不同育秧方式和施肥水平下华南双季早稻秧苗生长特性的初步研究

本试验初步研究了华南双季早稻秧苗于不同育秧方式和施肥水平下的生长特点,结果表明:(1)旱育秧与湿润育秧秧苗在形态生长上的差异主要在于秧苗的叶片数不同,湿润育秧的出叶速度比旱育秧明显地快.(2)在有机质含量较高通气性能较优良的砂质壤土上进行旱育秧,基肥种类与施肥量在一定范围内时,具5片叶以下的旱育小苗的叶片数和株高无显著差异。(3)播后5天内的出苗率湿润育秧比旱育秧要显著地快而齐,而成秧率则各处理间有高有低,无明显规律可循,这与我们过去报道的结果趋势一致。(4)旱育秧移栽后的发根力比湿润秧要强,这种优势可维持到第9天才消失,再加上白/褐根的比例湿润秧要大,可能是导致旱育秧移栽后根系“爆发力”强、返青活棵快的重要因素。     

不同育秧方式和插植密度下华南双季晚籼稻根系活力的初步研究

本试验于1995年晚季初步研究了水、旱育秧方式和不同插植密度下根系活力的变化趋势及与地上部生长发育的关系。结果表明:(1)旱育秧苗根系活力明显高于水育秧,根系活力与白根数、地上部苗体干/鲜重比值呈显著正相关,与褐根数、苗高、叶龄和百苗干、鲜物重呈负相关。(2)旱育单苗移植处理的根系活力在水稻整个生育过程中均高于旱育多苗移植处理,水秧单苗和多苗移植处理。生育后期根系活力与主茎功能叶片叶绿素含量和叶面积系数分别呈极显著正相关和正相关,旱育秧苗的这些特性有利于移植后叶片与分蘖的快速形成及生育后期延缓叶片衰老,提高籽粒充实度。同时提出,在水肥管理上应适当加大后期穗肥比例,改善光照条件和土壤的通气排水状况,以便充分发挥旱育稀植秧苗的增产优势。     

水稻育秧技术与病虫害防治

水稻种植过程中育秧阶段非常关键,农谚道":秧好一半稻"。水稻育秧技术在不断提高,北方已经不用传统的水育秧了,湿润育秧和旱育秧在以前的基础上有很大变化。现在育秧方式有很多种,比如薄膜育秧、工厂化育秧,以及与机插相配套的秧盘育秧、干旱育秧等方式。     

遮阴对石笔木苗木生长和保护酶活性的影响

为探讨石笔木Tutcheria championi苗木对遮阴环境的适应性,以全光照(无遮阴覆盖)为对照,研究遮阴30%、50%和70%对2年生石笔木苗生长和生理特性的影响。结果表明,全光照下石笔木苗木生长较为健壮,其苗高、地径生长优于遮阴处理;全光照下石笔木总生物量、根生物量比以及根冠比显著大于遮阴处理(P<0.05);50%遮阴处理苗木叶片叶绿素含量显著高于全光照和70%遮阴处理(P<0.05),叶绿素a/b值在各处理间无显著差异。丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性在各处理间无显著差异(P>0.05);70%遮阴处理的苗木叶片过氧化氢酶(CAT)活性最高,显著高于全光照和50%遮阴。由此表明,充足的光照环境有利于石笔木苗木生长。     

广东南澳岛不同森林群落的林窗环境对移植树苗生长的影响

在广东南澳岛四个森林群落内移植了大叶相思（Acacia auriculaeformis),尾叶桉（Eucalyptus urophylla)和荷木（Schima superba)三种树苗,通过测定群落内林窗和非林窗生境中的叶面积指数,透光率和幼苗的生长高度,观察林窗环境对移植树苗生长的影响。结果表明：林窗的叶面积指数比非林窗的小;林窗的透光率大于非林窗;各群落的叶面积指数和爱光率有季节性的变化,变化幅度各不同,三种幼苗在林窗内比非林窗的乔木层下生长快;大叶相思和尾叶桉幼苗在林窗内的高度增长量显著大于非林窗下的,荷木虽也存在差异,但不如前两者显著。这些结果反映了不同生态特性的树种对林窗的反应不同。     

遮阴对地枫皮幼苗生长和生物量分配的影响

为了解光照强度对地枫皮(Illicium difengpi)幼苗生长和生物量分配的影响,对不同等级幼苗在不同遮阴处理下的形态和生物量变化进行了研究。结果表明,遮阴处理下幼苗的株高、冠宽和平均单叶面积均显著高于对照,同时比叶面积均随光强增大而显著降低。除I级苗50%遮阴处理外,全光处理下各等级幼苗的根长均显著高于遮阴处理。随着光照强度的增加,各等级幼苗的根生物量比与根冠比显著增加,叶生物量比显著减少;不同等级幼苗对强光和弱光环境均表现出较强的适应性,但以50%遮阴处理的总生物量最大,全光和85%遮阴处理均较小。遮阴处理的幼苗个体大小与其初始大小呈正相关,其中II级苗与I级苗差别较小,III级苗生长较差。在人工育苗条件下I级苗数量不到10%,较差的种苗质量叠加喀斯特山顶恶劣环境,可能是导致野外幼苗更新限制的重要原因。因此在野外回归和人工栽培过程中宜选用I、II级种苗,光强控制在透光率50%为宜。     

遮阴对夏玉米干物质积累及养分吸收的影响

以振杰2号(ZJ2)、登海605(DH605)和郑单958(ZD958)为试验材料,在大田条件下设置花粒期遮阴(S₁)、穗期遮阴(S₂)、全生育期遮阴(S₃)3个遮阴处理,以自然光照条件为对照(CK),研究了遮阴对夏玉米干物质积累和氮、磷、钾吸收的影响.结果表明: 遮阴后夏玉米籽粒产量和单株干物质积累量显著降低,降低程度与遮阴时期有关,表现为S₃>S₁>S₂,其中S₁、S₂和S₃籽粒产量平均降低61.6%、25.3%和92.8%,说明花粒期遮阴较花前遮阴对夏玉米干物质积累和籽粒产量影响更大,不同品种的变化趋势相同.夏玉米植株花前养分吸收量表现为钾>氮>磷,植株吸收总量表现为氮>钾>磷.遮阴后植株氮和磷积累量显著减少,由于遮阴后干物质较对照降低程度大于对氮、磷吸收的降低程度,各处理氮、磷相对含量有所升高;遮阴后各处理植株钾吸收量较对照显著降低,但S₂处理的钾吸收降低程度大于干物质积累降低程度,钾相对含量降低,即花前遮阴对玉米钾吸收的影响大于氮和磷.     

杉木幼苗非结构性碳水化合物对遮阴及恢复光照的响应

该研究以盆栽杉木(Cunninghamia lanceolata)幼苗为研究对象,采用遮光率为60%的遮光网进行遮阴处理,以正常光照为对照,遮阴处理30 d后部分杉木幼苗进行20 d的光照恢复处理,测定分析遮阴及恢复光照处理后不同组织/器官的非结构性碳水化合物(NSC)浓度及其分配、以及NSC库的变化,以探讨杉木幼苗在遮阴及恢复光照后的NSC调控机制。结果显示:(1)遮阴能够显著降低杉木幼苗各组织/器官可溶性糖浓度,各组织/器官下降幅度依次为细根(71%)>当年生叶(68%)>一年生叶(58%)>树皮(57%)>木质部(55%)>粗根(45%);遮阴使淀粉浓度的下降程度显著高于可溶性糖,在所有组织/器官中粗根的淀粉浓度下降幅度最低(50%),其次是木质部(72%)细根的淀粉浓度下降最大。(2)遮阴处理使杉木幼苗各组织/器官的NSC浓度下降量均超过50%,但杉木幼苗的存活率依然为100%;遮阴后杉木幼苗的生物量变化无明显差异,但NSC库变小,NSC相对分配改变;遮阴后不同组织/器官的NSC下降程度不一,其中粗根的NSC浓度显著高于细根。(3)恢复光照处理后杉木幼苗各组织/器官的NSC浓度均可恢复到对照水平。研究证明,遮阴环境下杉木幼苗能够主动调节其NSC在各组织/器官的分配使其维持在一定范围,从而提高杉木幼苗对遮阴环境的适应性,而不是以牺牲生长为代价。     

广东南澳岛不同森林群落的林窗环境对3种移植树苗生长的影响

 先锋种和非先锋种可能对林窗产生不同的反应。在广东南澳岛4个不同的森林群落样地里移植了大叶相思（Acacia auriculaeformis A. Cunn.）、尾叶桉（Eucalyptus urophylla S. T. Blake）和荷木（Schima superba Gardn. et Champ）3种树苗,其中大叶相思和尾叶桉是先锋种,而荷木是非先锋种,测定了林窗和非林窗生境中的透光率和幼苗生长高度。结果表明,林窗的透光率大于非林窗的;各群落的透光率有季节性的变化,变化幅度各不同。3种幼苗在林窗内比     

光强梯度对羊草无性系分化与生长的影响

在温室内用透光率分别为 60 %、45%、30 %的遮阴网盖在花盆上遮阴 ,研究不同光照强度对羊草无性系分化与生长的影响 .结果表明 ,低光强影响羊草基株的生物量积累 ,抑制羊草无性系的分化和生长 .减少羊草地下根茎的数目 ( A=61 4个 ,D=2 31个 )和无性系分株数 ( A=70 4个 ,D=1 52个 ) .羊草根茎长度和节数、无性系分株干重等性状在不同的光强梯度之间存在显著差异 ( P<0 .0 1 ) ,这种差别在春季尤其显著 .     

玉米和大豆条带间作模式下的光环境特性

于2006—2007年对玉米/大豆窄条带间作系统的光环境特性进行观测,研究间作冠层内光合有效辐射（PAR）的空间分布,并分析光环境改变对作物产量的影响.结果表明：在生育早期,大豆条带边行（与玉米相邻行）底部光的透射率高于大豆内行,而玉米条带内行底部光的透射率高于边行;进入生殖生长后,冠层底部光的透射率变化不明显,平均透射率小于7%.在生育早期,内行大豆接收到的日平均光量子通量密度（PPFD）比边行高约10%;1∶3间作模式（I₁处理）下,大豆边行和内行光的透射率均比2∶3间作模式（I₂处理）高15%,表明I₂处理的玉米条带对大豆的遮荫程度大于I₁处理.在大豆开花之后,内行大豆接收到的日平均PPFD与两侧边行有显著差异,但边行之间差异不显著;内行和外行大豆光的透射率分别为38%和27%,但I₁和I₂处理之间差异不显著,表明两种间作模式下玉米条带对大豆的遮荫程度相近.大豆内行的生物量高于边行,而边行之间没有显著差异,表明在充分供水条件下,不同窄条带间作模式对作物生物量的影响主要是由于作物光环境的改变所致.     

水稻冠层光合有效辐射的时空分布特征

以2个不同株型水稻品种为材料,设置高、中、低3个施氮水平,利用SunScan冠层分析仪于灌浆期系统测定了不同施氮水平下不同株型水稻品种植株形态和冠层内光合有效辐射（PAR）的时空分布状况.结果表明：施氮量对水稻株高、穗弯曲度和茎叶夹角有明显影响;群体叶面积的垂直分布呈中部>上部>下部的分布特征,最大分层叶面积指数（LAI）出现在0.60相对高度处.冠层内平均PAR透光率从顶部向下递减,且在冠层上中部递减迅速,下部递减缓慢;平均PAR透光率随施氮量的增加而递减;平均PAR透光率日变化表现为早晚较低,中午较高;平均PAR透光率随向下累积LAI的增加呈指数递减,群体消光系数K的日变化表现为早晚较高,中午较低,灌浆期的K值介于0.35～0.50.水稻冠层内PAR的三维空间分布表现为冠层上中部水平面上PAR透光率高,光斑面积大;下部水平面上PAR透光率低,光斑少;同一冠层高度水平面上的PAR光强呈不均匀分布.株型紧凑的水稻品种,冠层透光率高,透光率日变化大,群体消光系数小.     

弱光胁迫对不同基因型玉米生长发育和产量的影响

以不同基因型玉米为材料,在玉米生长发育的3个主要阶段(苗期、穗期、粒期)进行分期遮光试验,研究不同时期弱光胁迫对不同基因型玉米生长发育和产量的影响。结果表明,遮光延缓了玉米叶片的出生速度,使叶片变薄;遮光可以延缓叶片的衰老,但遮光解除后则加速叶片的衰老;遮光造成植株高度增加,但恢复正常光照后,其株高却逐渐低于对照;遮光使干物质积累下降,抽雄吐丝日期推迟,尤其是吐丝日期推迟更多,并使产量降低,但不同基因型玉米不同遮光处理下降程度不同。试验的4个品种中,掖单2 2和豫玉2号受遮光影响较小,而掖单36 38和丹玉13受影响较大,即不同基因型玉米对弱光胁迫的敏感性不同     

How tree species identity and diversity affect light transmittance to the understory in mature temperate forests

Light is a key resource for plant growth and is of particular importance in forest ecosystems, because of the strong vertical structure leading to successive light interception from canopy to forest floor. Tree species differ in the quantity and heterogeneity of light they transmit. We expect decreases in both the quantity and spatial heterogeneity of light transmittance in mixed stands relative to monocultures, due to complementarity effects and niche filling. We tested the degree to which tree species identity and diversity affected, via differences in tree and shrub cover, the spatiotemporal variation in light availability before, during, and after leaf expansion. Plots with different combinations of three tree species with contrasting light transmittance were selected to obtain a diversity gradient from monocultures to three species mixtures. Light transmittance to the forest floor was measured with hemispherical photography. Increased tree diversity led to increased canopy packing and decreased spatial light heterogeneity at the forest floor in all of the time periods. During leaf expansion, light transmittance did differ between the different tree species and timing of leaf expansion might thus be an important source of variation in light regimes for understory plant species. Although light transmittance at the canopy level after leaf expansion was not measured directly, it most likely differed between tree species and decreased in mixtures due to canopy packing. A complementary shrub layer led, however, to similar light levels at the forest floor in all species combinations in our plots. Synthesis. We find that a complementary shrub layer exploits the higher light availability in particular tree species combinations. Resources at the forest floor are thus ultimately determined by the combined effect of the tree and shrub layer. Mixing species led to less heterogeneity in the amount of light, reducing abiotic niche variability.     

Effect of arbuscular mycorrhizal fungi inoculation of rice seedlings at the nursery stage upon performance in the paddy field and greenhouse

We examined the effect of arbuscular mycorrhizal fungi inoculation at the nursery stage on the growth and nutrient acquisition of wetland rice (t Oryza sativa L.) under field and pot conditions. Seedlings were grown on -ray sterilized paddy soil in two types of nurseries, namely dry nursery and wet nursery, with or without arbuscular mycorrhizal fungi (AMF) inoculation which was a mixture of indigenous AMF (t Glomus spp.) spores collected from the paddy field. Five-to-six week old seedlings were transplanted to the unsterilized soil under field and pot, respectively. Mycorrhizal seedlings had higher shoot biomass under both nursery conditions 5 weeks after sowing. Mycorrhizal colonization and sporulation were 2 to 3 times higher in the dry nursery than the wet nursery at the transplanting stage. Mycorrhizal colonization of plants inoculated in the nursery remained higher than those not inoculated under both field and pot conditions. Sporulation after transplanting to field conditions was about 10 times higher than in the pot. Inoculated plants produced higher biomass at maturity under field conditions, and the grain yield was 14-21% higher than those not inoculated. Conversely, grain yield and shoot biomass were not significantly influenced by AMF colonization under pot conditions. For plants originating from the dry nursery, N, P, Zn and Cu concentrations of field-grown plants at harvest were significantly increased by preinoculation with AMF over those left uninoculated. We conclude that the AMF inoculation at the nursery stage under both dry and wet conditions increased growth, grain yield and nutrient acquisition of wetland rice under field conditions.     

遮荫处理对梅叶冬青叶片形态、光合特性和生长的影响

为了解遮荫环境对梅叶冬青(Ilex asprella)生长和光合特性的影响,采用遮荫网的方法模拟85%、56%和全光照等3种光照环境,研究了遮荫对其生长、光合参数以及生物量等的影响。结果表明,经一年遮荫处理后,梅叶冬青的叶绿素a、b和叶绿素总量都随着遮荫强度的增加而显著增高,胡萝卜素含量则显著降低。与对照相比,56%遮荫处理显著提高梅叶冬青的最大净光合速率和光饱和点,分别提高了17.6%和25.2%,但是85%遮阴处理则显著降低最大净光合速率和光饱和点,分别降低了18.2%和24.1%,两种遮荫处理均显著降低了光补偿点。叶长、叶宽、比叶面积、单片叶面积和叶片含水量均随着遮荫强度的增加而显著增加,而叶片厚度则显著减小。遮荫处理明显抑制整株生物量增长,减小根冠比,但是株高、冠幅和径向生长随遮荫处理时间不同而有所变异。因此,梅叶冬青有耐荫偏阳的特性,在林下种植时需及时调控乔冠层的透光率,一般应大于44%。     

New options for land rehabilitation and landscape ecology in Southeast Asia by “rainforestation farming”

Continental and insular Southeast Asia were originally endowed with vast areas of luxurious Tropical Evergreen Forest. Mainly since the sixties of the last century these tropical rainforests have been under a steadily increasing pressure due to intensive logging for commercial purposes and the increasing number of people depending on the given environment for more agricultural land and for fuel wood.One innovative approach to combine the necessities of rural development, safe natural resource management and biodiversity restoration was developed under the acronym “Rainforestation Farming” on the island of Leyte in the Philippines. More than 100 different local forests and fruit tree species were tested and planted in a near-to-nature planting scheme concerning species composition in a former degraded area covered by Imperata cylindrica.The recommended planting scheme includes both sun-requiring trees and shade-loving trees, highly valuable timber trees and fruit trees. During the first year of planting, nursery grown sun-loving trees were planted at close distance of 2×2 m to quickly reach the condition of a closed canopy and therefore shading out of the grass. During the second year, shade-loving trees, coming from either the nursery or from the natural forest in the form of seedlings sitting under mother trees, were planted under the established first year pioneers.To support the protection of the remaining forest, particularly the mother trees as resource for seedlings and to spur biodiversity rehabilitation efforts through people's participation a support system with community organisers was established. Already after four years some highly endangered species like the herbivorous Flying Lemure, Gynocephalus volans, and the insectivorous nocturnal ape, Tarsius syrichta, moved back into parts of the reforested closed canopy areas of the research and model farm.     

太阳辐射对稻田甲烷排放的影响

太阳辐射减弱是气候变化的主要特征之一,而太阳辐射减弱对稻田甲烷(CH4)排放的影响尚不明确,且缺少高光谱遥感用于估算稻田CH4排放的研究.通过田间模拟试验,研究了不同遮阴强度对稻田CH4排放和水稻冠层光谱特征的影响,并基于冠层高光谱数据估算了CH4排放通量.采用单因子试验设计,遮阴强度设3个水平,即对照(不遮阴,CK)、轻度遮阴(S1,单层遮阴,遮阴率为60%)和重度遮阴(S2,双层遮阴,遮阴率为84%).结果表明:与对照相比,遮阴明显降低了稻田CH4排放,但重度遮阴下CH4排放高于轻度遮阴;近红外波段水稻冠层反射率表现为CK>S2>S1;水稻冠层光谱反射率(699~1349 nm)与CH4排放通量呈极显著正相关,最高相关系数达0.64,6种植被指数与CH4排放通量也呈极显著相关,其中比值植被指数(RVI)与CH4排放通量的相关系数最大,达0.84;建立了以RVI、归一化植被指数(NDVI)和507 nm原始反射率(ρ507)为参数估算CH4排放通量的逐步回归模型,决定系数R2分别为0.86和0.85,利用该模型可为开展区域稻田温室气体排放的遥感监测提供试验依据.     

Decoupling of light intensity effects on the growth and development of C3 and C4 weed species through sucrose supplementation

Light availability has a profound effect on plant growth and development. One of the ways to study the effects of light intensity on plant growth and development without the confounding problem of photosynthate availability is sucrose injection/supplementation. A greenhouse experiment was conducted to evaluate the effects of light levels (0% and 75% shade) and sucrose injection (distilled water or 150 g sucrose l(-1)) on three weed species: redroot pigweed (Amaranthus retroflexus L., C4), lambsquarters (Chenopodium album L., C3) and velvetleaf (Abutilon theophrasti Medic., C3). The average total sucrose uptake was 7.6 and 5.9 g per plant for 0% and 75% shading, respectively, representing 47% of the average total weed dry weight. Plants injected with sucrose had greater dry weights and shoot-to-root ratios under both light levels. In spite of sucrose supplementation the reduction in dry matter due to shading was greater for roots and reproductive structures than vegetative shoot tissues, indicating light level regulation of morphological changes resulting in changed C allocation that are independent of photosynthate availability. Dry weights of plants injected with sucrose under 75% shading were not different from distilled water-injected unshaded plants. However, both sucrose-injected and control plants, regardless of their photosynthetic pathways, underwent similar changes in allocation of dry matter and morphology due to shading, suggesting that these effects are strictly due to light intensity and not related to photosynthate availability.