两春小麦品种竞争能力、水分利用效率及产量关系的研究

用盆栽方法测定了2个春小麦品种－地方品种和尚头与现代品种陇春－8275在5个土壤水分梯度下,单、混播时的水分消耗、水分利用效率、竞争能力和籽实产量。单播条件下,在极低水分条件下（12％）,和尚头有相对较高的产量,在水分条件较好时陇春－8275有较高的产量;在保持各水分处理条件下,地方品种和尚头较之现代品种陇春－8275消耗更多的水分,水分利用效率较低。混播条件下,各尚头有较高生物量、籽实产量及较强的竞争能力,竞争优势不受土壤水分的影响,其表现为高个体生物量品种较之低个体生物量品种消耗更多的水分,陇春－8275受到强烈的抑制,消耗较少的水分及较低的籽实产量。表明进化选择的是竞争能力,而非单播下的产量表现。可以预见,在小麦育种中选育具小根系的对水分弱竞争能力的品种将成为半干旱区今后育种的一个重要方法。     

半干旱区春小麦品种竞争能力与产量关系的研究

 采用de Wit替代系列法研究了黄土高原半干旱雨养农业区传统地方品种(和尚头)与现代品种(陇春8275)之间在混播条件下的竞争结局。在单播条件下现代品种较之地方品种具有更高的产量;但在混播条件下,和尚头具有明显的竞争优势。本项研究结果说明竞争优胜者并非是单播条件下产量性能更佳的品种,即作物品种的竞争能力与生产性能之间存在着负相关关系。形成这种关系的主要原因在于作物群体内个体竞争选择的方向与人类农业生产追求的目标不一致。     

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。     

水分供给对新老两个春小麦品种水分利用效率及籽实产量的影响

大田实验研究了不同的水分供给对和尚头和定西-24的产量及水分利用效率的影响。结果表明:在雨养和中水条件下,和尚头和定西-24的产量和水分利用效率都得到了显著的提高。随着灌溉水量增加,农田的耗水量也会增加,同时,土层贮藏水的消耗量也减少,灌溉水的利用效率逐渐减少。减少灌溉量,提高小麦对土层贮藏水的利用效率是实现小麦高产节水栽培的一种有效途径     

不同水肥条件下两个燕麦品种的竞争关系

采用de Wit取代系列法,探究了不同水肥条件下两个燕麦品种"定燕1号"和"晋燕17号"的竞争关系。结果表明:所有水肥处理中,"晋燕17号"的竞争能力强于"定燕1号";低水低肥和高水高肥条件下,"晋燕17号"的地上生物量高于"定燕1号";随着水肥梯度增加,"定燕1号"和"晋燕17号"的地上生物量中茎比重均增加,叶比重均减少;所有处理中,"晋燕17号"的单播产量和收获指数均高于"定燕1号";"晋燕17号"通过提高地上生物量和收获指数达到高产的目的。竞争能力和收获指数的同步提高有望成为干旱区作物育种的一个关注焦点。     

单播与混播对两个冬小麦品种产量和水分利用效率的影响

选取黄土旱塬两个冬小麦品种长武135和平凉40,采用生态替代法连续两年在田间条件下研究了单播和混播方式对冬小麦产量和水分利用效率的影响.结果表明:单播条件下平凉40单位面积根量为367.60 g·m-2,显著大于长武135的297.31 g·m-2,且其根系在各土层中分布较均匀,表明与长武135相比,平凉40吸收土壤水分的能力较强,但其在单播条件下的产量和水分利用效率较低.混播增加了平凉40和长武135根系在较深土层中的根量分布,两品种根量分别比单播条件下多13.36和8.50 g·m-2,混播增强了小麦根系对深层土壤水分的吸收利用,提高了单位面积总产量,增加了群体水分利用效率.与平凉40相比,长武135分配了更多的干物质到繁殖器官,使其根量和地上营养器官的生物量减小,从而提高了籽粒产量和收获指数,表现出较高的水分利用效率.     

土壤水分对两个冬小麦品种产量和竞争能力的影响

研究了黄土塬区两个旱作冬小麦品种(长武135和平凉40,前者是后者的换代品种)在不同土壤水分条件下竞争能力和产量形成的关系。研究设2种土壤水分条件(土壤含水量为田间最大持水量的75%～80%和40%～45%),采用生态替代法设计了同一播种密度的6个播种比例组合的盆栽试验。低水分单播条件下,长武135具有较高的产量(长武135为27.59g/pot,平凉40为24.91g/pot),而混播条件下平凉40在产量和相对产量上较长武135品种具有明显的竞争优势。高水分条件下,平凉40产量随播种比例的减小下降较快(长武135产量曲线斜率35.468,平凉40为36.237)。平凉40低水分单播时花后干物质积累量较少(长武135为0.67g/pot,平凉40为0.55g/pot),而混播时较多(长武135各比例均值0.58g/pot,平凉40为0.71g/pot),导致了平凉40品种单播时产量较低和混播时产量较高。平凉40地下生物量显著大于长武135(高水分条件下,长武135为10.03g/pot、平凉40为11.51g/pot;低水分条件下二者分别为8.41g/pot和10.69g/pot),且耗水量大(高水分条件下平凉40多耗水2.72kg/pot,低水分条件下多耗0.98kg/pot),而耗水量/地下生物量的比值平凉40低于长武135,从而平凉40品种单位根量消耗的水分低于长武135。总之,在两个生长属性接近的冬小麦品种中,老品种以较大的根系生物量赢得了较高的竞争能力,消耗了较多的水分,而新品种虽然根系生物量较低,耗水量较少,但籽粒产量却较高。亦即,小麦新品种籽粒产量的提高是与根系的减少和对水资源竞争能力的下降相伴随的。     

羊草和紫花苜蓿人工草地光合特性

为探究单播与混播人工草地对羊草和紫花苜蓿光合特性的影响,测定2种牧草光合特性日变化进程,比较不同处理下羊草和紫花苜蓿光合特征。结果表明：单播处理下,羊草和紫花苜蓿的净光合速率、蒸腾速率、叶片温度呈单峰型,紫花苜蓿的气孔导度呈单峰型,羊草的气孔导度和水分利用效率呈双峰型。混播处理下,羊草和紫花苜蓿的净光合速率、蒸腾速率、叶片温度日变化呈单峰型,羊草的气孔导度和水分利用效率呈单峰型,紫花苜蓿的气孔导度呈双峰型。混播处理下,羊草净光合速率峰值显著高于单播,分别为17.72和13.65μmol CO₂·m^-2·s^-1。单播和混播处理下,羊草叶绿素含量均高于紫花苜蓿,羊草叶片氮含量均低于紫花苜蓿,且混播羊草叶片氮含量显著高于单播羊草,二者分别为27.60和22.55 g·kg^-1。不同种植方式下,羊草和紫花苜蓿的净光合速率与气孔导度、蒸腾速率呈显著正相关,与胞间CO₂浓度呈显著负相关,紫花苜蓿的净光合速率与叶片温度、水分利用效率呈显著正相关。混播处理有利于增加羊草叶片氮含量。试验结果为牧...     

旱农区春小麦根系生长冗余与碳平衡关系的研究

利用McCree(1986)测定整株植物碳平衡的方法,研究了半干旱区3个春小麦品种的籽实产量、根量、根冠比与碳平衡的关系。结果表明在开花期地方品种和尚头较之现代品种有更大的根量和根冠比。同一品种不同水分条件下根和茎叶CO2交换率(CER)波动幅度与水分条件正相关;在相同水分条件下不同品种间,品种和尚头波动幅度最大,品种定西-24次之,品种陇春-8139最小。从根和茎叶呼吸及日净碳获得量随水分供给条件的变化来看,品种和尚头和品种定西-24与品种陇春-8139相比在资源获取器官上存在着生长冗余,而且这种冗余也表现在生理代谢上,随水分条件的改善而增加。说明大根系品种在根系上存在着冗余,减少根系冗余可望成为半干旱区小麦高产育种的一条有效途径。     

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。     

The relationship between competitive ability and yield stability in an old and a modern winter wheat cultivar

This study was conducted to determine if there were differences in competitive ability and yield stability on the growth of an old landrace of winter wheat (Triticum aestivum), Pinglang 40 (PL40), and a modern cultivar, Changwu135, (CW135), which differed in time of cultivar release, height, shoot and root biomass. A second aim was to investigate whether there is a relationship between competitive ability and yield stability. One pot and two field experiments were conducted to monitor changes in the competitive ability and yield stability of an old and a modern winter wheat cultivar grown in monoculture and mixtures using a de Wit replacement series. The pot study was conducted at two soil moisture levels: (a) well watered (WW), soil maintained at 85% field capacity, and (b) moderate drought (MD), soil maintained at 55% field capacity. The field experiments were conducted in 2 years that were drier than the average. In the second field experiment 40 mm of irrigation was applied to half of the plots at jointing, booting and anthesis. The results were similar in the pot and field experiments. In the mixture, the old cultivar PL40 had a greater relative yield with a larger number of spikes per plant when compared with those of the modern cultivar CW135. The dry matter per stem of CW135 tended to decrease with the increasing proportion of PL40, indicating a lower competitive ability of the modern cultivar than that of the old cultivar. The superior competition of PL40 was primarily due to the higher plant height, larger leaf area index, greater tillering capacity and larger root system. Our results showed that the modern cultivar CW135 produced a higher grain yield, yield components (except spike number), water use efficiency (WUE_g) and harvest index under both water regimes in monoculture. However, the reduction in grain yield of CW135 when subjected to water-limited conditions was less than that of PL40 in the pot and field experiments. The greater grain yield of the CW135 was associated with a higher harvest index, thousand-kernel-weight and a lower root:shoot ratio. Water consumption over the entire growing period was significantly lower in CW135 under all soil moisture conditions, and the main difference in water consumption between the two cultivars was observed before anthesis. Post-anthesis accumulation of dry matter was greater in CW135 under water-limited conditions, but there was no difference between cultivars when water was adequate. The dry matter remobilization and contribution to grain yield of CW135 was lower than that of PL40. The results of the present study demonstrated that the higher competitive ability in the old landrace led to an increased sensitivity to environmentally-induced stress. As a result, there was a greater loss in grain yield by the old cultivar when the water supply was unfavorable. In addition, the differences in the life history strategy between the old and modern cultivars imply that reducing competitive ability in the modern cultivar has led to increased yield of the crop population and greater yield stability.     

Development of lucerne (Medicago sativa L.) treated with mineral fertilizer and manure at optimal and water deficit conditions

A study on the effect of different rates of mineral fertilizer and manure on yield parameters of lucerne under optimal and water deficit conditions was carried out. Leached chernozem soil and lucerne cultivar Victoria were used. The soil was treated with ammonium nitrate and fully matured cattle manure. The plants were grown under optimum moisture content of 80% and 40% of field capacity. The water deficit stress decreased top and root biomass by 11-75% and 3-29% at mineral and organic fertilization, respectively. The applied mineral and organic N strongly depressed nodules development. Both mineral fertilizer and organic manure at dose of 210 mg N kg(-1) soil completely inhibited the appearance of nodules. Next to nitrogen, water deficit stress further inhibited the development of nodules. Nitrogen fertilization increased seed productivity in the two experimental moisture conditions. The water deficit stress decreased seed productivity by 18 to 33% as compared to optimum conditions. The plant treatments with manure were much more resistant to water deficit and recovering ability of plants was faster as compared to treatments with mineral fertilizer. The application of manure stimulates development of drought-stress tolerance in lucerne. However, the results obtained can be considered for the soil type and experimental conditions used.     

Donald’s Ideotype and Growth Redundancy: A Pot Experimental Test Using an Old and a Modern Spring Wheat Cultivar

Human selection for high crop yield under water-limited conditions should have led modern cereal cultivars to invest less in root biomass, be it unconsciously. To test this hypothesis we conducted a pot experiment with two spring wheat cultivars, one old and one modern, both widely grown in the semi-arid regions of China. Using the replacement series method introduced by de Wit, we showed that the older landrace (Monkhead) was significantly more competitive than the more-modern cultivar (92-46). However, when grown in pure stand, old Monkhead had grown root biomass 3.5 times modern 92-46, whereas modern 92-46 gained a 20% higher grain yield. We also found modern 92-46 significantly increased root biomass per plant and root allocation (i.e., root biomass/total individual biomass) as its frequency in mixtures decreased, whereas old Monkhead did not respond in a similar way. This result suggests that the roots of modern cultivars may have gained an ability to recognize neighboring root systems and show more plastic self-restraining response to intra-cultivar competition.     

半干旱区春小麦不同年代品种根系生长冗余的比较实验研究

 研究了半干旱区几个春小麦品种的籽实产量、根量与根茎比的关系。表明在开花期地方品种和尚头较之现代品种有更大的根量和根茎比。产量因降水条件而不同：极端干旱的1995年,大根系品种与现代品种产量无显著差异(p>0.05);在降水分配较为均匀的1996年,无论有、无灌溉条件,具较大根系的地方品种与现代品种的产量均最低(p<0.05),而根量与品种产量及地上生物量呈显著的负相关。表明大根系品种在根系上存在着冗余,减少根系冗余可望成为半干旱区小麦高产育种的一条有效途径。     

Responses of photosynthetic rates and yield/quality of main crops to irrigation and manure application in the black soil area of Northeast China

Soil nutrients and water have long been recognized as the main determining factors influencing agricultural productivity in rain-fed agriculture. Manure application and irrigation can increase crop yield when nutrients and water are deficient. Often effects of water and nutrients are closely related and can not be easily separated in actual production. Three years of experiment were conducted in northern part of black soil area of Northeast China to investigate the responses of photosynthetic rates and yield/quality of main crops, wheat (Triticum aestivum L.), maize (May zeas L.), soybean (Glycine max L. Merr.) to irrigation and manure application. Irrigation and manure application had no effects on photosynthetic patterns during reproductive development in crops, maximum photosynthetic rates were achieved by irrigation, and manure application maintained relatively higher photosynthetic rates after the peak. On average, higher photosynthetic rates with irrigation may contribute to higher yield in soybean but not in maize and wheat. Responses of crop yield and quality to manure application and irrigation varied in the crops. Soybean yield and quality was very sensitive to irrigation and manure application. The greater supply of nutrients with sufficient water, the higher the yield. However, the high-yield of soybean achieved was accompanied with a decline of seed protein content. Maize yield mainly depended on nutrients used not the water supply, irrigation resulted in higher water content in the seed of maize and lower grain protein content in wheat at harvest, which is detrimental to seed storage in maize and processing quality in wheat. In the northern part of black soil area in Northeast China, the management of manure is critical to improve crop production, the optimum management for maize and wheat production was to apply chemical fertilizer and manure without irrigation, but for soybean was to apply fertilizer and manure with irrigation.     

水氮互作对小麦土壤水分利用和茎中果聚糖含量的影响

通过田间试验,以强筋小麦济麦20为材料,设置3个施氮水平：0 kg·hm^-2（N₀）、180 kg·hm^-2（N₁）、240 kg·hm^-2（N₂）;4个灌水处理：不灌水（W₀）、底墒水+拔节水+开花水（W₁）、底墒水+冬水+拔节水+开花水(W₂)、底墒水+冬水+拔节水+开花水+灌浆水(W₃),每次灌水量为60 mm,研究水氮互作对土壤水分含量、旗叶光合速率、倒二茎中果聚糖含量及氮肥和水分利用效率的影响.结果表明：施氮水平为180 kg·hm^-2处理的旗叶光合速率和倒二茎中果聚糖含量较高,籽粒产量、氮肥表观利用效率、氮肥农学利用率和水分利用效率最高;施氮水平为240 kg·hm^-2处理的茎中果聚糖含量较高;不施氮（N₀）或施氮过多（N₂）均不利于小麦籽粒产量、氮肥和水分利用效率的提高.W₁水分处理促进了倒二茎中果聚糖的积累和向籽粒的转运,有利于产量的提高.180 kg·hm^-2施氮水平配合灌溉底墒水+拔节水+开花水的水氮交互处理（N₁W₁）具有较高的籽粒产量及较高的氮肥和水分利用效率,在此基础上增加施氮量或灌水量,小麦旗叶光合速率和倒二茎中果聚糖含量升高,籽粒产量无显著变化或降低,氮肥和水分利用效率降低.     

Analysis of Phaseolus–Rhizobium interactions in a subsistence farming system

Poor bean yields in the Cunha region of the Mata Atlântica ecosystem in the state of São Paulo, Brazil, are associated with low agronomic inputs, plant disease, and soil erosion. To identify sustainable farming practices that increase production and maximize biological N2 fixation (BNF), the effects of soil fertility and plant cultivar on seed yield and root nodule formation were measured under standard agronomic practices. Results from 16 sites showed that fertilizing with lime and molybdenum increased seed yields to 370% for the landrace Serro Azul. In addition to increased yields, plants grown with fertilizer had more nodules. Marked strains of Rhizobium tropici were tested under controlled environments. An indicator strain of Rhizobium containing the gusA marker gene was used. Our results verify that the indicator strain CM-255 GusA+Hup+ had a high capacity to associate with the five bean varieties tested. Fertilization with P, K, S + micronutrients and liming were essential for better nodulation by the indicator strain. Under low fertility conditions, the landrace variety Serro Azul was poorly nodulated, when associated with native strains or with the indicator strain. However, under better soil fertility conditions, nodulation of Serro Azul by the marked Rhizobium strain was increased. The commercial variety Carioca 80SH showed no increase in nodulation (nodule number).