春小麦竞争能力与产量的关系

采用deWit替代系列实验确定了4个春小麦品种混播时的竞争能力与单播产量之间的关系。4个春小麦品种竞争能力由强到弱的排序依次为定西-24、和尚头、陇春-8139和高原-602。各品种单播时产量由高到低的排序依次为现代品种定西-24、陇春-8139、高原-602与地方品种和尚头。该结果表明,以优化个体适合度为目标的自然选择,导致个体竞争能力提高、繁殖分配下降,因而产生‘生长冗余’及群体表现下降。现代小麦育种通过降低竞争能力,剔除生长冗余,可以提高小麦单位面积产量(如地方品种和尚头与现代品种高原-602和陇春-8139的比较)。然而,如果现代小麦育种可以同时提高收获指数和地上生物量(如现代品种定西-24与陇春-8139和高原-602的比较),那么具有相对较高竞争能力的品种仍然可望获得较高产量,其前提是具有较高竞争能力的育成品种有着较高的收获指数。因此,春小麦品种的个体竞争能力并不必然地与产量相关,当选育的品种可以使竞争能力与收获指数同步提高,或者伴随着竞争能力的提高,收获指数具有更大幅度的提高,仍然可以获得高产。半干旱地区作物育种应集中于收获指数和地上生物量的同时提高。     

灌浆期水分亏缺条件下二、四、六倍体小麦收获指数和水分利用效率的演化

为揭示不同倍性小麦生长发育、产量性状及水分利用对灌浆期水分亏缺响应的差异,选用二倍体野生一粒小麦(Triticum boeoticum)、栽培一粒小麦(T.monococcum),四倍体野生二粒小麦(T.dicoccoides)、栽培二粒小麦(T.dicoccon),和两个普通六倍体小麦(T.aestivum)品种‘长武134’和‘陕253’6个小麦品种作为供试材料。采用盆栽控水的方法,测定和分析了不同灌浆期土壤水分条件下小麦株高、旗叶叶面积、穗长、根干重、地上生物量、根冠比、千粒重、粒数、产量、收获指数、蒸腾耗水量和水分利用效率等性状的变化。在小麦染色体倍体由二倍体向六倍体进化的过程中,小麦地上生物量、千粒重、穗粒数、产量、收获指数和水分利用效率都显著增加。随着土壤水分从正常→中度亏缺→重度亏缺的减少,收获指数先增大后减小,分别为41.26%、42.48%和38.19%;生物量水分利用效率逐渐增大,分别为2.39、2.43和2.53g·kg–1;产量水分利用效率分别为1.05、1.10和1.04g·kg–1。在灌浆期水分条件是影响收获指数和水分利用效率的关键因素之一。灌浆期的水分亏缺有利于六倍体小麦的收获指数和四倍体的生物量水分利用效率的提高。中度的水分亏缺有利于四倍体和六倍体产量水分利用效率的提高。     

二倍体、四倍体和六倍体小麦产量及水分利用效率

试验选用了6个不同染色体倍性的小麦进化材料（3个二倍体、2个四倍体和1个六倍体）,分别在不同水肥条件下研究其根系、地上生物量、产量、蒸腾耗水量和水分利用效率等指标,旨在阐明小麦进化材料产量及水分利用效率的差异及水肥条件对这些特性的影响。试验表明：不同倍性小麦进化材料的生物量、产量和水分利用存在显著的差异,而且水肥条件对其有显著影响。在染色体倍性由2n→4n→6n的进化过程中,小麦根系及地上生物量均先增加后降低,而产量却显著增加,这与收获指数的增加有关。小麦产量的大小顺序为：T.aestivum〉T.dicoccum〉T.dicoccoides〉Ae.squarrosa〉Ae.speltoides〉T.boeoticum。水分亏缺显著降低小麦的生物量、产量和收获指数;在不同水分条件下,增加施肥量有利于这些指标的增加。但是水分亏缺下,增加施肥却降低各小麦材料的根系生物量。随小麦的进化,蒸腾耗水量显著降低,这与其生育期缩短有关;而生物量水分利用效率和产量水分利用效率却显著升高,且后者的差异要大于前者。各小麦产量水分利用效率的大小排序与产量的完全一致。水分亏缺处理显著减少各小麦进化材料的蒸腾耗水量47％～52％,而显著增加生物量水分利用效率3％～40％;但水分亏缺对产量水分利用效率的促进作用却随染色体倍性的增加而降低,甚至降低六倍体小麦T.aestivum的产量水分利用效率19％。不同水分条件下,高肥处理均有利于蒸腾耗水量、生物量水分利用效率和产量水分利用效率的增加。     

半干旱黄土高原地区地膜覆盖和底墒对春小麦生长及产量的影响

在年均降水量为415mm的半干旱地区黄绵土旱地上,以春小麦为供试作物进行大田实验,研究不同底墒(包括低底墒、中底墒和高底墒)下．地膜覆盖(包括不覆膜、播种后覆膜30d、覆膜60d和覆膜120d即全程覆膜)进程对作物生产的影响。结果表明．增加底墒和合理的覆膜进程均会显著增加作物的生长和产量,但底墒不同,其最佳覆膜进程不同：在低底墒时,覆膜处理反而使产量低于不覆膜处理;在中底墒时．覆膜30d产量最高,随着覆膜时间延长．产量呈下降趋势,甚至全程覆膜产量低于不覆膜处理;高底墒以覆膜60d产量最高。综合作物生长和产量,全程覆膜并没有多少实际意义。在同种覆膜处理下,随着底墒的增加,根生物量、地上干物质、叶面积及产量也增加显著,高底墒覆膜60d处理的产量在所有处理中为最高。     

栽培模式、施氮和品种对冬小麦冠层结构和产量的影响

在黄土高原南部半湿润易早区土垫旱耕人为土上进行大田试验,研究氮肥、品种和栽培模式对冬小麦叶面积指数（IAI）和透光率（DIFN）及产量的影响。结果表明,小麦生长过程中IAI先增大后减小．在开花期最大。成熟期最小。施氮能够显著增加IAI;DIFN的变化规律与LAI相反。不同品种间IAI和DIFN差异显著。全程覆膜和覆膜150d的LAI极显著大于常规栽培、集雨面栽培和三密一稀栽培模式,DIFN与此相反;施氮后籽粒产量极显著增加。在不同栽培模式下,以全程覆膜、覆膜150d和集雨面栽培模式的产量较高,但从维持土壤质量角度考虑,则覆膜150d和集雨面2种栽培模式优于其它几种栽培模式;从冠层结构特征分析,这2种栽培模式更有利于增加群体光合能力。     

黄腐酸拌种对春小麦产量和水分利用效率的影响

在大田研究了黄腐酸拌种对春小麦产量形成和水分利用效率的影响。实验设４个处理：对照（ＣＫ）,播种前种子不处理;ＦＡ处理：播种前用ＦＡ拌种;ＷＭ处理：浇３０ｍｍ底墒水,覆膜;处理ＷＭＦＡ：浇３０ｍｍ底墒水,覆膜,播种前用ＦＡ拌种。２个覆膜处理均在播种后６２ｄ揭膜。同ＣＫ相比,ＦＡ拌种后,根系生长良好,吸收利用了更多的土壤水分,增加了穗重、单穗籽粒重和收获指数,产量和水分利用效率均显著提高。ＷＭ和ＷＭＦ     

施肥和覆膜垄沟种植对旱地小麦产量及水氮利用的影响

通过大田试验研究了施肥和覆膜垄沟种植对旱地冬小麦群体动态、产量构成及水氮利用的影响。结果表明,覆膜垄沟种植和追肥处理可显著提高旱地冬小麦穗数,追肥处理可减少后期无效分蘖;覆膜垄沟种植和追肥处理产量分别比农户模式提高了11.73%和13.91%,穗数和穗粒数是其产量提高的关键因素;覆膜垄沟种植方式可减少土壤水分损耗,水分利用率为11.60 kg · hm^-2 · mm^-1,显著高于其他处理;追肥处理能有效促进小麦生育中后期对氮素的吸收利用,在基施氮量165 kg/hm²上再追肥30 kg/hm²,地上部分吸氮总量增加15.45 kg/hm²,追肥氮的利用率显著高于底肥氮利用率,为51.5%。     

野生和栽培滇龙胆草生物量分配及异速生长

植物地上-地下生物量分配反映了植物的生长策略。草本植物地上-地下生物量是否是等速生长还有争论。养分和密度会影响药用植物地上-地下生物量的分配。本研究比较了野生和栽培滇龙胆草地上-地下生物量分配的差异,分析了栽培年限和密度对栽培滇龙胆草生物量分配的影响。结果表明,野生与栽培滇龙胆草地上-地下生物量分配存在显著差异(P0.05),可能与土壤营养水平和竞争强度有关,但地下生物量和地上生物量为近等速生长关系。密度、密度与生长年限的交互作用均对地下生物量有显著影响(P0.05)。滇龙胆草栽培时需控制密度并研究施肥和土壤微生物等因素对其药用部位产量(地下生物量)的影响。     

羊草种群生物量分配动态模拟

基于4种密度羊草种群的温室模拟试验,分析了羊草种群地上生物量与地下生物量的动态变化．结果表明：羊草种群的地上生物量与地下生物量随生长期呈增加的趋势,且随密度的增加而增加,但不同密度间羊草地上生物量与地下生物量的相对生长速率没有显著差异;不同密度羊草种群的根冠比随生长进程而增加,但差异不显著,表明环境因子是影响羊草种群根冠比变化的主导因素;单株羊草及羊草种群的地上生物量和地下生物量间存在显著的幂函数关系,但幂函数指数与系数随羊草密度的变化而变化,表明资源竞争引起的微环境差异导致了羊草种群根冠比的动态变化,可为定量研究光合产物分配提供参考．     

水曲柳苗木地下竞争与地上竞争的定量研究

对3种密度进行栽培试验,利用通径分析的方法,研究了水曲柳地下竞争和地上竞争的关系及对总竞争的影响。结果表明,水曲柳苗木的地下部分生物量、地上部分生物量和总生物量与营养空间有密切关系。随着苗木空间距离增加,由生物量计算的竞争指数下降。在同一密度条件下,地下竞争指数明显大于地上竞争指数。由于地下生长与地上生长的相互作用,各竞争指数之间具有明显的相关性。但是地下竞争和地上竞争对总竞争的影响是不同的,通径分析可以定量的区分地下竞争和地上竞争的相对大小。地下竞争对总竞争的直接作用范围在0．5543～0．7426之间,明显大于地上竞争对总竞争的直接作用(0．2851～0．5282)。随着距离的增加,单株苗木的生长空间加大,地上部分的竞争作用增加,地下部分的竞争程度减弱。但是,地下根系的竞争在水曲柳苗木总的竞争中占有重要地位。     

Survival and duration of development of Oscinella spp. (Diptera: Chloropidae) on different Gramineae in the laboratory

The duration of development and survival of Oscinella frit, O. nitidissima and O. nigerrima at different growth stages of several plant species was investigated in the laboratory. The effect of the infestation on the growth of plants was also quantified. Survival of O. frit larvae was significantly lower (P < 0.01) on barley than on either oats or wheat, between which there was no significant difference. Survival was usually highest when plants were infested at the two-leaf stage and lowest when plants were infested at the five-leaf stage. The duration of development of both male and female O. frit was longer on barley than on either oats or wheat and generally increased when older plants were infested. The proportion of male flies was greatest when older plants were infested. Duration of development and survival of O. frit was similar on oats and Lolium multiflorum, but larvae did not survive on Dactylis glomerata. Of the other Oscinella species, O. nitidissima larvae did not survive on oats, wheat and barley and O. nigerrima larvae did not survive on either oats or barley. The main shoots of cereal plants infested at the two-, three- or four-leaf stages were rapidly killed by O. frit larvae whereas many of those infested at the five-leaf stage continued to grow slowly. In response to attack proportionately more tillers were produced by oat plants than by either wheat or barley plants. When cereals were infested with O. nigerrima larvae the central shoots were damaged, but most recovered and continued to grow. Damage symptoms were most obvious when cereals were infested at the two-leaf stage, oats being more severely affected than either wheat or barley.     

Competition of wild oat with wheat in comparison to the wheat itself

In a glasshouse experiment, an increase of the number of wheat plants per pot caused the plants to became taller, have more ears and a greater grain yield per pot, while the number of tillers decreased and the straw mass did not change. The N and P contents in straw and N in grain also trended to decrease, while the translocation of these nutrients to the grain increased. The increase of wild oat plants (Avena sterilis spp.macrocarpa Mo.) per pot, produced a decrease of the growth attributes, grain yield and N accumulation in grain of wheat per pot. Wild oat competition with wheat was higher than the wheat competition with itself. Such competition affected the height, number of tillers and ears, the fertility index of the shoots, the straw and grain mass, and the total accumulation of N, P and K nutrients per wheat plant.     

Effects of plant growth regulators on tiller bud outgrowth in uniculm cereals

Plant growth regulators were applied either to seeds or to leaves of uniculm selections of barley and wheat. None of the treatments stimulated the growth and development of tiller buds in the barley selection. In contrast, in wheat the development of tiller buds was readily stimulated and tillers were produced following treatment with Terpal, Cerone, TIBA or nitrate. In Terpal and Cerone treated plants, the stimulation of tiller bud outgrowth and tillering was accompanied by a marked retardation of growth in the main shoot. The growth of the tillers was however not sustained in any of the treatments, and so at maturity all plants were virtually uniculm. The results are discussed in relation to the different overall response of the two species, the death of tillers, and the hormonal regulation of tiller bud development.     

High productivity of wheat intercropped with maize is associated with plant architectural responses

Mixed cultivation of crops often results in increased production per unit land area, but the underlying mechanisms are poorly understood. Plants in intercrops grow differently from plants in single crops; however, no study has shown the association between plant plastic responses and the yield advantage. Here, we assessed the productivity of wheat–maize intercropping as compared to sole wheat and sole maize, and the associated differences in wheat shoot and leaf traits. In two field experiments, intercrop wheat and maize were both grown in alternating strips consisting of six rows of wheat and two rows of maize. The traits of wheat plants in border rows of the strips were compared to the traits of plants in the inner rows as well as those in sole wheat. Leaf development, chlorophyll concentration and azimuth, as well as the final leaf and ear sizes, tiller dynamics of wheat and yield components of both crops were determined. The relative densities of wheat and maize in the intercrop were 0.33 and 0.67, respectively, but the corresponding relative yields compared to the respective monocultures were 0.46 for wheat and 0.77 for maize. Compared to wheat plants in the inner rows of the intercrop strips as well as in the monoculture, border‐row wheat plants in the intercrop strips had (a) more tillers owing to increased tiller production and survival, and thus more ears, (b) larger top leaves on the main stem and tillers, (c) higher chlorophyll concentration in leaves, (d) greater number of kernels per ear and (e) smaller thousand‐grain weight. Grain yield per metre row length of border‐row wheat was 141% higher than the sole wheat, and was 176% higher than the inner‐row wheat. The results demonstrate the importance of plasticity in architectural traits for yield advantage in multispecies cropping systems.     

冬小麦(Triticum aestivum)分蘖冗余生态学意义以及减少冗余对水分利用效率的影响

通过盆栽试验,以旱作冬小麦(Triticum aestivum)为材料,分别在拔节和抽穗期对分蘖进行人工干扰,来模拟不可预测的自然干扰,对冬小麦分蘖冗余的生态学意义以及减少这些冗余对水分利用效率影响进行研究.设置3个处理:从拔节期开始剪去所有小的分蘖,仅保留主茎和一个大的分蘖(A);在拔节期剪去主茎和两个大的分蘖,保留所有小的分蘖(B);在孕穗期剪去主茎和有效分蘖,保留无效分蘖(C).没有被干扰的植物作为对照(CK).通过花期测定叶片的叶绿素含量、叶绿素荧光参数、气孔导度和蒸腾速率等生理指标来评价植物的生理与生化活性.结果显示,在拔节期和抽穗期去除主茎和大蘖后,无效分蘖的生理活性被激活,开始执行有效分蘖的功能.到花期时,这些无效分蘖已经在生理活性上满足了补充和替代有效茎的要求.虽然株高和穗的整齐度、穗数和产量显著下降,但并没有防碍小麦的繁衍子代,因此,正是这些由早期"无效分蘖"补充而来的有效茎,避免了小麦绝种的风险.而在拔节期去除无效分蘖后,对小麦产量没有显著影响,但提高了水分利用效率,和对照相比水分利用效率提高了10%.因此,可以认为小麦在分蘖上存在着对水分利用不利的生长冗余,减少这些冗余有望节约用水、提高作物的水分利用效率.     

9个小麦品种(系)比较试验中的主要农艺性状

目的:通过对9个小麦品种(系)的比较试验中的主要农艺性状统计分析,筛选出比较适宜现阶段在贵阳地区乃至贵州省栽培的高产优质小麦品种(系)。方法:9个小麦品种(系)在试验地里随机区组排列,3次重复,记录小麦的全生育期,出苗数,田间生育期,株高,有效分蘖数,每株干重,穗长,穗粒重等,并在Excell上进行统计分析。结果:全生育期在200天左右,出苗数有3个超过100万/ha,最低只有44．8万/ha,株高在50 cm以上的有6个品种(系),3个在40 cm-50 cm之间,有效分蘖数400万/ha以上的有3个,最低的是199．1万/ha,每株干重最高是8．5 g,最低是5．7 g,穗长整齐度除98-22外都优于对照,经LSR法测验表明,贵农15,黔98353,黔麦15分别与夏繁29,98-28,贵单5号,黔98284-82,黔0110都达到差异显著水平,贵农15,黔98353,黔麦15分别与98-22达到差异极显著水平,其余的差异皆不明显。结论:可以初步得出贵农15,黔98353,黔麦15目前可以作为在贵阳地区推广种植的较优品种(系)。     

Structural development and stability of rice Oryza sativa L. var. Nerica 1

The structural development of glasshouse-grown rice Oryza sativa L. var. Nerica 1 was studied in relation to its stability against lodging. The morphology and mechanical properties of both the stem and roots were examined from tillering, 4 weeks after transplantation up to maturity, together with plant weight distribution and anchorage strength. The "factors of safety" against root and stem failure were subsequently calculated throughout development. Rice plants showed similar morphology to wheat, although they possessed around twice as many tillers per plant and 10 times as many coronal roots. The mechanics of anchorage were also similar. The strength and rigidity of individual tillers increased throughout development as the plants grew taller and heavier and were around 15 times greater than in wheat. By contrast, individual root bending strength, the number of roots, and the anchorage strength levelled off earlier, and anchorage strength was only around twice that in wheat. Consequently, while the self-weight safety factor against stem failure was much higher than in wheat, increasing until late on in development from around 30 to 150, the self-weight safety factor against root anchorage failure was similar to wheat, decreasing from around 15 to 5. Consequently, plants subjected to anchorage tests always failed in their root system rather than their shoot system. The results suggest that, in the field, rice plants would be more likely to undergo root lodging than stem lodging, and that breeding efforts to reduce the incidence of lodging should act to strengthen the rather weak coronal roots.     

A new selection criterion for yield in wheat

Summary The mortality of young tillers to an extent of 36.5% under optimum cultural conditions was recorded in a field experiment. Attention is drawn to the necessity of minimising this loss and to diverting it towards productive tillers by applying selection pressure. Future yield advances may be achieved by selecting genotypes which tiller moderately in the vegetative phase, most of which survive to produce grains. The character association of each variety under consideration was studied for the suitability towards this objective. A modified selection procedure is suggested which may be advantageously applied to achieve this objective. The proposed new methodology may also be effectively applied to such other cereal crops as barley, triticale and oats.     

Insights on the role of tillering in salt tolerance of spring wheat from detillering

Tillering is reduced by salinity, with the primary and secondary tillers being more affected than is the mainstem. To understand the importance of tillering in the salt tolerance of wheat plants, two contrasting genotypes of spring wheat (Triticum aestivum L.) were grown in a greenhouse under saline or non-saline conditions and were subjected to five progressive levels of detillering. Regardless of the genotype and salinity, shoot dry weight, seed yield and seed number per plant were all significantly decreased in the treatments where only one or two tillers per plant remained compared with the untouched treatment (more than three tillers), whereas these same variables per tiller tended to be increased on a per tiller (mainstem or substem tiller) basis. The increased seed yield per tiller observed with tiller reduction may be attributed to the enhanced seed number within the spikelet. Under saline conditions, the reductions in shoot dry weight, seed yield and seed number per plant for the salt-tolerant genotype Kharchia were of a greater magnitude in the treatments where only one or two tillers per plant were present compared with the untouched treatment, whereas the magnitude of this reduction in the salt-sensitive genotype Sakha 61 was decreased.