Lincoln, NB) and leaf length (LL). The correlation coefficient (r) between ALA and LL ranged between 0.8692 and 0.9644 and the standard error (S.E.) between 0.0822 and 0.1149. The allometric models for 10 lines were: Panniyur 1, LA=0.7114 (LL)^1.8409; Panniyur 2, LA=0.3692 (LL)^2.067; Panniyur 3, LA= 0.6148 (LL)^1.8838; Panniyur 4, LA=0.8355 (LL)^1.7694; Sreekara, LA=0.8984 (LL)^1.6692; Subhakara, LA=0.8384 (LL)^1.738; Panchami, LA=0.3691 (LL)^2.0749; Pournami, LA=0.4487 (LL)^1.9718; Kottanadan, LA=0.3474 (LL)^2.0634; P‐24, LA=0.7579 (LL)^1.654. These allometric models were used to calculate LA, which was then compared with the actual LA, and the correlation coefficient (r) between them was found to be > 0.99. These allometric models can be used to estimate the LA of individual leaves of black pepper. The approximate total LA of a vine can be obtained using following formula: total leaf area of black pepper vine (cm²) = number of laterals per vine × number of leaves per lateral × leaf area of individual leaf.     

Identification of growth stage dependent expression of partial resistance of barley to powdery mildew

Summary Genotypic differences for growth stage dependent expression of partial resistance to barley powdery mildew have been identified on the basis of two components of resistance in the glasshouse and the pattern of epidemic development in the field.Differences for infection frequency and proportion of sporulating colonies were highly significant between the 16 genotypes investigated at four stages of plant development in the glasshouse. Both resistance components were significantly correlated mutually (r=0.73 to 0.86) and with the infection level on leaves developed at comparable growth stages in the field (r=0.52 to 0.73). The infection level of seedlings in the glasshouse was significantly correlated with the infection level of the leaves of the first until the third node in the field (r=0.70 to 0.73). Adult plant resistance was predominantly expressed at the uppermost leaf. A clear genotype × growth stage interaction was apparent for infection level; some genotypes showed partial resistance predominantly at the seedling stage and others predominantly at the adult plant stage.Abbreviations IF Infection Frequency, number of colonies per cm² leaf area, glasshouse experiment - IL Infection Level, number of colonies per cm² leaf area, field experiment - PSC Proportion Sporulating Colonies from total number of colonies, glasshouse experiment     

The response to temperature of leaf area in tomato genotypes. II. The rate of leaf production

Summary Genotypic variation in the response to temperature of the rate of leaf production is reported. Leaf production was measured as the rate of successive leaves passing a specific length and by dissecting plants to obtain the rate of leaf initiation. These results together with the results of leaf size from the previous paper. are compared to the effect of temperature on the total leaf area. The use of information from these experiments in selecting for increased leaf area at low temperature is discussed.Guestworker Project Group Tomato Physiology.     

不同留叶数对美引烤烟新品种NC297生长及产质量的影响

通过大田试验,研究了不同留叶数（每株留叶16、20、24片）对美引NC297烤烟新品种生长及产质量的影响,结果表明：随着留叶数的增加,烟株株型与上部叶面积有明显的差异;留叶数的多少对中、下部叶片大小和单叶重的影响较小,对上部叶的影响较大;留叶数偏少,烟叶的产量会受到一定的影响,而留叶数过多,均价、上等烟比例将受到不利影响。综合产、质量效益,NC297以留叶数20片为最佳。     

不同留叶数对美引烤烟新品种NC297生长及质量的影响

通过大田试验,研究了不同留叶数(每株留叶16、20、24片)对美引NC297烤烟新品种生长及产质量的影响,结果表明:不同留叶数的烟株株型和株高明显不同,而茎围与节距的差异不显著;不同留叶数对中、下部叶片大小和单叶重的影响较小,对上部叶的影响较大;留叶数偏少(L16),均价虽较高,但对烟叶的产量和产值会有不利影响,而留叶数偏多(L24),产量虽有所增加,但均价、上等烟比例将受到不利影响;留叶数为20片的两糖差值小(1.01),总氮、烟碱适中,钾/氯高(8.44);留叶数偏多或偏少,两糖差值均偏大,总氮、烟碱偏高,钾/氯低。综合产、质量效益及各项化学成分指标,NC297以留叶数20(L20)片为最佳。     

Effect of Water Stress on Physiological Attributes and their Relationship with Growth and Yield of Wheat Cultivars at Different Stages

The effects of water stress on physiological attributes of drought‐sensitive (Kalyansona) and drought‐tolerant (C‐306) wheat cultivars were studied in a pot experiment. Water stress was imposed by withholding irrigation at boot and anthesis stages. Leaf water potential, leaf osmotic potential and leaf turgor potential (measured with pressure chamber and osmometer), as well as leaf diffusive resistance, leaf transpiration rate and leaf‐to‐air transpiration gradient (measured with a steady‐state porometer) were measured diurnally. Growth and yield parameters were recorded after harvesting of the crop. Triplicate data were analysed using a completely randomized design and correlations amongst these parameters were computed. Water stress was found to reduce diurnal leaf water potential and leaf osmotic potential in both the genotypes but leaf osmotic potential was significantly higher in the drought‐tolerant cultivar C‐306 than in the drought‐sensitive cultivar Kalyansona. Positive turgor was recorded in both the genotypes under water stress and non‐stress conditions. Water‐stressed plants showed significantly lower turgor potential than control plants. In diurnal observations, water‐stressed plants exhibited significantly higher leaf diffusive resistance in both genotypes at both stages. The diffusive resistance of C‐306 was predominantly higher than that of Kalyansona. Water stress decreased leaf transpiration rate at both stages but the reduction was higher at the anthesis stage. The leaf‐to‐air temperature gradient was much higher in C‐306 than in Kalyansona at the boot stage but at the anthesis stage genotypic variation was non‐significant. The capacity to maintain cooler foliage was lower at the anthesis stage than at the boot stage in both the cultivars. Shoot dry weight, number of grains, test weight, grain yield, biological yield and harvest index decreased to a greater extent when water stress was imposed at the anthesis stage, while imposition of water stress at the boot stage caused a greater reduction in plant height and number of tillers. Similarly, water stress caused a smaller reduction in growth, yield and yield attributes in C‐306 than in Kalyansona. In general, the correlation coefficient of grain and biological yield with water potential and its components was positive and highly significant. Similarly, turgor potential was also correlated positively and significantly with grain yield at both the stages, but with biological yield it was significant only at the anthesis stage. A negative and significant correlation was obtained for diffusive resistance and leaf‐to‐air temperature gradient with grain yield at the boot and anthesis stages. The rate of transpiration was also positively and significantly correlated to grain and biological yields at both the stages. Amongst the yield attributes, number of leaves and number of tillers were positively correlated at the anthesis stage, whereas leaf area and shoot dry weight were significantly correlated with grain and biological yields at both the stages.