油菜叶面积和叶鲜重估计研究

为快速获取大田油菜长势监测信息,针对不同栽种方式和施肥水平对油菜叶片生长的影响,建立单株油菜叶面积和叶鲜重估计模型。分别于2013—2015年的2个油菜种植季,设置不同施肥水平下直播和移栽油菜试验小区。在油菜叶片形态差异最大的六叶期和蕾薹期,测量样株所有叶片的长、宽、面积和鲜重,采用方差分析对比栽种方式和施肥水平对油菜叶片生长的影响,运用麦夸特法+通用全局优化法建立叶面积和叶鲜重的长宽估计模型。在不同施肥水平和栽种方式下,2个生长期的油菜叶面积和叶鲜重与叶宽关系均比叶长更明显;相同条件下蕾薹期油菜叶片变异程度比六叶期要大,2个时期不同施氮水平、栽种方式下油菜叶面积、叶鲜重差异均达到极显著水平,但两者对叶片的交互作用未达到显著水平。叶宽线性模型估算叶面积和叶鲜重的预测R²为0.89、0.84,RMSEP为32.40 cm²、2.54 g,长宽幂函数模型与常规的长宽线性模型相比,叶面积和叶鲜重的预测R²为0.97、0.94,RMSEP为 12.92 cm²、0.86 g。不同生长条件下,叶宽线性模型可用于快速获取油菜单片叶面积和叶鲜重,长宽幂函数模型受施肥水平、栽种方式、叶形、生长期等因素影响较小,适用于精确估计单株油菜叶面积和叶鲜重。     

图像处理技术在唐菖蒲叶面积测定中的应用

以数码相机结合Photoshop软件实测的唐菖蒲（Gladiolus hybridus Hort）叶面积为参照，用不同叶位叶片的长径（L）和宽径（W）求得唐菖蒲叶面积的矫正系数和回归方程。以矫正系数（K）法求算叶面积：品种“桃红”LA=0.65LW，品种“玫瑰粉”LA=0.71LW；回归方程法求算叶面积：“桃红”LA=0.58×L×W+ 7.02，“玫瑰粉”LA=0.69×L×W+ 1.58。经方差分析比较证明，应用回归方程法计算的叶面积比用矫正系数法更为可靠。     

Genetic Analysis of Morpho-Physiological Traits in Chickpea

The present study was conducted to investigate the genetic inheritance of morpho-physiological leaf traits in chickpea (Cicer arietinum L.). The experimental material comprised six generations, viz., two inbred parents, ‘T88’ and ‘Bold Seeded’, having contrasting leaf traits, and their derived F₁, F₂ and backcross of F₁ to either parent (B₁ and B₂). The experiment was randomized complete block design with three replications. Genetic parameters were estimated by generation mean analysis using all the six generations. Data were collected on individual plants within each family just before flowering on leaflet area (LA), number of leaflets per leaf (LL), rachis length (RL), and leaflet density (LD), which was calculated as number of leaflets per unit length of rachis. A simple additive-dominance model was found to be adequate to describe the inheritance of LL and LA, while dominance × dominance (i.e. [1]) and additive × dominance (i.e. [i]) interactions were also significant for RL and LD, respectively. Improvement or seed yield per plant may result from selection for LA by improving both RL and LL. Leaflet area may be included in the ongoing selection schemes, as a supplementary trait to increase the speed of improvement in seed yield per plant. Lanceolate leaflet shape was observed to be monogenically dominant over obovate leaflet shape, and segregated independently from purple/white flower color.     

Dry matter partitioning and canopy traits in wheat and barley under varying N supply

The prediction of the allocation of carbon and nitrogen into the different organs, e.g., leaves, stems, roots of a growing plant is a pivotal part of mechanistic growth models. Based on 2 year (winter wheat) and 3 year (winter barley) field trials with different N treatments (0–240 kg N ha⁻¹), the objectives of this study were to verify currently used parameters for (i) specific leaf area, and (ii) allometric relationships between leaf and stem dry matter (DM).Green area index (GAI) differed between years and increased with N supply rate. The course of the specific leaf area (SLA) within the growth period after winter showed a large variation between the years as well as between the N treatments. During stem elongation, SLA positively correlated with GAI in both crops, indicating that leaves became thinner when the canopy was denser. The allometric relationships between stem and leaf dry DM clearly varied with the growth stages. Stem DM of wheat showed a higher proportion of the total above-ground biomass compared to barley. The effect of N fertilization on allometry remained small during early growth stages in barley, whereas in wheat, an increased N supply significantly decreased the proportion of stem DM.Our results suggest similar GAI and SLA patterns for wheat and barley, albeit depending on the N supply. Especially, using a constant SLA in plant growth models seems to be not suitable.     

Effects of Soil Salinity and Plant Density on Yield and Leaf Senescence of Field‐Grown Cotton

The response of cotton to constant salinity has been well documented under controlled conditions, but its response to changing salinity under field conditions is poorly understood. Using a split‐plot design, we conducted a 2‐year field experiment to determine the effects of soil salinity and plant density on plant biomass, boll load, harvest index and leaf senescence in relation to cotton yield in three fields with similar fertility but varying salinity. The main plots were assigned to weak (electrical conductivity of soil saturated paste extract, ECe = 5.5 dS m^?1), moderate (ECe = 10.1 dS m^?1) and strong (ECe = 15.0 dS m^?1) soil salinity levels, while plant density (3.0, 4.5 and 7.5 plants m^?2) was assigned to the subplots. Soil salinity had a negative effect on seedcotton yield, but the negative effect was compensated for by increased plant density under strong‐salinity conditions. Seedcotton yield under weak salinity changed little with varying plant density, but the medium plant density yielded better than the low or high plant density under moderate salinity. Plants accumulated 49 and 112 % more Na⁺ in leaves under moderate and strong salinity than under weak salinity. Strong salinity also led to higher boll load and early leaf senescence. Plant density had no effect on Na⁺ accumulation in leaves, but greatly reduced boll load and delayed leaf senescence. Plant biomass, maximum leaf area index and harvest index were greatly affected by salinity, plant density and their interaction. Accelerated leaf senescence under strong salinity was attributed to the high boll load and increased accumulation of toxic ions like Na⁺ in leaves, while delayed leaf senescence with increased plant density was attributed to the reduced boll load. Optimal yield can only be obtained with proper coordination of total biomass and harvest index by modification of plant density based on salinity levels.     

乙矮合剂对不同密度夏玉米花粒期不同部位叶片衰老特性的影响

为探讨乙矮合剂对密植夏玉米叶片衰老及后期早衰的调控机制, 建立华北夏玉米区密植高产稳产化学调控技术, 以中单909和浚单20为材料, 设置乙矮合剂(ECK)和密度梯度处理, 研究密度梯度对夏玉米花粒期不同部位叶片衰老特性的影响与ECK的调控效应。结果表明, 随密度增加, 两品种花粒期单株叶面积减小且降幅增大; 各叶位叶片的叶绿素相对含量和可溶性蛋白含量呈下降趋势; 超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性呈降低趋势; 丙二醛(MDA)含量则呈增高趋势; 上述指标在叶位和品种间存在差异。ECK处理显著提高各密度不同部位叶片SOD、CAT、POD活性和叶绿素相对含量及可溶性蛋白含量, 显著降低MDA含量; 单株绿叶面积降幅减小, 叶片衰老进程延缓, 衰老程度减轻。ECK处理后, 较高密度群体下(7.5~10.5万株 hm^-2), 中单909和浚单20较各自对照分别增产5.59%~6.63%和6.73%~8.10%。因此, 采用合理的种植密度结合喷施乙矮合剂可作为华北夏玉米区高产栽培的重要技术措施。     

A Simple Drought‐Sensitive Model for Leaf : Stem Partitioning of Wheat

We investigated the leaf : stem partitioning of winter wheat (Triticum aestivum L. varieties ‘Dekan’ and ‘Batis’) with and without drought influence. Irrigated and drought‐stressed winter wheat, grown in a rainout shelter in 2009/10 and 2013/14, were sampled during shoot elongation phase at the experimental Farm Hohenschulen located in Northern Germany. The data set contains leaf (DM_L) and stem dry masses (DM_S), as well as measured water contents for several soil layers. A reduced relative dry matter allocation to leaves was observed under drought stress. Our results clearly show that, if simulated leaf : stem partitioning is not sensitive to drought, this will cause a positive bias in simulated leaf and a negative bias in simulated stem dry matter under water‐limited conditions. This is in accordance with previous studies which revealed that crop simulators often overestimate the impact of drought on light‐use efficiency, whereas the consequences on leaf area development are underestimated. However, the drought stress‐induced shift in leaf : stem partitioning is yet not considered by most common wheat crop simulators. Our aim was to fill the gap in simulation of drought stress implications on leaf area development. A simple allometric model for leaf : stem partitioning () was parameterized. Starting from the allometric leaf : stem relationship observed under optimum water supply, a correction term was introduced, which allows to adapt the partitioning to drought stress conditions. The lg‐transformed root‐weighted soil water potential in the rooting zone (lgψ_root, lg(hPa)), calculated as a function of measured water contents and simulated root distribution, was used as a drought stress indicator. The linear correction term assumes an increase of the stem fraction, proportional to the difference between lgψ_root and a drought stress threshold (pF_crit, lg(hPa)). The analysis revealed that the shift in allometric partitioning towards stem fraction starts with lgψ_root greater than 1.92 [lg(hPa)]. The slope of the relative increase of dry matter allocated to the stem fraction was determined with 0.26 [lg(hPa)^?1]. Both parameters of the correction term were found to be highly significant. Implications for crop modelling are discussed.     

Allometric Relationships of Growth Components in Maize (Zen mays L.) Cultivars

Allometric relationship (W₁=αW₂^β, where α and β are the parameters) was fitted among growth components in two maize cultivars viz., Decani hybrid and Deccan 101 in order to obtain estimates of other components of the plant system which are time consuming measurements. The results of the agronomic field trial conducted at the University of Agricultural Sciences, Bangalore were used. This model's predictability was compared with linear regression model. In both the cultivars, allometric model using leaf area (LA - W₂.) and leaf dry matter (LDM - W₂) simulated total dry matter production (DMP - W₂) by 79 to 98 % of actual values. Further allometric model fitted well to predict stem dry matter by 91 to 93 % using LDM and LA 89 to 92 % using LDW. Whereas linear regression model estimated total DMP by 95 to 96 % using cob dry matter. In case of LDM - LA association, linear regression model was found to be the best than other model. The leaf area decreased after silking in both the cultivars and the ratio of growth rates of DMP – LA ( β ₂) was negative. Between cultivars, cv. Deccan 101 had higher R² values in most of the relationships than cv. Deccan hybrid indicating the varietal difference.     

Salt Tolerance is Associated with Differences in Ion Accumulation,Biomass Allocation and Photosynthesis in Cowpea Cultivars

Cowpea is widely cultivated in arid and semi‐arid regions of the world where salinity is a major environmental stress that limits crop productivity. The effects of moderate salinity on growth and photosynthesis were examined during the vegetative phase of two cowpea cultivars previously classified as salt‐tolerant (Pitiúba) and salt‐sensitive (TVu). Two salt treatments (0 and 75 mm NaCl) were applied to 10‐day‐old plants grown in nutrient solution for 24 days. Salt stress caused decreases (59 % in Pitiúba and 72 % in TVu) in biomass accumulation at the end of the experiment. Photosynthetic rates per unit leaf mass, but not per unit leaf area, were remarkably impaired, particularly in TVu. This response was unlikely to have resulted from stomatal or photochemical constraints. Differences in salt tolerance between cultivars were unrelated to (i) variant patterns of Cl^? and K⁺ tissue concentration, (ii) contrasting leaf water relations, or (iii) changes in relative growth rate and net assimilation rate. The relative advantage of Pitiúba over TVu under salt stress was primarily associated with (i) restricted Na⁺ accumulation in leaves paralleling an absolute increase in Na⁺ concentration in roots at early stages of salt treatment and (ii) improved leaf area (resulting from a larger leaf area ratio coupled with a larger leaf mass fraction and larger specific leaf area) and photosynthetic rates per unit leaf mass. Overall, these responses would allow greater whole‐plant carbon gain, thus contributing to a better agronomic performance of salt‐tolerant cowpea cultivars in salinity‐prone regions.     

我国玉米自交系叶片保绿性及其与产量的关系

选用我国75个常用不同基因型玉米自交系,对其叶片保绿性参数进行了定点动态测定。结果表明,不同自交系抽丝后叶片保绿度的变化均符合方程y = ae^b-cx/ (1+e^b-cx),成熟期的绿叶数、成熟期叶绿素含量和相对绿叶面积平均衰减速率(V_m)可作为区分玉米保绿型与非保绿型的关键指标。按照Hiechical聚类分析方法,筛选出12个保绿型自交系,其成熟期相对绿叶面积在60%以上,其V_m平均值为0.687% d^-1,在生长季内相对绿叶面积无大幅度衰减,成熟期绿叶数多,叶绿素含量较高;其余63个为非保绿型自交系,还可分为植株叶片衰老较快型与植株叶片衰老较慢型两个亚类。不同自交系抽丝后叶片保绿性与叶面积持续期、单株产量均呈正相关。保绿型的叶面积持续期和单株产量比非保绿型分别高20.02%~23.87%和50.44%~59.38%;与非保绿型自交系相比,保绿型在籽粒灌浆期绿叶面积大,叶绿素含量高,群体光合速率高,光合作用时间长,因而生物产量较高。     

毛白杨无性系叶面积的回归测算

利用快速、精准的方法,建立了4个不同毛白杨无性系的叶面积与其叶长、叶宽、以及叶长×叶宽之间的线性回归和幂函数回归方程。结果表明：1）毛白杨不同的无性系叶形指数差异较大,不同无性系的回归方程也不一样,应针对无性系计算叶面积;2）叶片生长的不同阶段叶面积的回归方程不同,因此应针对叶片的不同生长阶段确定回归方程。3）一元线性回归方程中,叶面积和叶长、叶宽的乘积的相关性最好,但只适用于功能叶片的测量;而幂函数回归方程无叶片大小限制,叶面积和叶宽的相关性较好并且测量方便,毛白杨无性系50号叶面积和叶宽幂函数回归方程为LA=1.0014×W1.8295,83号回归方程为LA=0.863×W1.832,30号回归方程为LA=0.554×W2.051,B331号回归方程为LA=1.639×W1.600。因此在今后的生产实践中,可通过测定4个毛白杨无性系的叶宽,利用其幂函数回归方程,估算叶面积。     

Genetic diversity in vegetative traits of utazi (<Emphasis Type="Italic">Gongronema latifolia</Emphasis> Benth) grown for two cropping seasons in Nsukka

Utazi (Gongronema latifolia Benth.) clones obtained from some localities of Southeastern Nigeria were used to establish a research field in a randomized complete block design with three replications. The extent of genetic diversity and selections on the vegetative traits were determined. Results obtained showed diverse genetic base of the clones in the vegetative traits. Higher genetic variability was observed in leaf area/plant, length of the longest vine/plant and number of leaves/plant in the clones. However, significant environmental effect on length of the longest vine/plant and number of vines/plant resulted in lower broad sense heritability estimate value for the traits. The broad sense heritability estimate for size of the cordate base, leaf area, breadth, and length are high ranging from 74–86 %. The year had no significant effect on the traits with high broad sense heritability. Strong positive correlation was observed between length of breadth and leaf area (r = 0.97; n = 46). The principal component analysis indicated that the vegetative traits of the species could be classified based on the leaf area determined by leaf length, breadth and size of the cordate base as well as the quantity of leaves on a clone. The GGE biplot analysis revealed the pattern clones were distinctly positioned; clone EBS-15-NKALAGU had the highest level of all the attributes measured, while EBS-16-ABAKALIKI had the least. Hence, clones EBS-15-NKALAGU, ENS-08-MBU and ENS-12-0KUTU could be selected for improvement and production purposes because they rated high in the vegetative traits with high genetic effects in their expression over the two years.     

Genetic gains for physiological traits associated with yield in soft red winter wheat in the Eastern United States from 1919 to 2009

Wheat (Triticum aestivum L.) breeding strategies can benefit from periodic evaluation of genetic gains for physiological and morphological traits, and their contribution to yield progress over time in a particular environment. The objective of this research was to expand the recent work at Virginia Tech on genetic yield improvement in soft red winter (SRW) wheat and determine the magnitude of progress for several physiological traits in 50 SRW wheat cultivars released from 1919 to 2009. Physiological traits evaluated here were extensively reported in the literature to be relevant for future wheat breeding as they directly contributed to yield increase under optimum and suboptimal environmental conditions; these traits include canopy temperature depression (CTD), flag leaf width (W), flag leaf area (LA), flag leaf dry weight (DW), flag leaf specific area (SLA), SPAD (soil plant analysis development) chlorophyll reading, and grain ¹³C isotope discrimination (Δ). Replicated experiments were performed at Warsaw and Holland, VA, in 2009–2010 and 2010–2011 growing seasons. Results showed that three traits consistently changed in magnitude over time and, at the same time, were significantly (p < 0.01) related to yield; they were LA, smaller leaf area-higher yields; DW, lighter leaves-higher yields; and Δ, higher Δ-higher yields. CTD decreased in magnitude and SLA, W, and SPAD chlorophyll reading did not significantly change over time. Our data suggest that further yield increase in the SRW wheat grown in eastern Unites States can be achieved through selection of cultivars with smaller leaves, and with high Δ.     

Changes in the morphological traits of maize genotypes in China between the 1950s and 2000s

Maize (Zea mays L.) morphological traits influence light attenuation within the canopy, and, ultimately, yield. The objectives of this 3-year field study were to: (i) examine the morphological characteristics of specific genotypes using varieties of maize that were widely used in Chinese agriculture from the 1950s to the 2000s; (ii) assess the canopies and yields of maize populations in relation to changes in their morphological characteristics. There were significant decrease on the ear ratio, center of gravity height and leaf angle with improved genotypes regardless of plant density. However, the ear leaves and adjacent leaves appeared to be longer in improved maize varieties. The mean leaf orientation value (LOV) and individual LOVs increased considerably during the time series of the genotypes, but more obvious changes in LOV occurred in the uppermost leaves. The average leaf area (LA) per plant and LA on the ears increased significantly from the 1950s to the 2000s. At the optimum density, current hybrid's canopy architecture was more compact, having short plant height and more upright leaf. The SDLA above or under ear significantly increased with improving genotypes, mainly due to new hybrids allowing the use of more individuals per area and thus increasing leaf area index (LAI). At the highest plant density, new hybrids had the rates of light transmittance (0.04–0.05), low attenuation coefficient (K = 0.47) and gained the highest yield. Leaf angle and LOV were highly correlated with TPAR/IPAR on ear, K, grain yield. Consequently, yield improvement in maize was probably a result of increased plant density tolerance through dependence on changes in leaf orientation characteristics.     

5‐Aminolevulinic Acid Activates Antioxidative Defence System and Seedling Growth in Brassica napus L. under Water‐Deficit Stress

The present study assesses the effects of 5‐aminolevulinic acid (ALA, 0, 0.1, 1 and 10 mg l^?1) on the growth of oilseed rape (Brassica napus L. cv. ZS758) seedlings under water‐deficit stress induced by polyethylene glycol (PEG 6000, 0 and ?0.3 MPa). Water‐deficit stress imposed negative effects on seedling growth by reducing shoot biomass, cotyledon water potential, chlorophyll content and non‐enzymatic antioxidants (glutathione and ascorbic acid) levels. On the other hand, water‐deficit stress enhanced the malondialdehyde (MDA) content, reactive oxygen species (ROS) production, enzymatic antioxidants activities, reduced/oxidized glutathione ratio (GSH/GSSG) and reduced/oxidized ascorbic acid (ASA/DHA) ratio in seedlings. Application of ALA at lower dosages (0.1 and 1 mg l^?1) improved shoot weight and chlorophyll contents, and decreased MDA in rape seedlings, whereas moderately higher dosage of ALA (10 mg l^?1) hampered the growth. The study also indicated that 1 mg l^?1 ALA improved chlorophyll content, but reduced MDA content and ROS production significantly under water‐deficit stress. Lower dosages of ALA (0.1 and 1 mg l^?1) also enhanced GSH/GSSG and ASA/DHA as compared to the seedlings under water‐deficit stress. The antioxidant enzymes (ascorbate peroxidase, peroxidase, catalase, glutathione reductase and superoxide dismutase) enhanced their activities remarkably with 1 mg l^?1 ALA treatment under water‐deficit stress. It was also revealed that 1 mg l^?1 ALA treatment alone induced the expression of APX, CAT and GR substantially and under water‐deficit stress conditions ALA treatment could induce the expression of POD, CAT and GR to a certain degree. These results indicated that 0.1–1 mg l^?1 ALA could enhance the water‐deficit stress tolerance of oilseed seedlings through improving the biomass accumulation, maintaining a relative high ratio of GSH/GSSG and ASA/DHA, enhancing the activities of the specific antioxidant enzymes and inducing the expression of the specific antioxidant enzyme genes.     

A Comparison of Screening Criteria for Salt Tolerance in Wheat under Field and Controlled Environmental Conditions

Although many screening criteria have been suggested to distinguish between genotypes for their salt tolerance under controlled environmental conditions, there is a need to test these criteria in the field. Saline soils are often complex and, therefore, unlikely to show a simple relationship to controlled conditions. To address this deficit, different agronomic and physiological screening criteria for salt tolerance in wheat at different stages were examined under both field and controlled conditions. Four wheat genotypes differing in their salt‐tolerance levels were grown in salt‐affected soil at two different locations and also under greenhouse conditions. Dry weight and leaf area of the upper and lower two leaves of the main stem and total dry weight at Zadoks scale 47 were measured in plants grown under field conditions. The concentrations of Cl^?, Na⁺, K⁺ and Ca²⁺ in the upper and lower two leaves of the main stem at Zadoks scale 47 and different yield components were measured in plants grown under both conditions. Our results indicate that measurements derived from the upper two leaves of the main stem were generally more effective as screening criteria than those from the lower two leaves. Correlation coefficients between grain yield and either dry weight or leaf area of the upper two leaves of the main stem indicated that dry weight is inferior to leaf area as a screening criterion under field conditions. Number of sterile spikelets per plant performed well under both conditions, whereas the number of spikelets per plant and 1000‐grain weight failed to distinguish the differences of salt‐tolerance levels among genotypes accurately. Weight and number of grains per plant and number of fertile spikes per plant were poor criteria under controlled conditions, but effective under field conditions. The maintenance of low Cl^? and Na⁺ concentrations in the upper two leaves offered the best guide to salt tolerance under both conditions. Potassium concentration was a poor criterion compared with the selectivity of K⁺ over Na⁺, which was useful under both field and controlled conditions. Calcium concentration and Ca²⁺ over Na⁺ selectivity in the upper and/or lower two leaves of the main stem were also effective in ranking genotypes according to their salt tolerance under both field and controlled conditions. Therefore, we conclude that simple measurements of the upper two leaves of the main stem including a straightforward measurement of leaf area, visually estimating the number of sterile spikelets, and a quick, practical determination of Na⁺ and Ca²⁺ concentration constitute effective criteria to screen wheat genotypes for salt tolerance under both field and controlled conditions.     

基于AutoCAD软件确定番茄与青椒叶面积的简易方法

为准确而方便的获取番茄和青椒的叶面积,本研究利用扫描仪获取叶片图像,通过AutoCAD获取叶片的实际面积,并与田间实测叶长、叶宽及叶片长宽乘积分别进行回归分析,分别建立了叶长、叶宽及长宽乘积与实际叶面积的回归模型。研究结果表明,叶长、叶宽与叶面积呈幂函数关系,长宽乘积与叶面积呈线性关系;分别对3种估算模型模拟值进行误差分析结果显示,叶长、叶宽回归模型的模拟精度较差,而长宽乘积回归模型的模拟误差很小,精度较高,可以较真实地反映番茄和青椒叶面积的实际大小,叶片长宽乘积估算叶面积的折减系数分别为0.6393和0.6509。     

超高产夏玉米花粒期不同部位叶片衰老与抗氧化酶特性

为探讨超高产玉米叶源衰老特征, 揭示其抗氧化关键酶及膜脂过氧化特性, 为玉米衰老调控和高产栽培提供依据, 本研究在大田条件下, 以我国创高产纪录的夏玉米为例, 从单株水平上对高产纪录试验(EHYR)和普通生产田(MCFF)玉米叶片衰老及抗氧化酶特性比较表明, EHYR产量达19 349 kg hm^-2, 是MCFF的2.28倍。MCFF和EHYR叶片分别在开花后30 d和50 d进入速衰期, MCFF叶片衰老比EHYR提前20 d;速衰期EHYR叶面积降幅比MCFF低5.7%。EHYR在籽粒灌浆后期, 中上部叶片净光合速率较高, 可溶性蛋白含量明显高于MCFF, 而MDA含量则维持较低水平。在叶片衰老过程中, 自开花后20 d开始, EHYR上部和中部叶片SOD活性较高, 下部叶片则以SOD、POD和CAT三者活性较高;MCFF仅中部叶片POD和CAT活性较高。EHYR叶片衰老程度与CAT活性极显著负相关, MCFF叶片衰老与SOD和POD活性显著负相关, 且二者叶片衰老进程中SOD、POD、CAT的直接作用大于间接作用。与MCFF相比, EHYR叶片除具较高SOD和POD活性外, 在籽粒灌浆后期同时保持较高CAT活性和可溶性蛋白含量是降低膜脂过氧化程度, 延缓叶片衰老的重要原因。开花后20 d是EHYR与MCFF叶片衰老出现差异的生理临界点, 因而在此时期之前调控更有利于延缓衰老。     

Identification of novel QTL for leaf traits in soybean

Several leaf traits of soybean (Glycine max L. Merr.), including leaf area (LA), leaf shape (LS) and specific leaf weight (SLW) may be related to soybean yield. The objective of this study was to identify novel quantitative trait loci (QTL) for LA, LS and SLW in a recombinant inbred line (RIL) population. The phenotype data were collected in 2011 and 2012 for 93 F_7:10 RILs using a randomized complete block design with 2 replicates each year. Five hundred and sixteen single‐nucleotide polymorphism (SNP) markers and the phenotype data were used to detect QTL using single marker analysis (SMA) and composite interval mapping (CIM). Single markers analysis identified 26 QTL for the three traits, of which 17 were novel and the rests were previously reported QTL. Most of these QTL were also identified by CIM. Most QTL reported in this study were in close proximity (<1 cM) of one or more SNP markers. These publicly available SNP markers with close linkage to LA, LS and SLW should be useful for marker‐assisted breeding for these traits.