Ontogenetic analysis of yield components and yield stability of durum wheat in water-limited environments

Summary One main reason for the slow improvement of durum wheat in water-limited environments is the lack of clear understanding of the interrelationships among yield components and their compensatory changes under low and erratic moisture availability. Five cultivars, varying in many physiological attributes, were tested under different drought-stress conditions in field and greenhouse experiments. The cause-effect relationships of duration of vegetative period, duration of grain-filling period, number of spikes per m², kernels per spike, kernel weight and grain yield per m² were assessed. Furthermore, yield stability was evaluated. Yield reduction was largest under mid-season stress (58%), followed by terminal stress (30%) and early stress (22%). Cultivar Po was very sensitive to terminal stress.Path-coefficient analysis revealed a complex pattern of relationships among the six variables. An increase in vegetative period reduced the grain-filling period under all conditions. It increased number of kernels per spike under non-stress conditions. The direct effect of spikes per m² on grain yield was significantly positive. However, more spikes per m² resulted in fewer kernels per spike and a low kernel weight and, as a result, a negative relationship with grain yield under early stress. Grain-filling period had a strong influence on grain yield via kernel weight. Kernels per spike had the largest direct effect on grain yield. However, it was negatively correlated with kernel weight, especially under terminal stress. Grain yield heavily depended on kernels per spike under early stress and grain-filling period and kernels per spike under terminal stress.Variation in drought susceptibility index among cultivars was significant under early and terminal stress conditions, but not under mid-stress conditions. Yield potential and stability were not correlated for the different drought-stress conditions.Longer grain-filling period, increased number of kernels per spike and limited spike number per m² can be used as selection criteria for sustainable yield in water-limited environments.     

小麦收获指数与主要农艺性状的相关性探析?

小麦收获指数是指籽粒产量占地上部生物产量的百分率。研究小麦品种主要农艺性状和经济性状间与其产量的相互关系,采用相关性分析与回归方法,对影响收获指数的10个主要农艺性状及因素进行了研究分析。结果表明：供试小麦HI具有较大的改良空间;HI与穗颈长、株高、穗长、小穗数、主茎生物产量有显著负相关,与单穗质量、产量呈正相关,与生物产量没有显著相关性;主成分分析结果显示,3个主成分累积贡献率达 87.427%,表明 3 个主成分已覆盖所有性状的主要信息;通过回归分析,小麦HI与单穗籽粒产量、生物产量、千粒质量有显著回归关系。结论: 通过对10份小麦材料农艺性状的统计分析,得出如下结论。HI受单穗质量、生物产量、千粒重影响较为明显有显著回归关系,与单穗质量、产量和穗粒数有明显正效应,生物产量对其有负效应。小麦HI提高可通过选育生物产量不宜过大,而穗粒数较高、单穗重较大的小麦品种。     

Harvest Index and Spike Index in Crosses between Wheat Genotypes with Different Spike Architecture

Crosses between vulgare wheat genotypes with different spike architecture were examined for total biomass per plant, grain mass per plant, and harvest index. The genotypes with branched spikes (turgidum type) and tetrastichon spikes were equal or superior to those with normal spikes in total biomass per plant but inferior in grain mass per plant. Consequently, they had significantly lower harvest indices. In the F₁ and F₂ generation, high heterosis for total biomass per plant occurred in all crosses between the genotypes with branched and normal spikes. There was heterosis for grain mass per spike in most crosses, but it was not as high as for total biomass. This investigation confirmed earlier findings that genetic changes towards the branched or the tetrastichon spike do not increase the potential for grain yield. Since, however, the crosses between the genotypes with branched and normal spikes showed high heterosis for grain mass per plant, lines with highly fertile but normal spikes may be expected in the segregating generations as a result of a genetic change in sink capacity. The genotypes with branched and tetrastichon spikes produced higher biomass per spike but lower spike index than the genotypes with normal spike. This may be an indication that the increase in vegetative area of the spike does not necessarily have a positive effect on grain mass per spike.     

不同生育阶段气象因子对玉米产量及构成要素的影响分析

为揭示气象因子对玉米产量构成要素的影响机理,以‘吉单27’为试验材料,于2012、2013年在佳木斯市农业气象试验站进行分期播种试验,通过调整播期改变玉米生育期内的气象条件,分析产量及产量构成要素与气象因子的关系,为抵御阶段性不良气象因子的胁迫并实现玉米高产提供理论依据。结果表明：产量构成要素与不同生育阶段的多个气象因子显著相关。拔节至大喇叭口期日均降水量为玉米产量的限制因子,通过影响秃尖比、穗粒数和株粒数重影响产量;吐丝至乳熟期温度为限制因子,该生育期随着日平均气温、日均最高温度、日均最低温度的升高,秃尖比减小,穗粒数、株粒数重均增加;大喇叭口至抽雄期,日照时数与秃尖比呈显著负相关,此期随着日照时数的增加秃尖比减小;乳熟到成熟期,日均相对湿度影响穗粒数、株粒数重的提升。‘吉单27’在佳木斯的最佳播种时间为5月上中旬,6月下旬至7月上旬的日均降水量,7月下旬至8月上旬的日平均气温、日均最高温度、日均最低温度成为玉米产量提升的限制因子,在试验设定的密度条件及栽培管理水平下,产量提升主要受穗粒数的制约。     

The 1BL/1RS chromosome translocation effect on yield characteristics in a Triticum aestivum L. cross

Comparisons involving 28 random F₂-derived F₆ wheat (Triticum aestivum L.) lines from the cross, ‘Nacozari’/‘Seri 82’, suggested that advanced derivatives with the 1BL/1RS chromosome translocation possess superior agronomic performance in both full and reduced irrigation conditions when compared with 1B derivatives. This performance advantage was attributed to high grain yield, above-ground biomass at maturity, grains/spike, 1000-grain weight and test weight. The 1BL/1RS lines were shorter with delayed flowering and maturity. The superiority of the 1BL/1RS translocation group on grains/m² was expressed only under the full irrigation environment. Higher harvest index, longer spike-length and grain-filling period were detected only under reduced irrigation conditions. A significant grain yield relationship with test weight was detected only among the 1BL/1RS genotypes, indicating that they possess heavier and plumper grains than the 1B genotypes.     

Introgression of resistance to late blight (Phytophthora infestans) from Solanum pinnatisectum into S. tuberosum using embryo rescue and double pollination

In order to investigate the agricultural potential of the genus Vicia, and identify traits associated with productivity and responsiveness to environment, 34 undomesticated Mediterranean accessions representing Section Narbonensis (V. johannis, V. narbonensis) and V. sativa were grown in five contrasting environments in northern Syria (growing season rainfall: 76–290 mm).Highly significant genotype × environment interactions were observed for all traits. For most of the components of yield, accession mean performance (productivity)was highly correlated with responsiveness across environments (r = 0.59–0.96), as defined by joint linear regressions. Thus high yielding genotypes tended to be relatively more productive than low yielding genotypes under conditions that favoured high yields. Regression analysis revealed that mean site yields were positively correlated to rainfall (r = 0.85) and its attendant effect on growing season length as measured by cumulative season temperature and phenology (r = 0.59–0.81).In order to examine yield related traits independently of taxonomy, genotypes were grouped into three categories using K-means clustering based on productivity and responsiveness of seed, hay and biological yield. Highly productive/responsive genotypes were tall with high harvest index, large seeds and low fecundity (seeds and pods per plant), whereas unproductive/unresponsive plants tended to be short, highly fecund, with small seeds and low harvest index. Principal components analysis showed that responsiveness, in terms of seed, hay and biological yields, was closely related to phenological plasticity. Thus highly productive/responsive genotypes were able to start flowering earlier than unproductive/unresponsive genotypes in early environments, but significantly later in late, higher rainfall environments. Plant growth habit was also related to yield responsiveness. In environments with little biomass production the proportion of erect plants was high in all three categories. In more favourable, high biomass environments, the proportion of erect plants in unproductive/unresponsive genotypes fell dramatically, but was unchanged among productive/responsive genotypes. We suggest that for unproductive/unresponsive genotypes competition for light is increased under optimal growth conditions. We argue that the optimal combination of fixed and responsive traits in high yielding genotypes results in a `compound interest-type' response to more favourable environments. Highly productive and responsive genotypes can capture resources more effectively than their low yielding counterparts, leading to a positive relationship between performance and responsiveness for most components of yield. Differences in productivity and responsiveness for seed, hay and biological yield reflected Vicia taxonomy, increasing in the following order from low to high: V. johannis, V. sativa, the small seeded V. narbonensis (salmonea, jordanica, affinis) V. n. var. narbonensis, and finally V. n. var.aegyptiaca. V. n. var. aegyptiaca showed the most agricultural potential, since the taxon contained all the properties of productive/responsive genotypes listed above, yielding >1 t/ha under extremely arid conditions (104 mm),and >2.5 t/ha on 290 mm rainfall, confirming its potential for dry environments. This revised version was published online in August 2006 with corrections to the Cover Date.     

QTL for yield, yield components and canopy temperature depression in wheat under late sown field conditions

A wheat (Triticum aestivum L.) recombinant inbred line (RIL) population was used to identify quantitative trait loci (QTL) associated with yield, yield components, and canopy temperature depression (CTD) under field conditions. The RIL population, consisting of 118 lines derived from a cross between the stress tolerant cultivar ‘Halberd’ and heat stress sensitive cultivar ‘Karl92’, was grown under optimal and late sown conditions to impose heat stress. Yield and yield components including biomass, spikes m^?2, thousand kernel weight, kernel weight and kernel number per spike, as well as single kernel characteristics were determined. In addition, CTD was measured during both moderate (32–33 °C) and extreme heat stress (36–37 °C) during grain-filling. Yield traits showed moderate to high heritability across environments with a large percentage of the variance explained by genetic effects. Composite interval mapping detected 25 stable QTL for the 15 traits measured, with the amount of phenotypic variation explained by individual QTL ranging from 3.5 to 27.1 %. Two QTL for both yield and CTD were co-localized on chromosomes 3BL and 5DL and were independent of phenological QTL. At both loci, the allele from Halberd was associated with both higher yield and a cooler crop canopy. The QTL on 3BL was also pleiotropic for biomass, spikes m^?2, and heat susceptibility index. This region as well as other QTL identified in this study may serve as potential targets for fine mapping and marker assisted selection for improving yield potential and stress adaptation of wheat.     

Evaluation of heat stress tolerance in irrigated environment of T. aestivum and related species. I. Stability in yield and yield components

Wheat production is often limited by continual or terminal heat stress. The current study was aimed at the characterization of wild relatives and cultivated Triticum species for their heat tolerance in yield and its analysis in relation to yield components which confer yield stability at the three ploidy levels. Thirty-two non-cultivated and cultivated genotypes belonging to diploid, tetraploid and hexaploid wheat species were evaluated for heat stress tolerance in the field under full irrigation. Wheat species were sown in the field(New Delhi, India; 77°12′E, 28°40′N, 228.6 m m.s.l) at two dates of sowing, November (normal) and January (late Sowing) during winter seasons of 1994–95 and 1995–96. The late sown crop experienced 3°C warmer temperatures than that of the normal sown crop. Wide variability was observed for grain yield stability under heat stress, as the heat susceptibility index (S) ranged from 0.13 to 2.08. Hexaploidy conferred the productive and adaptive advantages as it combined high yield and stability when compared to the tetraploid and diploid groups. However within each ploidy group wide variation was observed for heat tolerance. T. aestivum cv C306 & HI1136, T. dicoccoides, T. monococcum acc. BSP1 and Ae. speltoides ssp. liqustica were highly heat tolerant in their grain yield. Stability in grain no. m- 2 conferred yield stability in all three ploidy levels, although grain weight stability also contributed to yield stability in moderately stable T. turgidum and T. sphaerococcum under heat stress. Higher biomass and grain no. m-2 are the two important traits which could be considered potential selection criteria for yield under heat stress. Of the two components of grain no. m-2, stability in spike no. m-2could be considered more important trait than grain no. spike-1. Since wide variation for heat tolerance of all the yield components are available among the wheat species, these species can be used for improving specific yield components of cultivated wheat. This revised version was published online in July 2006 with corrections to the Cover Date.     

Reduction in kernel weight as a potential indirect selection criterion for wheat grain yield under terminal heat stress

Heat is an important abiotic stress during wheat (Triticum aestivum L.) grain‐filling in South Asia. A study was undertaken to determine effectiveness of selection for reduction in 1000‐kernel weight (TKWR) under heat stress to increase grain yield. Selection was made for low and high TKWR and selected progenies were evaluated in timely and late seeded trials at two locations in Nepal in 2003. One thousand kernel weight (TKW), biomass yield, grain yield, harvest index (HI), grain‐filling duration (GFD) and area under spot blotch progress curve per day (AUDPC/day) were examined. The low and high TKWR groups did not differ significantly for TKW, biomass yield, grain yield, HI, days to heading, GFD and AUDPC/day under timely seeding. However, low TKWR lines showed higher TKW, biomass yield, grain yield, HI, and GFD and lower AUDPC/day than the lines with high TKWR under late seeding. Realized heritability estimates for TKWR ranged from 0.68 to 0.85. The findings show that selection for low TKWR could be used as an indirect selection criterion to identify high grain yielding lines under terminal heat stress.     

不同水分条件下小麦持绿表型性状评价及其与产量相关性研究

找出适宜在多个环境条件下评价小麦持绿性状的表型指标,为快速筛选小麦持绿品系,加速抗旱、高光效育种进程提供数据支撑。以包含306个家系的RIL群体（旱选10号×鲁麦14）为材料,分析了不同水分条件下灌浆不同时期旗叶叶绿素SPAD值、功能绿叶面积持续期（GLAD）以及衰老参数变化特征,并对其与产量性状的相关性进行了研究。结果表明：RIL群体SPAD值、GLAD在整个灌浆期的变化动态复杂,衰老相关参数无法反映其动态变化过程。2种水分条件下,在灌浆后期（花后20、25和30d）SPAD值与粒宽、粒厚、千粒重以及单株产量呈显著或极显著正相关。在灌溉条件下花后10、13、16、19和22d的GLAD与单株产量呈极显著正相关;而在干旱胁迫条件下GLAD与单株产量相关性则未达到显著水平。不同环境条件下,旗叶SPAD值在灌浆后期（花后20、25和30d）相比于GLAD和衰老特征参数与产量性状具有更好的相关性,且测定相对简单,更适宜于持绿品系的快速筛选。     

播期和种植密度对超高产小麦济麦22产量及其构成因素的影响

为给‘济麦22’大面积推广提供适宜栽培措施,选择4个生态区5个试验点,通过大田试验研究了播期和种植密度对该品种产量及其构成因素的影响。结果表明,播期对单位面积穗数、千粒重及产量产生显著的影响,但对穗粒数影响不大;种植密度对产量及构其成因素均有显著影响。在一定范围内,‘济麦22’单位面积穗数随着播期的推迟而减少,随密度的增加而增加;穗粒数随播期的推迟而增加,随密度的增加而减少;千粒重随播期的推迟先增加后下降,随密度的增加而降低。产量构成因素稳定性分析发现环境差异对‘济麦22’千粒重影响较大,而对单位面积穗数和穗粒数影响较小。2008年4个生态区‘济麦22’适宜播期范围分别为：鲁南地区10月8日至14日、鲁东地区10月6日至12日、鲁北地区10月1日至7日、鲁西地区10月10日至16日;适宜种植密度范围为180×104/hm2~240×104/hm2。研究还表明,在中高肥或高肥地力条件下,增加粒重对充分发挥‘济麦22’高产潜力似乎更有效。因此,选择适宜播期播量的同时,应在栽培技术中注意采取相应的措施,获得足够的单位面积穗数的基础上,稳步提高粒重。     

Evaluation of grain yield and its components in wheat cultivars and landraces under near optimal and drought conditions

In a 2-years experiment, 30 wheat cultivars and 21 landraces from different countries were tested under near optimum and drought stress conditions. Plant height, number of sterile spikelets per spike, spikelets per spike, number of kernels per spike, kernel weight per spike, 1000 kernel weight and grain yield were evaluated. The number of kernels per spike, 1000 kernel weight and especially yield were more sensitive to drought stress in the cultivars than plant height and number of spikelets per spike, while in the landraces these traits did not differ under drought stress compared to near optimum conditions. The average yield of cultivars was significantly better than the average yield of landraces under near optimum as well as drought stress conditions. Path coefficient analysis showed that for cultivars under near optimum conditions there was no significant direct association of any of the analysed characters with yield, while under drought stress conditions, number of kernels per spike had a significant positive direct effect. Under drought stress conditions, the number of sterile spikelets displayed a negative direct effect, while kernel weight per spike had a positive direct effect on yield. Hierarchical cluster analysis was used as a tool to classify cultivars and landraces according to their yield ability under near optimum and drought stress conditions. Among the cultivars, two groups out of five and among one of three in the landraces were characterised by high yields in both near optimum as well as under drought stress conditions. These genotypes may serve as sources of germplasm for breeding for drought tolerance. This revised version was published online in August 2006 with corrections to the Cover Date.     

不同带状播种方式对冬小麦群体动态和产量结构的影响

试验在大田条件下,设置带状播种（带宽20、40、60、100 cm,行距20 cm）、全区撒播（幅宽270 cm）等播种方式,研究了种子分布带对冬小麦的群体动态、产量以及产量三要素的影响。结果显示：随着播种宽度的增加,穗数和各生育期单株分蘖数均呈逐渐增加的趋势,播种宽度20 cm时,单株分蘖数和穗数最少,全区撒播时单株分蘖数和穗数最多,千粒重和穗粒数的变化趋势与公顷穗数相反,播种宽度20 cm时,千粒重和穗粒数最大,全区撒播时最小。产量则呈先上升后下降的趋势,播种宽度20~60 cm时,增产效果最好,当全小区撒播时,产量最低。综上所述,适当宽幅播种有利于小麦群体生长和产量提高,分蘖成穗率和产量比等行距播种和撒播高,本试验条件下,60 cm宽幅播种分蘖多,成穗率高,产量最高。     

Growth and Yield Response of Facultative Wheat to Winter Sowing, Freezing Sowing and Spring Sowing at Different Seeding Rates

Growth and yield of wheat are affected by environmental conditions and can be regulated by sowing time and seeding rate. In this study, three sowing times [winter sowing (first week of September), freezing sowing (last week of October) and spring sowing (last week of April)] at seven seeding rates (325, 375, 425, 475, 525, 575 and 625 seeds m^?2) were investigated during the 2002–03 and 2003–04 seasons, in Erzurum (Turkey) dryland conditions, using Kirik facultative wheat. A split‐plot design was used, with sowing times as main plots and seeding rates randomized as subplots. There was a significant year × sowing time interaction for grain yield and kernels per spike. Winter‐sown wheat produced a significantly higher leaf area index, leaf area duration, spikes per square metre, kernel weight and grain yield than freezing‐ and spring‐sown wheat. The optimum time of sowing was winter for the facultative cv. Kirik. Grain yields at freezing and spring sowing were low, which was largely the result of hastened crop development and high temperatures during and after anthesis. Increasing seeding rate up to 525 seeds m^?2 increased the spikes per square metre at harvest, resulting in increased grain yield. Seeding rate, however, was not as important as sowing time in maximizing grain yield. Changes in spikes per square metre were the major contributors to the grain‐yield differences observed among sowing times and seeding rates. Yield increases from higher seeding rates were greater at freezing and spring sowing. We recommended that a seeding rate of 525 seeds m^?2 be chosen for winter sowing, and 575 seeds m^?2 for freezing and spring sowing.     

播期和播种密度对周麦18号产量及产量构成的影响

在低(180万株/hm2)、中(270万株/hm2)、高(330万株/hm2)3种播种密度条件下,研究了不同播期对周麦18号产量和产量构成的影响。结果表明,在相同播种密度下,不同播期对小麦产量影响有极显著差异;在相同播期下,不同播种密度对产量影响差异不显著。播期对周麦18号成穗数和千粒重有极显著影响,对穗粒数影响较小。成穗数是决定周麦18号产量的关键因素,但同时也制约穗粒数和千粒重对产量的贡献。保证周麦18号高产的适宜播期为10月8日～10月15日,播种密度范围较广(180万～330万株/hm2),早播适宜低密度,播期推迟,密度适当增加。     

Genetic variation and interrelationships of agronomic characters in landraces of bread wheat from southeastern Iran

There is renewed interest in wheat landraces as important sources of genetic variation for agronomic characters. Fifty-three pure lines of bread wheat (Triticum aestivum L.) derived from seven landraces collected from southeastern Iran were used to estimate genetic variation and heritability for 13 developmental and quantitative characters. Path-analysis was used to partition the genetic correlations between grain yield and six grain yield-related traits. Mean values of landraces were also compared with three improved cultivars from California and Iran. Genotypic differences among the landraces and among the pure lines collected from the landraces were highly significant for all characters considered. Compared with the modern cultivars, the landrace genotypes were, on average, later in days to heading and taller than the cultivars but had lower values for number of grains per spike, 1000-grain weight, grain yield and harvest index. Some landrace genotypes were similar to the modern cultivars for grain yield. Moderate to high genetic variation was displayed by number of grains per spike, number of spikes per plant, 1000-grain weight, and harvest index. The heritability estimates ranged from 59% for grain yield to 99% for days to anthesis. Expected genetic advance (as % of the mean) was ≈34% for number of spikes per plant, number of grains per spike, and 1000-grain weight. Days to heading and to anthesis correlated positively with number of spikes per plant, shoot biomass, and straw biomass but negatively with number of grains per spike and harvest index. The strong direct effect of number of spikes per plant on grain yield was completely counterbalanced by its indirect negative effects via number of grains per spike and 1000-grain weight. Number of grains per spike and 1000-grain weight were positively correlated with grain yield, and they had large direct effects. These two characters, however, were negatively correlated and exhibited a substantial counterbalance effect via one another and via number of spikes per plant. The landraces could be improved by intercrossing the promising genotypes identified in this study, with simultaneous selection for earliness, fewer number of spikes per plant, greater number of grains per spike and heavier grains. For further improvement, crossing programs between the landraces and introduced germplasm may be necessary. This revised version was published online in July 2006 with corrections to the Cover Date.     

冬小麦品种新麦29在不同播期和播量处理下产量形成的影响

筛选出冬小麦较适宜的播期和播量组合以适应冬前积温不断增加的环境变化,以新麦29作为研究对象,于2016～2017年度在河南省辉县市开展播期(10月12日、18日和19日)和播量(基本苗210万、300万和390万／ha)二因素裂区试验,探索不同播期和播量条件下对小麦的产量及其构成因素的影响。结果显示不同播期之间的平均容重是以10月12日显著低于其他两个播期,而随着播量不断增加其平均容重亦随之增加,但差异不显著;相同播期不同播量处理对农艺性状结实小穗数的影响不显著,同时对不孕小穗数则无明显变化规律。播期对穗数、穗粒数、千粒重3个产量构成因素的影响均显著,但对籽粒产量的影响不显著。播量对产量及穗数、穗粒数2个构成因素的影响均呈现出差异水平显著。不同播期和播量互作效应对小麦籽粒产量与单位面积穗数两者均呈现出差异性显著。与播量相比较而言,播期对新麦29产量影响较大。随着播期的不断推迟,新麦29的产量不断下降且10月12日的产量显著高于10月24日的。播量210万/ha与播量390万/ha 之间的平均产量显著差异,但都与播量300万/ha相比差异都不显著。依据不同播期和播量组合的产量分析,最佳播期是10月12日,基本苗300万/ha为较适宜的播量;新麦29的产量潜力在播期10月12日至18日是较为适宜范围,与其对应的适宜播量为基本苗300万～390万/ha得以充分发挥。     

播期对糯玉米籽粒产量及品质的影响

为满足农户对糯玉米种植的不同需求,探讨山西中晚熟地区播期对糯玉米产量与品质的影响。以晋糯18和晋糯20为试验材料,4月26日-7月5日,设置6个播期处理,研究其对产量、穗长、百粒重、穗粒重及籽粒蛋白质、淀粉、粗纤维素及赖氨酸相对含量的影响。结果表明,播期与品种对糯玉米产量及品质都有显著影响。其中B3播期（5月24日）处理下2个糯玉米品种产量、穗长、百粒重及穗粒重都高于其他播期处理,说明糯玉米适宜在小满前后播种。提前播期有利于籽粒蛋白质、赖氨酸相对含量的提高,而推迟播期降低籽粒粗纤维素、赖氨酸相对含量。B1与B6播期下籽粒淀粉相对含量低于其他播期,且B4、B5播期下籽粒淀粉相对含量高于其他播期。说明适当推迟播期有利于籽粒淀粉相对含量的提高,但过早或过迟播种均显著降低籽粒淀粉含量。糯玉米籽粒中粗纤维素含量与品种遗传背景密切相关,且推迟播种后品种差异对籽粒淀粉含量的影响降低。通过相关性分析发现积温、降水量与产量、穗粒重以及赖氨酸相对含量均达到极显著正相关关系,与穗长、百粒重均达到显著正相关关系,说明播期对产量性状及籽粒赖氨酸相对含量有显著影响。在山西中晚熟地区糯玉米在小满前后播种时产量最高,适当提前有利于籽粒蛋白质、赖氨酸含量的提高,适当推迟有利于籽粒粗纤维素、淀粉含量的提高。     

豫西地区冬小麦春播及春麦引种效果简报

基于小麦应变栽培需要,对豫西地区春季播种冬小麦和引进春小麦品种观察分析,结果表明：2月中旬前播种或3月上旬前出苗的豫麦18小麦品种,在豫西地区可收获产量,但产量较低;春小麦产量一般高于春季同期播种冬小麦产量,但应选择成熟早,灌浆快,后期耐高温品种,注意适期早播,提高穗粒重。     

Association of staygreen trait with canopy temperature depression and yield traits under terminal heat stress in wheat (Triticum aestivum L.)

The presence or absence of the staygreen trait was screened for 3 consecutive years in 963 wheat lines from various sources, including Indian and CIMMYT germplasm. Staygreen was assessed at the late dough stage by visual scoring (0–9 scale) and the leaf area under greenness (LAUG) measurement. Around 5.5 % of the lines were staygreen, 10.5 % were moderately staygreen, and the remaining lines showed little or no expression of the trait. One hundred lines showing diversity for the staygreen trait were sown under three different sowing dates (timely, late and very late) for 3 consecutive years in three replications to determine the association of staygreen with heat tolerance. There was a decline in yield, biomass, grain filling duration (GFD) and 1,000 grain weight (TGW) under late and very late sowing conditions owing to terminal stress at anthesis and later stages. However, the decline was relatively less in staygreen genotypes compared to the non-staygreen (NSG) ones. The correlation study showed that LAUG and canopy temperature depression (CTD) were strongly correlated. LAUG and CTD were also significantly associated with grain yield, GFD and biomass. To further confirm the association of the staygreen trait with terminal heat stress, individual F₂-derived F₇ progenies from the cross of the ‘staygreen’ lines with NSG were evaluated for yield and yield traits at the three sowing dates. In each cross, the staygreen progenies showed a significantly smaller decline in yield and TGW under heat stress than the NSG progenies. These results appear to suggest an association between the staygreen trait and terminal heat stress and, thereby, that the staygreen trait could be used as a morphological marker in wheat to screen for heat tolerance.