光合营养素的研制与开发

以荔枝、龙眼、番荔枝、台湾青枣、番石榴等果树品种为试材 ,广州市果树研究所研发了一种适用于多种果树、含多种有机营养成分的生物有机营养产品———光合营养素。试验和应用结果表明 ,喷施光合营养素可显著提高岭南名优水果的光合效能 ,提高座果率、改善果实品质、增加产量 ,显著提高种果经济效益 ,具有较高的应用推广价值。①使妃子笑荔枝叶片光合速率提高2 8 3% - 42 % ,果实可溶性固形物含量提高 1 1个百分点 ,单果重由 2 5 7克增加到 2 7 8克 ,单株产量提高 12 5 %和 14 3% (石硖龙眼 ) ,尤其是在缺阳光的阴雨天气 ,喷施效果更为明显。②有效加快叶片老熟 ,提高叶片叶绿素含量。喷施后 ,妃子笑叶绿素含量提高 6 2 % ,达到P =0 0 1差异显著水准 ,AP番荔枝、毛叶枣、新世纪番石榴的叶绿素含量分别提高 18 1%、 15 3%和 11 2 %。

黄花杓兰与菌根真菌共生关系研究

对黄花杓兰 (CypripediumflavumP .F .HuntetSummerh .)植株的根进行了一个生长周期的采集和切片观察 ,发现黄花杓兰具有相应的菌根结构 ,菌丝的存在状态在各物候期有所不同 ,可分为 5个时期 :(1) 4月份联通菌丝时期 ;(2 ) 5月份菌丝团时期Ⅰ ;(3) 6、 7月份无菌丝团时期Ⅰ ;(4 ) 8、 9月份菌丝团时期Ⅱ ;(5 ) 10月份无菌丝团时期Ⅱ。可以看出 ,在植株生活转变期 ,根细胞内出现菌丝团 ;在植株完成正常的生命过程中 ,真菌营养是光合营养的补充 ;真菌菌丝团也作为植物营养的储存器 ,菌丝团消解释放营养供给植株。在此基础上探讨了菌根真菌与黄花杓兰的共生关系的一个方面 :植株通过联通菌丝沟通各个细胞的物质交换 ,菌根真菌利用植株体内物质完成生命活动 ,菌丝团消解 ,使真菌所储藏的营养物转化 ,为植株所利用。

Effects of Different Levels of Phosphorus Nutrient on the Photosynthesis Characteristic of Rice Flag Leaf

[Objective] To provide scientific basis for high phosphorus efficiency cultivation and regulation of rice. [Method] Changbai9 （CB9） and Jijing81 （JJ81） were used as experimental materials for pot experiment, and five levels of phosphorus nutrient （ Po - P4 ） were set for each variety, the net photosynthesis rate, Chlorophyll Meter Readings （SPAD Readings）, stomatal conductance, transpiration rate, intercellular CO2 concentration, and stomatal limitation were observed and compared between five different phosphorus levels at filling stage. [ Result] The net photosynthesis rate of CB9 reached the highest at P3, and was significantly different from other treatments （P 〈0.05）;the net photosynthesis rate of groups with phosphorus of J J81 were higher than that of the control group,and reached the highest at P,. The SPAD Readings of CB9 and JJ81 all achieved the highest at P3, and stomatal conductance and transpiration rate were all at first increased then decreased with the phosphor- us increased in CB9 and JJ81. With the phosphorus increased, intercellular CO2 concentration of CB9 decreased at first and then increased, while in JJ81 the trend was inversed,but the tendency of intercellular CO2 concentration were opposite to that of stomatal limitation in both culti- vars. [ Conclusion] Appropriate adding phosphorus could improve photosynthetic characteristic of rice flag-leaf,but displayed significant genotypic difference.

Gas Exchange, Xylem Ions and Abscisic Acid Response to Na^+-Salts and Cl^--Salts in Populus euphratica

We investigated the osmotic stress and ion-specific effects on xylem abscisic acid (ABA), ion uptake and transport and gas exchange in one-year-old seedlings of Populus euphratica Oliv. Net photosynthetic rates (P-n) and unit transpiration rates (TRN) were both significantly decreased upon an osmotic shock caused by PEG 6000 solution (osmotic potential = -0.24 MPa) or a saline, which was applied by 50 mmol/L Na+-salts (NaNO3 : NaHCO3 : NaH2PO4 = 5 : 4 : 1, pH 6.8, osmotic potential = -0.24 MPa) or by 50 mmol/L Cl--salts (KCl : NH4Cl = 1:1, osmotic potential = -0.24 MPa). However, salt-treated P. euphratica plants maintained typically higher TRN than those exposed to PEG. Xylem ABA concentrations increased rapidly following the PEG treatment, exhibiting peaking values at 1 h, then returning to pre-stress levels, followed by a gradual increase. Similarly, both Na+-treated and Cl--treated trees exhibited a rapid rise of ABA after salt stress was initiated. Notably, salt-treated plants maintained a relatively higher ABA than PEG-treated plants in a longer term. Collectively, results suggest that osmotic stress and ion-specific effects were both responsible for salt-induced ABA in P. euphratica : the initial rapid increase of xylem ABA appears to be a consequence of an osmotic shock, whereas specific salt effects seem to be responsible for ABA accumulation later on. Compared with Cl--treated trees, a higher inhibitory effect on gas exchange (P-n and TRN) was observed in Na+-salt plants, resulting from its long-sustained ABA and higher salt concentrations in the xylem. Displacement of membrane-associated Ca2+ by Na+ and the lesser capacity in Na+ compartmentation in root vacuoles likely contribute to the high influx of Na+ and Cl- in Na+-treated plants. Xylem K+, Ca2+ and Mg2+ concentrations were elevated by external Na+ -salts and Cl--salts, suggesting that P. euphratica maintained a higher capacity in nutrient uptake under saline conditions, which makes a contribution to its salinity tolerance.

Characterization of high-yield performance as affected by genotype and environment in rice

We characterized yield-relevant characters and their variations over genotypes and environments （locations and years） by examining two rice varieties （9746 and Jinfeng） with high yield potential. 9746 and Jinfeng were planted in two locations of Shanghai, China, during 2005 and 2006. The results show that there was a large variation in grain yield between locations and years. The realization of high yield potential for the two types of rice was closely related to the improved sink size, such as more panicles per square meter or grains per panicle. Stem and leaf biomasses were mainly accumulated from tillering stage to heading stage, and showed slow decline during grain filling. Meanwhile, some photosynthetic characters including net photosynthesis rate （Pn）, leaf area index （LAI）, specific leaf area （SLA）, fluorescence parameter （maximum quantum yield ofPSll, Fv/Fm）, chlorophyll content （expressed as SPAD value）, as well as nutrient （N, P, K） uptake were also measured to determine their variations over genotypes and environments and their relationships with grain yield. Although there were significant differences between years or locations for most measurements, SLA at tillering and heading stages, Fv/Fm and LAI at heading stage, stem biomass at heading and maturity stages, and leaf nitrogen concentration at tillering and heading stages remained little changed, indicating their pos- sible applications as selectable characters in breeding programs. It was also found that stem nitrogen accumulation at tillering stage is one of the most important and stable traits for high yield formation.

Photosynthetic efficiency, cell volume, and elemental stoichiometric ratios in Thalassirosira weissflogii under phosphorus limitation

Nutrient limitation is known to inhibit growth and metabolism and to alter elemental stoichiometric ratios in phytoplankton. In this study, physiological changes in Thalassirosira weissflogii were measured under different dissolved inorganic phosphate (DIP) regimes in semi-continuous cultures to revisit the utility of the Redfield ratio for assessing nutrient limitation. The results showed that cell size increased with decreasing DIP availability. In the P-depleted treatment (f/2-P) the cell size was 1.48 times larger than that in the P-limited (f/100) treatment and 2.67 times larger than that in the P-saturated treatment (f/2 and f/10). The fucoxanthin to chlorophyll a ratio (Fuco/chl a) was relatively stable (about 0.3) in P-saturated cultures and was 10 times higher than that in P-limited and P-depleted cultures. During the experimental period, the photosynthetic efficiency index, ?F/Fm′, was relatively stable at ~0.50 in the P-saturated cultures, but quickly declined with decreasing DIP availability. Although cellular P content showed a significant difference between the P-saturated culture (1.6 pg/cell) and the P-limited culture (0.7 pg/cell), the N/P ratio in T. weissflogii did not show a trend with DIP availability and fluctuated slightly around 25. Our results suggest that cell division in T. weissflogii is not strictly size-gated but is probably regulated by a biochemical, and hence, an elemental stoichiometric ratio threshold, and that deviation of the cellular N/P ratio from the Redfield ratio is not a reliable indicator of algal nutrient stress.

Effects of elevated CO_2 on the photosynthesis and nitrate reductase activity of Pyropia haitanensis(Bangiales,Rhodophyta) grown at different nutrient levels

Pyropia haitanensis, a commercially important species, was cultured at two CO2 concentrations （390× 10^-6 and 700× 10^-6 （parts per million）） and at low and high nutrient levels, to explore the effect of elevated CO2 on the species under nutrient enrichment. Results show that in CO2-enriched thalli, relative growth rate （RGR） was enhanced under nutrient enrichment. Elevated CO2 decreased phycobiliprotein （PB） contents, but increased the contents of soluble carbohydrates. Nutrient enrichment increased the contents of chlorophyll a （Chl a） and PB, while soluble carbohydrate content decreased. CO2 enrichment enhanced the relative maximum electronic transport rate and light saturation point. In nutrient-enriched thalli the activity of nitrate reductase （NRA） increased under elevated CO2. An instantaneous pH change in seawater （from 8.1 to 9.6） resulted in reduction of NRA, and the thalli grown under both elevated CO2 and nutrient enrichment exhibited less pronounced reduction than in algae grown at the ambient CO2. The thermal optima of NRA under elevated CO2 and/or nutrient enrichment shifted to a lower temperature （10-15 ℃） compared to that in ambient conditions （20℃）. We propose that accelerated photosynthesis could result in growth increment. N assimilation remained high in acidified seawater and reflected increased temperature sensitivity in response to elevated CO_2 and eutrophication.

Effects of different phosphorus concentrations and N/P ratios on the growth and photosynthetic characteristics of Skeletonema costatum and Prorocentrum donghaiense

The effects of different phosphorus(P) concentrations(0.36, 3.6, and 36 μmol/L corresponding to low-, middle-, and high-P concentration groups, respectively) and nitrogen(N)/P ratios on the growth and photosynthetic characteristics of S keletonema costatum and Prorocentrum donghaiense were studied. For both species, the high-P(HP) concentration group showed the greatest algal density and highest specifi c growth rate. Changes in the maximum effi ciency of photosystem Ⅱ(F _v/F_m) were monitored under the various P and N/P conditions. The largest decrease in F _v/F_m was in the low-P(LP) group in S. costatum and in the HP group in P. donghaiense. There were high rapid light curves and photochemical quantum yields(Φ _(PSⅡ)) for S. costatum in the HP group, while the actual photosynthetic capacity was higher in P. donghaiense than in S. costatum in the MP group. Under eutrophic but relatively P-restricted conditions, P. donghaiense had higher photosynthetic activity and potential, which could cause this dinofl agellate to increasingly dominate the phytoplankton community in these conditions. Under the same P concentration and N/P ratio, P. donghaiense had a larger relative maximum rate of electron transport and higher Φ _(PSⅡ) values than those of S. costatum. These differences between P. donghaiense and S. costatum may explain the interaction and succession patterns of these two species in the Changjiang(Yangtze) River estuary from a photosynthesis perspective.

Application of NaHCO_3/ DTPA Extractant-ICP Spectrometry Technique in Soil Test for Availability of Nutrients and Heavy Metals

Soil test for availability of nutrients and heavy metals is extensively served as a means for the evaluations of soil fertility, and environmental effects and phytotoxicity of pollutants in soils, and for the fertilizer recommendation in agricultural and environmental sciences. Therefore, great attention has been paid to the measurement of elemental availability in soil test.

Photosynthetic Carbon Gain, Allocation and Resources-Use Efficiency in Invasive Eupatorium Adenophorum and Its Native Congener E. Japonicum under Different Light and Nutrient Conditions

Invasion is often facilitated by high resources availabilities and suppressed under low resources habitats. However, a number of invasive plants can successfully establish and dominate in resource-poor and （or） the understory of closed forests, indicating the plant＇s performances are habitats-dependent and species-specific. It is therefore necessary to explore the ecophysiological characteristics associated invasiveness for one invasive species across multiple resources availabilities whilst taking the relatedness into these comparative studies. In this study, invasive Eupitorium adenophorum and its native congener E. japonicum grew under different resource gradients in terms of light levels and soil nitrogen additions to identify the functional significance morphological and physiological traits associated closely with invasion and to examine their comparative responses. Photosynthetic carbon gain, biomass allocation and resource-use efficiency are evaluated in this pot experiment. Across treatments, E. adenophorum exhibited consistently higher values for most of the morphological variables including plant stature, relative growth rate （RGR）, leaf root ratio （LRR）, leaf area ratio （LAR）, total leaf area, and lower root： shoot ratio （RSR）. Significantly higher Pmax corresponded with higher photosynthetic nitrogen use efficiency （PNUE） and photosynthetic energy use efficiency （PEUE） especially in low light and （or） unfertile condition. Higher Gs and Pmax but lower photosynthetic water use efficiency （WUE） indicated the trade-off relationship between WUE and PNUE for E. adenophorum. Final biomasses were higher for E. adenophorum in nutrient and（or） light limited conditions, in which higher leaf construction cost（CC） compared with E. japonicum could be over-compensated by its significantly higher assimilation rates. The effects of light levels on these plant attributes were stronger than soil nutrient contents. The responses of these two congeneric species to light and nitrogen availabilities were similar, but the differences were magnified in resources limited conditions, indicating the better performancer at acquiring and at using limited resources of E. adenophorum over its co-occurring native flora. Our study presented the distinctive advantages of E. adenophorum in resources-poor environments, indicating conventional strategy of managing resources levels to control the invasion and expending of exotic species may not be as effective as expected.

Effect of Spraying Liquorices Root Extract on Vegetative Growth, Chemical Characters and Photosynthetic Pigments of Chrysanthemum （Chrysanthemum morifolium L.） Grown under Salt Stress

This experiment was conducted in Horticulture Department, School of Plant Production, Faculty of Agriculture and Forestry, University of Duhok, Iraq in 2010 on Chrysanthemum plants, in order to mitigate the adverse influence of salinity by the use of liquorice root extract and study its effect on vegetative growth, chlorophyll content in leaves from chlorophyll and assistant pigment, carbohydrate and starch. Subsequently, the trail consisted of three levels of salinity （0, 4 and 8 ds m^-1） and three concentrations of the liquorice root extract 0, 2.5 and 5 g L^-1. Results showed that salinity （4 ds m^-1） rate caused significant increases in certain vegetative characteristics （branches number, plant height, leaves number and leaf area）, photosynthetic pigments （Chl a, Chl b, total chlorophyll, a-carotene, β-carotene, zeaxanthin, astaxanthin）, fresh shoot weight, fresh root weight, shoot dry weight, root dry weight, shoot： root ratio, carbohydrate dry weight percentage and starch percentage as compared to untreated check. However, increasing salinity rate to 8 ds m^-1 resulted in substantial reductions in all above mentioned Waits. Treatment with liquorices root extract, in particular, 5 g L^-1 manifested a potent capability in ameliorating the salinity negative effects in terms of vegetative and photosynthetic pigments aspects.

胡晗华、饶志明等获本刊优秀论文奖

根据我部决定(见本刊1999年第2期第159页)和有关专家推选评定，胡晗华、石岩峻、丛威、蔡昭铃的论文《不同氮磷水平下中肋骨条藻对营养盐的吸收及光合特性》[2004，10(6)：735～739]和饯志明、赵有玺、李辉、王正祥、沈微、方惠英、诸葛健的论文《太湖流域土壤微生物基因组总DNA分离纯化及其质粒文库的初步构建》[2004，10(6)：774～777]获本刊2004年第5期优秀论文奖。

加强果树后期管理 确保果树连年丰收

果实成熟至落叶前,营养生长渐趋停止,叶片内的光合营养物质却源源不断地输送到根、枝干木质部及髓等器官中贮存起来,直至入冬叶片脱落后进入休眠.实践证明这一时期果树管理的好坏,直接影响甚至决定当年花芽分化质量和树体营养积累水平,以及树体越冬能力和翌年萌芽生长状况.因此,加强果树采果后的管理是非常重要的.

Ecophysiological responses of two poplar species to intraspecific and interspecific competition under different nitrogen levels

Aims Populus deltoides and P.euramericana are widely used in China as major forestry species.At present,little is known about their responses to nitrogen(N)deficiency when grown in monocultures or mixed plantations.The aim of this investigation was to analyze the growth,and morphological and physiological responses of P.deltoides and P.euramericana to different N levels under competition conditions.Methods We employed two Populus species(P.deltoides and P.euramericana)to discover how N deficiency affects plant traits under different competition types(P.deltoides×P.deltoides,intraspecific competition;P.euramericana×P.euramericana,intraspecific competition;P.deltoides×P.euramericana,interspecific competition).Potted seedlings were exposed to two N levels(normal N,N deficiency),and nitrogen-and competition-driven differences in growth,morphology and physiology were examined.Important Findings Under normal N conditions,interspecific competition significantly decreased the total root weight,root mass fraction(RMF),root–shoot ratio(R/S)and carbon/nitrogen ratio(C/N),and increased the leaf dry weight,leaf mass fraction and total leaf area of P.euramericana compared with intraspecific competition.The same conditions significantly affected the growth and morphological variables of P.deltoides,except for the dry weight of fine roots,R/S,specific leaf area,RMF,total nitrogen content and C/N compared with intraspecific competition.In addition,chlorophyll a(Chla),total chlorophyll(Tchl),carotenoid contents(Caro)and the carbon isotope composition(δ13C)of P.deltoides were significantly lower in interspecific competition than in intraspecific competition,but no difference was detected in P.euramericana.The effects of N deficiency on P.deltoides under intraspecific competition were stronger than under interspecific competition.In contrast,the effects of N deficiency on P.euramericana between intraspecific and interspecific competition were not significantly different.These results suggest that under normal N condition,P.deltoides is expected to gain an advantage in monocultures rather than in mixtures with P.euramericana.Under N deficiency,the growth performance of P.euramericana was more stable than that of P.deltoides under both cultivation modes.