水肥条件对新老两个春小麦品种竞争能力和产量关系的影响

采用de Wit替代系列实验研究了传统地方品种和尚头和现代品种定西-24在土壤水肥梯度下混播时的竞争结局以及竞争能力和单播产量之间的关系。在各个水肥处理条件下,混播时,虽然和尚头对定西-24的影响效应有所减弱,但是,和尚头对定西-24的竞争结局并没有发生改变:和尚头最终完全排除定西-24,成为竞争中的优胜者。在低水无肥和高水高肥条件下,定西-24的单播产量显著高于和尚头的单播产量,二者的竞争能力与其单播产量之间呈负相关;在低水低肥条件下,和尚头的单播产量与定西-24的单播产量几乎相等,二者的竞争能力与其单播产量之间没有特定的关系;在中水中肥条件下,和尚头的单播产量高于定西-24的单播产量,二者的竞争能力与其单播产量之间呈正相关,据此可以认为和尚头和定西-24混播时的竞争能力与其单播产量之间没有特定的关系。在低水无肥和高水高肥条件下,定西-24的单播地上生物量显著高于和尚头的单播地上生物量。在水分严重亏缺的条件下,和尚头的水分利用效率显著低于定西-24的水分利用效率;随着水分供给的改变,和尚头的水分利用效率得到了显著提高,然而当水分不再成为和尚头生长限制因子时,其水分利用效率降低,结果表明一定程度水分利用效率的提高有利于春小麦适应半干旱区的水分环境。     

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。     

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。     

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。     

不同密度混播对玉米植株13C同化物分配和产量的影响

为了探讨不同密度混播对玉米植株¹³C同化物分配和产量的影响,选用‘郑单958’(ZD)和‘登海605’(DH)为试验材料,在不同密度下(LD,67500株·hm^-2;HD,97500株·hm^-2)设置单播(SZD、SDH)与混播(M、1∶1、2∶2)处理,研究玉米品种不同密度混播对植株光合特性、¹³C同化物分配、干物质积累量和产量的影响.结果表明: 随密度增加,籽粒产量、¹³C同化物在籽粒中的分配、干物质积累量和叶面积指数均提高;而叶绿素含量和净光合速率则降低.在67500株·hm^-2下,混播较单播处理无显著优势,但在97500株·hm^-2下,两品种混播提高了叶面积指数、叶绿素含量和穂位叶净光合速率,干物质积累量增加.混播促进茎等营养器官的干物质向籽粒的转运,提高了¹³C同化物在籽粒中的分配比例.混播处理较单播产量增加,主要因为千粒重显著增加.在高密度种植条件下,混播有助于扩大光合面积,维持较高的净光合速率,提高群体干物质积累量,改善干物质的分配状况,增加同化物向籽粒的分配,最终提高夏玉米产量.可见,混播栽培可显著增加黄淮海区密植夏玉米产量.     

不同密度混播对玉米植株13C同化物分配和产量的影响

为了探讨不同密度混播对玉米植株¹³C同化物分配和产量的影响,选用‘郑单958’(ZD)和‘登海605’(DH)为试验材料,在不同密度下(LD,67500株·hm^-2;HD,97500株·hm^-2)设置单播(SZD、SDH)与混播(M、1∶1、2∶2)处理,研究玉米品种不同密度混播对植株光合特性、¹³C同化物分配、干物质积累量和产量的影响.结果表明: 随密度增加,籽粒产量、¹³C同化物在籽粒中的分配、干物质积累量和叶面积指数均提高;而叶绿素含量和净光合速率则降低.在67500株·hm^-2下,混播较单播处理无显著优势,但在97500株·hm^-2下,两品种混播提高了叶面积指数、叶绿素含量和穂位叶净光合速率,干物质积累量增加.混播促进茎等营养器官的干物质向籽粒的转运,提高了¹³C同化物在籽粒中的分配比例.混播处理较单播产量增加,主要因为千粒重显著增加.在高密度种植条件下,混播有助于扩大光合面积,维持较高的净光合速率,提高群体干物质积累量,改善干物质的分配状况,增加同化物向籽粒的分配,最终提高夏玉米产量.可见,混播栽培可显著增加黄淮海区密植夏玉米产量.     

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.     

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。     

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。     

高寒山区混播草地燕麦和毛苕子种间竞争对密度的响应

混播草地种内与种间竞争的强弱和转化受混播牧草相对密度的制约。2010年6-9月采用取代系列实验方法,在石羊河上游建立燕麦(Avena sativa)和毛苕子(Vicia villo-sa)混播草地,按燕麦与毛苕子相对密度设置1∶0(KY)、8∶2(A)、6∶4(B)、5∶5(C)、4∶6(D)、2∶8(E)和0∶1(KM)7个处理,研究了密度制约下混播草地一年生牧草种间竞争的变化。结果表明:混播草地在密度影响下各物候期的种内与种间竞争发生不同程度的转化,所有混播处理中燕麦相对产量(RYy)随牧草的生长逐渐增加;混播处理A、B和C中毛苕子相对产量(RYm)随牧草的生长逐渐减小,混播处理D和E中逐渐增加;在燕麦出苗期和分蘖期除混播处理A外其余混播处理中两牧草为敌对关系(RYT<1),在牧草生长后期所有混播处理中两牧草转化为共生关系(RYT!1),且燕麦的竞争能力强于毛苕子(RCCy!1、RCCm"1);所有混播处理在牧草整个生长阶段的竞争偏利于燕麦(AG<1)。混播草地内种间竞争在各物候期表现出明显的密度制约现象,实现了资源协同利用目标。     

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.     

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.     

断根对冬小麦竞争能力与产量的影响

 采用简化的deWit替代系列法研究了盆栽冬小麦‘长武135’（Triticum aestivum cv. Changwu 135）在拔节初期断根对冬小麦根冠关系、竞争能力及其与产量性状的关系。无论干旱或湿润，单栽条件下断根降低了小麦的根冠比，在混栽条件下，断根小麦的相对穗重和相对地上部生物量均显著低于未断根小麦，说明断根降低了小麦的竞争能力。根冠比越大竞争能力越强，即作物的竞争能力与根冠比存在正相关关系。单栽湿润条件,断根降低了小麦的穗重和籽粒产量，而在中等干旱条件下，断根小麦穗重和籽粒产量高于未断根小麦 。说明在水资源充分的条件下，较高的作物个体竞争能力则具有较高的生产能力，而在水资源有限的情况下，降低作物个体竞争能力反而提高了群体籽粒产量。     

Competition and sensitivity of wheat and wild oat exposed to enhanced UV-B radiation at different densities under field conditions

The influence of enhanced UV-B radiation (approximating a 15% ozone layer reduction) on competitive interaction between spring wheat (Triticum aestivum) and wild oat (Avena fatua) was examined in the field. The density-dependent mortality of both wheat and wild oat did not exhibit a significant difference between control and UV-B treatment conditions. A relatively high degree of competitive stress enhanced the effects of UV-B stress on biomass reduction. The relative competitive status of wheat in terms of total biomass increased under UV-B enhancement while it decreased when based upon grain production. Shifts in competitive balance occurred with significant changes in total biomass, especially when plants grew at higher densities in monocultures and mixtures. The sensitivity of wild oat to intensification of UV-B radiation at higher densities in mixtures was greater than that at lower densities. At all densities examined, wheat grown in mixture was significantly less sensitive to UV-B radiation than that in monoculture, and just the opposite for wild oat. The density of monocultures did not alter the response index (RI) of wheat and wild oat to enhanced UV-B radiation.     

暖冬条件下播期对不同类型小麦幼穗分化的影响

对3个不同类型小麦品种在不同播期下的幼穗分化进程及受冻情况进行了系统观察和研究。结果表明,在气候变暖,秋、冬温度较高的情况下,小麦幼穗分化进入各时期的时间早晚为强春性品种>春性品种>半冬性品种;播期对小麦幼穗分化的伸长期、单棱期和二棱期持续时间长短影响较大;在早播的情况下。春性越强的小麦品种,越冬前幼穗分化发育速度越快,达到的发育阶段越高,越冬期间越容易被冻死。据此,提出在河南气候变暖,秋、冬温度较高的情况下,首先在生产上要选用半冬性品种,适当搭配晚播早熟的春性品种;其次,无论半冬性品种或春性品种。播种期都不宜过早。