The effect of timing and severity of water deficit on growth,development, yield accumulation and nitrogen fixation of mungbean

Mungbean (Vigna radiata L.), as a dryland grain legume, is exposed to varying timing and severity of water deficit, which results in variability in grain yield, nitrogen accumulation and grain quality. In this field study, mungbean crops were exposed to varying timing and severity of water deficit in order to examine: (1) contribution of the second flush of pods to final grain yield with variable timing of relief from water deficit, (2) the sensitivity to water deficit of the accumulation of biomass and nitrogen (N) and its partitioning to grain, and (3) how the timing of water deficit affects the pattern of harvest index (HI) increase through pod filling. The results showed that the contribution of the second flush to final yield is highly variable (1–56%) and can be considerable, especially where mid-season stress is relieved at early pod filling. The capacity to produce a second flush of pods did not compensate fully for yield reduction due to water stress. Relief from mid-season stress also resulted in continued leaf production, N₂ fixation and vegetative biomass accumulation during pod filling. Despite the wide variation in the degree of change in vegetative biomass and N during pod filling, there were strong relationships between grain yield and net-above-ground biomass at maturity, and grain N and above-ground N at maturity. Only in the extreme situations were HI and nitrogen HI affected noticeably. In those treatments where there was a large second flush of pods, there was a pronounced biphasic pattern to pod number production, with HI also progressing through two distinct phases of increase separated by a plateau. The proportion of grain yield contributed to by biomass produced before pod filling varied from 0 to 61% with the contribution greatest under terminal water deficit. There was a larger effect of water deficit on N accumulation, and hence N₂ fixation, than on biomass accumulation. The study confirmed the applicability of a number of long-standing physiological concepts to the analysis of the effect of water deficit on mungbean, but also highlighted the difficulty of accounting for timing effects of water deficit where second flushes of pods alter canopy development, biomass and yield accumulation, and N dynamics.     

不同行距下两个花生品种的水分利用,生长发育和荚果产量

研究在本农艺学院开展,对每日平均气温、降水和光照均作记录。处理设六种不同株行距(0 .70×0 .12 ,0 .50×0 .12 ,0 .70×0 .06 ,0 .30×0 .12 ,0 .50×0 .06和0 .30×0 .06 m) ,对应密度是12 ,18 ,24 ,28 ,33和55株/ m2。测定0~100cm土壤样品水分含量,用于计算作物水分蒸发蒸腾量(ET)、作物光截获量(α)、土壤蒸发量(Es)、作物水分利用率( WUE)和蒸腾率(Te)。最低密度(0 .70×0 .12 m)单株生长最好,最高密度处理则导致最低的单株干物质产量,其余4个处理单株干物质产量居于二者之间。两个品种的不同间距处理同样对单株荚果饱果数、荚果和种子产量有显著影响,高密度下使其均降低,但单位面积荚果和种子产量提高,但Florman的产量要好于Colorado。种植处理显著影响作物水分蒸发蒸腾量。行距0 .30 m和0 .50 m下,两个品种都达到46和60 DAS;行距0 .70 m下,Colorado是66DAS而Florman是87DAS。两个品种的蒸腾率都受到行距的影响,两个品种的WUE都受到间距影响,0 .70 m行距下WUE最低,Colorado在0 .50 m和0 .30 m行距下,Florman在0 .30 m下WUE最高。行距对Te的影响因品种而异,Colorado在不同行距下无显著差异,而Florman的Te则随行距减少而增加。不同间距和品种对光合效率都没有很大影响(Colorado是3 .1×10-2Kcal/ha ,Florman是3 .0×10-2Kcal/ha)。     

花生(Arachis hypogaea L.)水分胁迫的研究Ⅰ. 开花与成针

为量化水分胁迫引起的花生物候学变化及其对开花和果针生长的效应,在阿根廷科尔多瓦省农牧学院试验农场开展了本研究.试验分两年(1997/98,1998/99)实施,随机区组设计,重复3次.试点为典型的Hapludol土,品种为Florman INTA,行株距分别为0.7和0.08m.在不同的生长时期(R1-R3, R3-R4, R4-R6, R6-R7)施以干旱处理(人工遮雨),持续时间为18～22d不等.测量土壤含水量并统计单株花朵数和果针数.结果证实了先前关于花生开花量和果针数对水分胁迫的反应的报道,也支持生殖生长延迟以及荚果发育和种子充实后期易受霜害的假说.     

Sunflower simulation using the EPIC and ALMANAC models

Modeling of sunflower (Helianthus annuus L.) is challenging because the crop species combines high yield potential with great adaptability. This paper surveys recent modeling-related research on sunflower phenology, growth, and yield. Simulations of sunflower by two closely related models, and almanac, are described. Phenology was predicted with growing degree days with a 6°C base temperature (GDD₆) summed from sowing to maturity, assuming anthesis occurred when 0.62 of the total GDD₆ had accumulated. Growth simulation involved leaf area index (LAI) development, light interception and radiation-use efficiency (RUE). Inclusion of a vapor pressure deficit (VPD) effect appeared to make RUE more general. A modified harvest index approach was used to simulate seed yields. The and models gave reasonable yield simulations over a wide range of environments and management options. The models should be valuable both for assessing the impacts of different management schemes and for identifying subject areas where additional basic research is needed.     

Predicting growth and development of pigeonpea: biomass accumulation and partitioning

Examining physiological relationships that quantify the processes of interception of radiation and biomass accumulation and partitioning provide one avenue for understanding limits to pigeonpea productivity. The radiation extinction coefficient (k), radiation use efficiency (RUE), partitioning of biomass between leaf and stem before flowering, and the rate of linear increase in harvest index (HI) during pod-filling were determined for nine cultivars in water and nutrient non-limiting conditions at ICRISAT Centre, Patancheru, India. The nine cultivars comprised three each from the cultivar duration classes extra-short (100 days to maturity), short (115 days) and medium (170 days). Values of k and RUE were consistent across duration groups, with mean values of 0.53 and ca. 0.9 g MJ⁻¹, respectively. RUE remained at its maximum value almost until maturity. Partitioning between leaf and stem prior to flowering was also consistent across groups, in the ratio of 1:1.03 to 1:1.14. The rate of linear increase in HI and final HI varied across groups, with lower rates of partitioning to grain and final HI in the later maturing groups. When adjusted for fallen leaf, the HI increase was ca. 0.08, 0.075 and 0.04 per day, and maximum HI was ca. 0.35, 0.32 and 0.19 for extra-short, short and medium-duration groups, respectively. The association of lower HI increase with indeterminate growth provides a convenient framework to simulate concurrent reproductive and vegetative growth during pod-filling.     

不同时期水分胁迫对御旱基因型大豆光合特性的影响

盆栽条件下,以御旱型辽豆14和干旱敏感型辽豆21为研究对象,设置干旱、轻度干旱和适宜水分三个处理,探讨不同生长时期控水条件下,御旱型大豆植株光合特性和叶绿素荧光特性变化的特征和规律,以期揭示御旱基因型大豆抗旱的光合调控机理。结果表明：各个时期控水,土壤水分都显著影响大豆植株的净光合速率（Pn）、蒸腾速率（Tr）、气孔导度（Gs）;干旱限制了植株的Pn、Tr、Gs、胞间CO₂浓度（Ci）,辽豆21的蒸腾速率平均值高于辽豆14。随着土壤含水量的增加,植株Ci浓度逐步提高。土壤干旱条件下的初始荧光（F₀ ）值最大,结荚期（R3-R5）控水时F₀ 值最低。干旱胁迫降低了植株的最大光化学效率（Fv/Fm）、电子传递效率（ETR）和实际光化学效率（Φ_PSⅡ ）。同一时期控水,御旱基因型辽豆14的最大荧光产量（Fm）和Fv/Fm高于辽豆21的值。干旱胁迫下,御旱基因型辽豆14能够维持较低的蒸腾速率,较高的Fm和Fv/Fm值,这可能是御旱型辽豆14抗旱的重要原因。     

Physiology of yield determination of mung bean (Vigna radiata (L.) Wilczek) under various irrigation regimes in the dry and intermediate zones of Sri Lanka

Drought is a major factor limiting yield improvement of mung bean (Vigna radiata (L.) Wilczek) in the sub-humid, dry and intermediate zones of Sri Lanka. Therefore, the objective of this study was to analyze the yield response of mung bean to irrigation at various phenological stages in terms of radiation interception, radiation-use efficiency and harvest index. Four field experiments were carried out at two sites (Maha-Illuppallama and Kundasale) during the short, dry yala season over two years (1995 and 1996). The life cycle of mung bean was divided into three stages: vegetative (from germination to appearance of first flower); flowering (from appearance of first flower to 75% pod initiation); and pod-filling (from 75% pod initiation to maturity). Eight irrigation treatments were defined as all possible combinations of irrigation during the three stages. Maximum potential soil water deficits (PSWD) ranging from 127 to 376 mm developed as a result of keeping different combinations of stages unirrigated. Maximum LAI (L_m) and the fraction of incoming radiation intercepted (F) increased significantly with the number of stages irrigated. Specifically, treatments which included irrigation during the vegetative stage achieved large L_m and F. Radiation-use efficiency (RUE), maximum total biomass (W_m), harvest index (HI) and seed yield (Y) also showed a significant positive response to the number of stages irrigated. However, all the above parameters were significantly greater in treatments which included irrigation during the pod-filling and flowering stages. The treatment which received irrigation only during the vegetative stage had significantly lower RUE, W_m, HI and Y despite having higher L_m and F. Therefore, irrigation is critical during pod-filling and flowering stages mainly because of the higher LAI during these periods and, consequently, the greater demand for water. Lack of irrigation during these critical stages resulted in the development of significant PSWD with adverse effects on photosynthesis and consequently decreased RUE. Moreover, water stress during flowering and pod-filling stages significantly reduced pod initiation and pod growth rates and thereby reduced HI. It is concluded that to maximize mung bean yields in the dry season of the sub-humid zones of Sri Lanka, irrigation should extend across all phenological stages, specially the pod-filling stage.     

Environmental effects on seed yield determination of irrigated peanut crops: Links with radiation use efficiency and crop growth rate

In Argentina, delayed sowing causes a decrease in seed yield and in radiation use efficiency (RUE) of peanut crops (Arachis hypogaea L.), but it is not known if RUE reduction is mainly due to reduced temperature during late reproductive stages or to a sink limitation promoted by decreased seed number in these conditions. We analyzed seed yield determination and RUE dynamics of two cultivars (Florman and ASEM) in four irrigated field experiments (Exp_n) grown at three sites and five contrasting sowing dates (between 17 October and 21 December) in three growing seasons. An additional field experiment was performed with widely spaced plants (i.e. with no interference among them) to evaluate the effect of peg removal on RUE and leaf carbon exchange rate (CER). Seasonal dynamics of mean air temperature and irradiance, biomass production (total and pods), and intercepted photosynthetically active radiation (IPAR) were followed. Seed yield and seed yield components (pod number, seeds per pod, seed number and seed weight) were determined at final harvest. Crop growth rate (CGR) and pod growth rate (PGR) were computed for growth phases of interest. RUE values for crops sown until 14 November were 1.89–1.98 g MJ⁻¹ IPAR, within the usual range. RUE decreased significantly for cv. Florman in the late sowing of Exp₁ (29 November) and for both cultivars in Exp₃ (21 December sowing). Across experiments, seed yield (4.5-fold variation relative to minimum) was strongly associated (r² = 0.87, P < 0.0001) with variations in seed number (3.5-fold variation relative to minimum), and to a lesser extent (r² ≤ 0.54, P ≤ 0.001) to variations in seed weight (1.9-fold variation relative to minimum). Seed number was positively related (P < 0.01) to CGR (r² = 0.66) and to PGR (r² = 0.72) during the R₃–R_6.5 phase (seed number determination window), while crop growth during the grain-filling phase (i.e. between R_6.5 and final harvest) was positively associated with grain number (r² = 0.80, P < 0.001). No association was found between RUE and mean air temperature, neither for the whole cycle nor for the phase between R_6.5 and final harvest, which showed the largest temperature variation (16.4–22.4 °C) across experiments. Use of mean minimum temperature records (range between 13.8 and 18.5 °C) did no improve the relationship. However, grain-filling phase RUE showed a positive (r² = 0.69, P = 0.003) linear response to seed number across experiments. This apparent sink limitation of source activity was consistent with the reduced RUE (from 2.73 to 1.42 g MJ⁻¹ IPAR) and reduced leaf CER at high irradiance (from ca. 30 to 15 μmol m⁻² s⁻¹) for plants subjected to 75% peg removal.     

Leaf inoculation as an early screening test for cocoa (Theobroma cacao L.) resistance to Phytophthora black pod disease

In this study a leaf inoculation method was used to standardize a bioassay for testing the genetic susceptibility (or resistance) of cocoa cultivars to black pod disease caused by Phytophthora palmivora and Phytophthora megakarya. Both whole leaves and leaf discs from non-lignified twigs, were suitable for inoculation with suspensions of 3 × 10⁵ zoospores/ml. Cocoa clones tested for resistance to black pod with leaf bioassays responded in the same rank order as reported for fruit inoculation in the literature. Furthermore, the rank of a cultivar within the classification stabilizes between 5 and 7 days after inoculation. The leaf bioassay for susceptibility of hybrid families, demonstrated a highly significant plant effect within the family, so that comparison between families was of limited value. Leaf bioassays enabled early and rapid selection of cocoa cultivars resistant to black pod disease, provided the method was strictly standardized and that results are compared with those from fruit inoculations reported in the literature.     

籼型杂交稻恢复系动态株型与光能利用率评价

【目的】理想株型是水稻高产稳产的前提。本研究拟对不同年代育成的籼型三系杂交稻恢复系动态株型与光能利用效率进行综合评价,探讨恢复系光能高效利用的理想动态株型特征,为提高光能高效利用的高产稳产杂交稻育种效率提供理论依据。【方法】以明恢63、明恢82、蜀恢527、广恢998、广恢122、广恢128、广恢308和桂99等8个大面积应用的籼型杂交稻恢复系为供试材料,在华南生态条件下考查了其分蘖、叶面积指数(LAI)、透光率、叶片大小与开张角、叶色(SPAD值)等性状的动态变化,以及抽穗期光合速率、生育期、产量相关性状和光能利用率(RUE)等指标。【结果】各恢复系之间在株型动态变化、产量和光能利用率(RUE)等方面存在较大差异。良好的动态株型与光能利用率密切相关,最为接近华南生态条件下理想动态株型的广恢998和广恢308,光能利用率最高。根据聚类分析,广恢998、广恢308和明恢82属于光能高效利用的类群Ⅰ。其他恢复系归为类群Ⅱ。最后,根据华南的光温生态特点,提出了水稻光能高效利用的理想动态株型模式及育种选择关键指标：1)移栽后分蘖和叶面积发展快,LAI达到1.0的时间≤27 d;茎蘖数达到峰值所需时间≤38 d,分蘖力中等,最高茎蘖数≤600苗/m²;2)前期窄叶长披,移栽后15 d顶部3片完全叶平均长度为37 cm,平均宽度≤0.9 cm,开张角度≥80°;后期叶片窄直,抽穗后20 d顶部倒3叶平均开张角≤65°,平均长度为43 cm,平均宽度≤1.3 cm,属于中叶型,有利于后期群体通风透光;3)后期叶片转色好,不早衰,SPAD值维持在35~40,抽穗前20 d至抽穗后20 d之间的叶片SPAD值降幅≤13%;普通栽培条件下平均每穗总粒数180粒左右,有效穗数300穗/m²以上,结实率≥85%。【结论】广恢998和广恢308具有较为理想的动态株型和较高RUE,利用其配制的杂交稻天优998、博优998和五优308等连续多年成为我国华南稻区主导品种和国家与省级区试对照品种。说明通过选育光能高效利用的理想动态株型恢复系,是组配选育高产稳产杂交稻行之有效的重要途径。     

大豆GmLecRlk基因耐盐功能分析

凝集素类受体蛋白激酶属于类受体蛋白激酶（RLKs）家族,在植物的抗病防御反应、生长发育、胞内信号传导以及非生物胁迫反应过程中发挥重要作用。实验室前期对过表达抗逆转录因子GmNFYB1大豆进行转录组测序,获得了差异表达基因GmLecRlk（Glyma.07G005700）,其开放阅读框长度为546 bp,编码181个氨基酸,蛋白结构域分析显示其含有两个丝氨酸/苏氨酸激酶结构域,属于一种G型凝集素类受体蛋白激酶。实时荧光定量PCR结果显示,GmLecRlk基因在大豆的根、茎、叶、荚中均有不同程度的表达,在根中表达量最高;200 mmol/LNaCl处理下,GmLecRlk 的mRNA丰度先降低后升高,在12 h时达到最高值,表明该基因参与大豆对盐胁迫的响应。利用发根农杆菌K599获得GmLecRlk过表达转基因发状根复合植株,在盐胁迫处理下,其存活率高于对照;在拟南芥中异源表达GmLecRlk基因,转基因拟南芥在盐胁迫处理下的萌发率、绿化率和根长均高于野生型拟南芥。综上所述,GmLecRlk参与大豆对盐胁迫的反应,过量表达基因能提高大豆和拟南芥的耐盐性,为培育和改良抗盐大豆新品种提供新的途径和理论指导。     

假木豆属种质资源植物学性状遗传多样性分析

假木豆（Dendrolobium triangulare）为多年生灌木,假木豆叶量大、产量高,营养价值高,是优良的高蛋白青饲料。目前仅有山蚂蝗亚族之间的遗传多样性研究,假木豆属的形态学遗传多样性的分析研究比较匮乏,缺少大范围的种质形态学遗传多样性研究。对优质育种资源植物学性状综合评价是育种的前提。为了培育优质豆科牧草品种,满足南方畜牧生产需求,本研究采用随机区组设计,研究材料为76份假木豆属种质资源,对35个植物学性状进行观测,分析假木豆属的遗传多样性特点,为假木豆选育工作提供基础材料。通过形态学观测分析研究其遗传多样性,结果表明：35个植物学性状中叶背面毛况（CV=46.92%）,茎的颜色（CV=39.77%）和叶柄毛况（CV=39.52%）变异系数（CV）最大,说明假木豆属遗传多样性较为丰富;多个植物学性状之间存在相关性,叶长与叶宽（r=0.887）之间存在极显著正相关,长宽比在2.0左右,叶形比较接近椭圆形。茎的形状与叶长（r=–0.459）、叶宽（r=–0.491）存在相关性,这表明如果假木豆产量以叶面积为主,应尽量选择圆柱形的茎。中央小叶叶形与荚果长（r=0.360）存在极显...     

孕穗期冷水胁迫下施用外源物质对寒地粳稻氮光合效率及产量的影响

【目的】制定减灾保产化控栽培技术,有效抵御寒地粳稻孕穗期低温冷害。【方法】采用裂区试验设计和中心组合试验设计,基于产量相关指标隶属函数值,筛选出寒地粳稻孕穗期冷水胁迫下氯化钙(CaCl₂)、谷氨酸(Glu)、γ-氨基丁酸(GABA)三种外源物质最适施用浓度及其最适浓度配比,并研究孕穗期冷水胁迫下施用最适浓度配比三种外源物质(CGG)对寒地粳稻氮光合效率及产量形成的影响。【结果】1)孕穗期冷水胁迫下施用CGG最适浓度配比为1.87 mmol/L CaCl₂、2.76 mg/LGlu、4.40 mmol/L GABA,隶属函数平均值最大(0.932)。2)与正常灌溉相比,孕穗期低温胁迫下寒地粳稻氮光合效率下降;与孕穗期冷水胁迫相比,施用最适浓度配比CGG可显著提高东农428齐穗期叶面积指数(5.37%)及氮光合效率(4.53%);可显著提高松粳10齐穗期单位面积叶片干物质量(2.56%)和叶面积指数(3.39%)。3)与孕穗期冷水胁迫相比,施用最适浓度配比CGG可提高寒地粳稻抽穗至成熟期干物质积累量,但其积累量仍低于正常灌溉水平,且在品种和处理间存在差异。4)与孕穗期冷水胁迫相比,施用最适浓度配比CGG寒地粳稻产量及产量构成因素均有所上升,但仍低于正常灌溉水平,且对冷敏感的品种影响更为显著。5)与孕穗期冷水胁迫相比,施用最适浓度CGG东农428和松粳10温度生产效率平均增幅分别为5.55%和23.72%。外源CGG对于温度生产效率差异的贡献率为8.99%。【结论】孕穗期冷水胁迫下施用最适浓度配比CGG可通过促进齐穗期叶片生长,进而提高群体氮光合效率,有利于抽穗后干物质积累及产量形成,减轻孕穗期冷水胁迫对寒地粳稻产量造成的损失,提高寒地粳稻温度生产效率。     

Increased frequency of phytosanitary pod removal in cacao (Theobroma cacao) increases yield economically in eastern Peru

Diseases caused by Moniliophthora roreri (moniliasis), Crinipellis perniciosa (witches’ broom) and Phytophthora palmivora (black pod) are the most important factors limiting cocoa production in Peru and cultural management is considered to be the only practical means of control for the smallholder. The objective of this study was to develop an epidemiologically and economically sound control recommendation based on the frequency of phytosanitary pod removal. Weekly removal of diseased pods reduced the incidence of diseases significantly in comparison with fortnightly removal. In three fields, moniliasis was decreased by 26–41%, black pod by 35–66% and witches’ broom on pods by 14–57%. The cumulative effect was a consistent yield increase from an average of 504–660 kg ha⁻¹ yr⁻¹. Returns compensated for increased labour costs. Weekly pod removal was 32% more profitable. Time-course analyses indicated that weekly removal should be practised throughout the year under field conditions of eastern Peru.     

Comparisons of radiation use efficiency of mono-/inter-cropping systems with different row orientations

Intercropping may be helpful to solve future food problem in developing countries. The aim of this study was to compare production efficiency in intercropping with sole cropping in terms of radiant energy use. For analysing crop radiation capture and utilisation, three indices are often used: the fraction of radiation intercepted (F), radiation use efficiency (RUE) and harvest index (HI). Using those indices, maize–bean intercropping was evaluated and compared with maize and bean sole cropping systems. The findings were as follows: the intercrop F was higher than the sole crop F, the sole maize RUE was higher than the others, and there was no difference in HI among cropping systems. From those results, the intercropping may be equivalent to maize sole cropping in the overall efficiency of radiation interception and use. Therefore, when it is considered that both maize and beans would be planted in a given area of land, intercropping has more efficient radiation harvests than sole cropping. No effect of row orientation was found on F, RUE and HI.     

花生不同株型主要农艺性状的相关分析及其对单株产量的影响

以粤油13为供试材料,通过3种不同直径的管环处理,创制不同株型。本研究统计分析了18个主要农艺性状的相关性;采用通径分析的方法对单株产量进行通径分析;然后进行单株产量的逐步回归分析。农艺性状分析结果表明,单株产量、最大果节数、侧枝长、单株总果数、单株饱果数随着处理直径的增大显著增加;相关分析表明,单株产量与侧枝角度、最大果节数、单株总果数和单株饱果数呈极显著正相关;通径分析表明,单株总果数对单株产量的直接通径系数最大(PY.X7=2.15),而在株型相关性状中,侧枝角度具有较大的间接效应(IEX2=0.8567),在侧枝角度影响单株产量的间接因素中,通过影响单株总果数的间接效应最大(IEX2.X7=1.2060)。通过逐步回归分析,分别建立了单株产量的最优回归方程:Y=8.43+0.53X2 (P=6.8E-5);Y=-29.26+1.26X8+0.22X7 (P=3.13E-19;P=4.06E-11),为单株产量预测提供理论参考。本研究初步解析了花生株型与产量之间的关系,初步探明了株型相关性状对产量的影响因素,提出了培育具有"U"型特征的花生新株型品种,可为花生株型育种提供一定的理论依据。     

Screening of allelochemicals on barnyardgrass (Echinochloa crus-galli) and identification of potentially allelopathic compounds from rice (Oryza sativa) variety hull extracts

Experiments were conducted to screen 23 known allelochemicals, including sinapic acid, and an equimolar mixture of the chemicals for potential allelopathy on barnyardgrass (Echinochloa crus-galli var. oryzicola), and to identify allelochemical(s) from hull extracts from three rice (Oryza sativa L.) cultivars. In a bioassay, the inhibitory effect was increased as the concentration of allelochemicals increased from 10⁻⁵ to 10⁻³ M. Ferulic, p-hydroxybenzoic, p-coumaric, and m-coumaric acids were the most active compounds and caused the greatest effect on seed germination, germination rate, and total seedling dry weight reduction. p-hydroxybenzoic acid (10⁻³ M; pH 4.1) showed the greatest inhibitory effect on the same parameters. HPLC analysis using three rice cultivars, Janganbyeo, Baekambyeo, and Labelle, showed that the concentration and composition of potentially allelopathic compounds depended upon the cultivar. Hull extracts from the allelopathic cultivar Janganbyeo contained higher levels of p-hydroxybenzoic acid than did those of the non-allelopathic cultivars Labelle and Baekambyeo. Nine compounds, including p-hydroxybenzoic acid (4.29 mg/g) in Janganbyeo, seven compounds including m-coumaric (0.43 mg/g) in Labelle, and five compounds including p-hydroxybenzoic acid (0.36 mg/g) in Baekambyeo, were detected. Preliminary identification by HPLC analysis resulted in peaks with retention times near those of standards, including p-hydroxybenzoic acid that was confirmed with EI/MS. It is suggested that these compounds may be, at least, a key factor in rice allelopathy on barnyardgrass, and the information presented may contribute to the development of naturally occurring herbicides.     

磷酸盐转运蛋白OsPT4影响水稻氮磷积累与利用的机理研究

【目的】磷酸盐(Pi)转运蛋白OsPT4是水稻Pht1家族成员之一,负责Pi吸收以及向地上部的转运。探究OsPT4超表达对不同Pi条件下水稻氮(N)和磷(P)积累与利用的影响及其机理具有重要意义。【方法】以日本晴背景的OsPT4超表达株系为研究材料,通过设置正常供Pi与缺Pi的水培与桶培实验,检测生殖生长阶段不同组织中OsPT4的相对表达量,探究不同Pi处理条件下不同组织(叶片、叶鞘、茎秆、稻壳、穗柄和糙米)中的N和P浓度,并计算Pi吸收率及N和P利用效率,同时分析株高、单株产量、千粒重和结实率等产量构成因素。【结果】OsPT4在水稻生殖生长阶段的根系中相对表达丰度较高,OsPT4超表达使水稻剑叶、叶鞘、茎秆、稻壳、穗柄和糙米中的总P浓度不同程度提高,并显著提高了不同Pi处理条件下的Pi吸收与利用效率。同时,OsPT4的超表达可显著提高正常供Pi与缺Pi土壤条件下的单株产量与千粒重,以及缺Pi土壤中生长的结实率。除此之外,OsPT4的超表达使缺Pi条件下瘪壳与糙米中总N浓度平均升高16.8%和19.8%,N利用效率平均升高6.6%。【结论】OsPT4超表达不仅显著提高Pi吸收与利用效率,同时对不同Pi条件下的生理氮素利用率起促进作用。     

花叶鹅掌柴不同颜色叶片光合特性

以多年生花叶鹅掌柴(Schefflera odorata cv.Variegata)成年植株为试验材料,选择同一植株上的3种颜色叶片,分别为全绿叶(whole green leaf,WGL)、花叶(variegated leaf,VL)和黄叶(whole yellow leaf,WYL),测定其光合色素含量、光响应曲线...     

低温胁迫对不同甘蔗品种叶片光合色素和光合生理特性的影响

以4个抗寒能力不同的甘蔗品种(系)作为研究材料,分析光合色素含量与构成以及采用叶绿素荧光成像技术探究低温对甘蔗光合生理特性的影响。结果表明:耐寒性强的GR2、GT28叶片单位面积叶绿素a含量分别比ROC22高13.74%、10.39%,其叶片F_v'/F_m'分别高3.25%、3.01%,且这差异随着胁迫时间延长逐渐明显,而Φ_psⅡ和qP也具有相同的变化趋势;GR2、GT28叶片的单位面积类胡萝卜素含量分别比ROC22高22.73%、19.36%,其叶片NPQ分别高20.33%、12.17%,且NPQ随着胁迫延长快速升高;甘蔗在早期响应阶段(0～24 h)单位叶面积的光合色素含量基本不变,而叶片的F_v'/F_m'、Φ_psⅡ和qP受到抑制却迅速降低后并维持相对稳定,相反NPQ急速升高;在胁迫适应阶段(24～168h),叶片光合色素因为低温造成的合成受阻及结构破坏,其叶片F_v'/F_m'、Φ_psⅡ和qP在(24～72 h)处理期间再次大幅降低,但在(72～168 h)处理阶段光能吸收、利用及耗散份额保持相对平稳,而NPQ先急剧升高后逐渐趋于平缓,说明低温胁迫下甘蔗通过调节光合色素含量及在PSⅠ和PSⅡ的反应中心复合体的结合比例以加快耗散过剩的激发能,是植物(作物)在低温逆境条件其光合机构对光能吸收及利用的调节也是一种重要的保护策略。