不同种植密度下玉米与豌豆间作对群体总产量的影响

于2014和2015年在黄土高原半干旱区全膜覆盖种植技术下,研究了不同种植密度下玉米行内间作豌豆对作物群体总产量的影响.结果表明: 2014年,当玉米株距为40和50 cm时,与不插播相比,在玉米株间插播2株豌豆显著提高了作物群体籽粒总产量;而在株距60 cm情况下,插播豌豆对作物群体总产量无显著影响.2015年,玉米株距40和50 cm情况下,与对应株距的单作玉米相比,在玉米株间插播2株豌豆对群体籽粒总产量无显著影响;但是在玉米株距60 cm的情况下,株间插播2株豌豆使作物群体籽粒总产量显著增加.导致两个试验年份之间玉米行内间作豌豆的产量效应差异的主要原因是生长季降水量在2014年较2015年充沛.综合比较,玉米株距40 cm、株间插播2株豌豆间作形式的籽粒总产量最高.此外,在玉米单作和行内间作中,籽粒总产量均随玉米株距的增大而减小.     

植被界面过程(VIP)模型的改进与验证

为了提高植被界面过程(VIP)模型的预报能力,对VIP模型的一些参数化方案进行了更新,包括基于相对生育期的根深动态、根系分布密度和比叶面积季节变化,使模型能从机理上更合理地描述作物同化物分配及土壤水分运动。将改进后的模型应用于河北栾城冬小麦生长季的叶面积指数、生物量和土壤水分模拟,并与相应时期的试验资料对比验证。结果表明,改进后的VIP模型对土壤水分动态和冬小麦叶面积指数的模拟效果更好,模型各状态变量模拟值与观测值的均方根误差和相关系数都得到明显提高。     

夏玉米叶片含水率及光合特性对不同强度持续干旱的响应

基于七叶期开始的夏玉米全生育期不同强度的干旱发生发展模拟试验资料,分析了不同强度的干旱发生发展对夏玉米叶片含水率及光合特性的影响。结果表明:夏玉米生育期内叶片含水率随干旱发生发展呈线性下降趋势,并与土壤相对湿度通过0.005水平的显著性检验,可表征玉米的受旱程度。玉米全生育期内叶片的光合速率、蒸腾速率和气孔导度均随干旱的发生发展呈显著下降趋势,且不同强度干旱的影响差异随时间推移而减小;而叶片水分利用效率则随干旱发生发展呈升高趋势,且随着干旱的发展不同强度干旱间的差异呈增加趋势。玉米全生育期内均出现了光合作用由气孔限制向非气孔限制的转换,转换时间分别为46、38、30和35 d,与干旱强度及持续时间呈反比。     

高光谱植被指数与水稻叶面积指数的定量关系

基于不同水稻品种、施氮水平和不同生育期下的大田试验,确立了水稻叶面积指数（LAI）与冠层光谱特征参数的定量关系.结果表明：水稻叶面积指数与部分高光谱植被指数存在良好的相关性,其中原始光谱组成的2波段差值指数（DI）形式相关性最好,其次为比值（RI）和归一化（NI）植被指数.相关最好的原始光谱植被指数是由近红外波段组成的差值指数DI(854,760),相关最好的一阶导数光谱植被指数是红光和近红外光组成的导数差值指数DI(D₆₇₆, D₇₇₈),但总体上导数光谱指数不如原始光谱指数与LAI关系密切.独立试验数据检验结果表明,以差值指数DI(854,760)为变量建立的水稻LAI监测模型具有较好的表现,可用于水稻LAI的估测.     

Partitioning of dry mass and leaf area within plants of three species grown at elevated CO2

1. We tested the hypothesis that the net partitioning of dry mass and dry mass:area relationships is unaltered when plants are grown at elevated atmospheric CO₂ concentrations.
2. The total dry mass of Dactylis glomerata, Bellis perennis and Trifolium repens was higher for plants in 700 compared to 350 μmol CO₂ mol^–1 when grown hydroponically in controlled-environment cabinets.
3. Shoot:root ratios were higher and leaf area ratios and specific leaf areas lower in all species grown at elevated CO₂. Leaf mass ratio was higher in plants of B. perennis and D. glomerata grown at elevated CO₂.
4. Whilst these data suggest that CO₂ alters the net partitioning of dry mass and dry mass:leaf area relationships, allometric comparisons of the components of dry mass and leaf area suggest at most a small effect of CO₂. CO₂ changed only two of a total of 12 allometric coefficients we calculated for the three species: ν relating shoot to root dry mass was higher in D. glomerata , whilst ν relating leaf area to total dry mass was lower in T. repens .
5. CO₂ alone has very little effect on partitioning when the size of the plant is taken into account.     

Comparison of CO<Subscript>2</Subscript> and H<Subscript>2</Subscript>O fluxes over grassland vegetations measured by the eddy-covariance technique and by open system chamber

Measurements of CO₂ and H₂O fluxes were carried out using two different techniques—eddy-covariance (EC) and open system gas exchange chamber (OC)—during two-years’ period (2003–2004) at three different grassland sites. OC measurements were made during fourteen measurement campaigns. We found good agreement between the OC and EC CO₂ flux values (n = 63, r ² = 0.5323, OC F_CO2 = −0.6408+0.9508 EC F_CO2). The OC F_H2O values were consistently lower than those measured by the EC technique, probably caused by the air stream difference inside and outside the chamber. Adjusting flow rate within the chamber to the natural conditions would be necessary in future OC measurements. In comparison with EC, the OC proved to be a good tool for gas exchange measurements in grassland ecosystems.     

阴雨寡照地区高产水稻的生物学特征研究

以水稻(Oryza sativa Linn.)的常规稻品种‘黄华占’、‘湘早籼45’和‘湘晚籼13’,一般杂交稻品种‘金优402’和‘Ⅱ优838’,超级杂交稻品种‘株两优819’、‘丰源优299’、‘陆两优966’和‘Y两优1号’为实验材料,在2008年和2009年不同产季,对种植于多阴雨的湖南桃源县的不同品种水稻的产量构成因子、群体性状和叶片净光合速率(Pn)差异进行了研究.结果显示:在产量构成因子方面,不同品种水稻的有效穗数、每穗粒数、结实率、千粒质量和产量均有一定差异,超级杂交稻品种的产量高于一般杂交稻及常规稻品种;其中,产量分别与有效穗数和结实率呈显著正相关(P＜0.05),与每穗粒数呈极显著正相关(P＜0.O1),与千粒质量无显著相关性.在群体性状方面,不同品种水稻的株高、最大茎蘖数、最大叶面积指数(LAI)、生物量及收获指数均有一定差异,但产量分别与株高、最大LAI和生物量呈极显著正相关,与收获指数呈显著正相关,与最大茎蘖数无显著相关性;其中,产量与最大LAI的相关系数最大(0.889).在拔节期和抽穗期,各品种水稻单叶的Pn日变化曲线呈“双峰型”,Pn第1个峰值差异均较小,“午休”阶段以及第2个峰值Pn差异增大,总体上看“午休”阶段常规稻品种的Pn降幅明显大于杂交稻;各品种的Pn日平均值也有明显差异,常规稻品种的Pn日平均值总体上低于杂交稻.研究结果表明:在阴雨寡照的生态条件下超级杂交稻品种的产量高于其他类型水稻品种,其高产机制与叶面积指数的增加有关.     

多效唑在蔓性千斤拔上应用的初步研究

为了解生长调节剂提高蔓性千斤拔产量的方法及机理,进行多效唑对蔓性千斤拔的化控试验。在蔓性千斤拔初花期,设30、60和90株·m~(-2)3个植株密度,用浓度为0、300、600、900 mg·L~(-1)的多效唑对蔓性千斤拔进行叶面喷施,测定叶绿素、叶面积、叶面积指数及药材产量。结果表明,植株密度为60株·m~(-2)、多效唑喷施浓度为600 mg·L~(-1)的处理,蔓性千斤拔叶绿素含量显著高于其它处理,叶面积和叶面积指数适度缩小,药材干重提高了16.7%。初步确定蔓性千斤拔增产效果最好的植株密度为60株·m~(-2)、多效唑喷施浓度为600 mg·L~(-1)。     

稻鸭共生系统中鸭品种对水稻生长特性的影响

鸭子品种间的差异对稻鸭共生系统中水稻的生长特性可能有重要影响.为了探究鸭子品种对水稻生长特性的影响,选取水鸭(SY)、洋鸭(YY)和绿头鸭(LTY)3个常见鸭品种作为处理,以水稻常规单作(CK)为对照,采用随机区组设计的方法进行田间小区试验,研究其对水稻根部、茎部、叶部性状及水稻产量的影响.结果 表明:YY和LTY处理...     

獐茅种群地上生物量及光合面积等的生长季动态

獐茅(Aeluropus littoralis var.sinensis)是渤海湾和黄海等滩涂盐生草甸的建群种之一(吴征镒等,1980)。以獐茅为优势种的草地是一种重要的农牧业资源。对獐茅种群生物量及光合面积的研究,理论上有助于阐明该种群生长发育的基本规律;实践上对于指导农牧业生产以及合理利用这一自然资源也具有参考价值。     

小兴安岭三种林型叶面积指数的估测

利用Winscanopy2006冠层分析仪测定2009年7月初至11月初小兴安岭白桦次生林、谷地云冷杉林、阔叶红松林的有效叶面积指数(LAIe),并将经过木质部分所占比率、冠层水平集聚和簇内集聚校正的11月初LAIe作为真实叶面积指数(LAIt),结合凋落物法测定3种林型的LAIt及其季节动态.结果表明:调查期间,白桦次生林的LAIe在7月达到峰值(2.21),谷地云冷杉林、阔叶红松林的LAIe在8月达到峰值,分别为2.57、2.68.白桦次生林、谷地云冷杉林、阔叶红松林的LAIt均在7月达到峰值,分别为3.44、3.86、6.93;相对于本文探讨的方法,光学仪器所测定的LAIe在最高叶面积指数期分别低估33.1％、32.9％、66.0％;而在整个调查期内,谷地云冷杉林和阔叶红松林LAIe平均低估22.8％和56.5％,白桦次生林平均高估13.2％.     

Morpho-Physiological Aspects of Productivity and Quality in Squash and Pumpkins (Cucurbita spp.)

Squash and pumpkins are important horticultural crops worldwide, but there has been relatively little research to systematically describe yield components and improve productivity in this species. This review outlines some of the basic growth-analysis techniques for describing different aspects of productivity and attempts to summarize investigations on physiological, morphological, and ecological aspects of productivity and the relationship of these factors to eating quality in the three most important domesticated species of Cucurbita—C. pepo, C. maxima, and C. moschata. The emphasis of this review is on components of yield that can be modified either by selective breeding or through use of cultural techniques. Increasing economic crop yield while also balancing the needs to maintain and improve culinary qualities of the edible product will also be discussed. The bush phenotype is being increasingly exploited in new cultivar development. Advantages and disadvantages of using bush genotypes in cultivar development are addressed. In addition, because of increasing use of Cucurbita seeds for vegetable oils, snackseeds, and pharmaceutical purposes, physiological components of seed yield are also discussed.     

Physiological basis of differential response to salinity in rice cultivars

Growth analyses of rice Oryza sativa L. seedlings in salinized nutrient solution condition were conducted with 24 cultivars and lines after genetic purification. Cultivar differences in relative growth rate in salinized conditions were chiefly dependent on differences in shoot Na content. The shoot Na content was affected by Na selectivity in the root and by the leaf area ratio (LAR, leaf area per total dry weight). The contribution of LAR was equally important to that of root cultivar selectivity against Na uptake under a higher salinization condition where root selectivity against Na may be decreased due to reduced root activity. Cultivar differences in salt tolerance in highly salinized conditions were mainly attributed to differences in these two factors. A more convenient and efficient screening method for salt tolerance is proposed.     

小兴安岭三种林型叶面积指数的估测

利用Winscanopy2006冠层分析仪测定2009年7月初至11月初小兴安岭白桦次生林、谷地云冷杉林、阔叶红松林的有效叶面积指数(LAI_e),并将经过木质部分所占比率、冠层水平集聚和簇内集聚校正的11月初LAI_e作为真实叶面积指数(LAI_t),结合凋落物法测定3种林型的LAI_t及其季节动态.结果表明： 调查期间,白桦次生林的LAI_e在7月达到峰值(2.21),谷地云冷杉林、阔叶红松林的LAI_e在8月达到峰值,分别为2.57、2.68.白桦次生林、谷地云冷杉林、阔叶红松林的LAI_t均在7月达到峰值,分别为3.44、3.86、6.93;相对于本文探讨的方法,光学仪器所测定的LAI_e在最高叶面积指数期分别低估33.1%、32.9%、66.0%;而在整个调查期内,谷地云冷杉林和阔叶红松林LAI_e平均低估22.8%和56.5%,白桦次生林平均高估13.2%.
     

氮肥运筹对免耕水稻根系生长、根际土壤特性及产量的影响

为探索氮肥运筹对免耕条件下水稻根系生长以及对根际土壤特性、产量的影响,以金优253为材料进行试验。结果表明：平衡施肥显著提高单株根系干重、根长、单株生物量、根半径、单株根表面积、根长密度及根系活力,实收单产高于重穗肥和重基肥处理,且与重基肥差异达95％的显著水平,主要是有效穗数、结实率的增加。平衡施肥显著提高0~10 cm土层的0~2 mm根际土壤有机质、碱解氮含量及脲酶、蔗糖酶活性。因此平衡施肥能明显促进免耕水稻根系生长和有效穗数的增加,对提高水稻产量具有促进作用。