大气CO2浓度的升高、施氮及土壤水分对春小麦干物质积累和氮吸收的影响

Spring wheat (Thiticum aestivum L.cv.Dingxi No.8654) was treated with two concentrations of atmospheric CO2 (350 and 700 μmol mol^-1),two levels of soil moisture (well-watered and drought) and five rates of nitrogen fertilizer(0,50,100,150,and 200 mg kg^-1 soil) to study the atmospheric CO2 concentration effect on dry matter accumulation and N uptake of spring wheat.The effects of CO2 enrichment of the shoot and total mass depended largely on soil nitrogen level,and the shoot and total mass increased significantly in the moderate to high N treatments but did not increase significantly in the low N treatment.Enriched CO2 concentration did not increase more shoot and total mass in the drought treatment than in the well-watered treatment.Thus,elevated CO2 did not ameliorate the depressive effects of drought and nitrogen stress.In addition,root mass decreased slightly and root/shoot ratio decreased significantly due to CO2 enrichment in no N treatment under well-watered condition.Enriched CO2 decreased shoot N content and shoot and total N uptake;but it reduced root N content and uptake slightly.Shoot critical N concentration was lower for spring wheat grown at 700 μmol mol^-1 CO2 than at 350μmol mol^-1 CO2 in both well-watered and drought treatments. The critical N concentrations were 16 and 19 g kg^-1 for the well-watered treatment and drought treatment at elevated CO2 and 21 and 26 g kg^-1 at ambient CO2,respectively. The reductions in the movement of nutrients to the plant roots through mass flow due to the enhancement in WUE (water use efficiency) and the increase in N use efficiency at elevated CO2 could elucidate the reduction of shoot and root N concentrations.     

在盐水浇灌条件下堆肥对土壤性质、小麦生长以及作物营养的影响

A greenhouse experiment was conducted to test and compare the suitability of saline compost and saline irrigation water for nutrient status amendment of a slightly productive sandy clay loam soil,to study the macronutrient utilization and dry matter production of wheat(Triticum aestivum c.v.Gemmiza 7) grown in a modified soil environment and to determine the effects of compost and saline irrigation water on soil productivity.The sandy clay loam soil was treated with compost of five rates(0,24,36,48,and 60 m 3 ha-1,equivalent to 0,3,4.5,and 6 g kg-1 soil,respectively) and irrigation water of four salinity levels(0.50(tap water),4.9,6.3,and 8.7 dS m-1).The results indicated that at harvest,the electrical conductivity(EC) of the soil was significantly(P < 0.05) changed by the compost application as compared to the control.In general,the soil salinity significantly increased with increasing application rates of compost.Soluble salts,K,Cl,HCO 3,Na,Ca,and Mg,were significantly increased by the compost treatment.Soil sodium adsorption ratio(SAR) was significantly affected by the salinity levels of the irrigation water,and showed a slight response to the compost application.The soil organic carbon content was also significantly(P < 0.05) affected by application of compost,with a maximum value of 31.03 g kg-1 recorded at the compost rate of 60 m 3 ha-1 and the irrigation water salinity level of 8.7 dS m-1 and a minimum value of 12.05 g kg 1 observed in the control.The compost application produced remarkable increases in wheat shoot dry matter production.The maximum dry matter production(75.11 g pot-1) occurred with 60 m 3 ha-1 compost and normal irrigation water,with a minimum of 19.83 g pot-1 with no addition of compost and irrigation water at a salinity level of 8.70 dS m-1.Significant increases in wheat shoot contents of K,N,P,Na,and Cl were observed with addition of compost.The relatively high shoot N values may be attributed to increases in N availability in the tested soil caused by the compost application.Similarly,significant increases in the shoot contents of Na and Cl may be ascribed to the increase in soil soluble K and Cl.The increases in shoot P,N,and K contributed to the growth stimulation since P supplied by the compost was probably responsible in saline and alkaline soils where P solubility was very low.     

水稻耐盐性的机理

Shaheen Basmati was evolved as a salt tolerant fine rice variety by the Soil Salinity Research Institute,Pindi Bhattian, Pakistan. Water culture studies were conducted to investigate the physiological mechanism exercised by this variety in particular and rice plant in general to face the saline environment. Performance of this rice variety and the concentration and uptake of ions were studied under stress of three salinity levels(30, 60 and 90 mmolL^-1) created with NaC1. Recorded data indicated that shoot dry matter was not significantly affected by all the three levels of salinity. However, NaC1 levels of 60 and 90 mmol L^-1 affected the root dry matter significantly. Sodium concentration and uptake was enhanced significantly in root and shoot at the first level of salinity (30 mmol L^-1) but thereafter the differences were non-significant, indicating the preferential absorption of this cation. The K concentration decreased significantly in shoots at all the levels. The impact was less pronounced in roots as far as K absorption was concerned. The effect on Ca and Mg concentrations was not significant. The values of K:Na, Ca:Na and (Ca Mg):Na ratios in shoot and root were comparatively low under stress conditions, indicating that selective ion absorption may be the principal salt tolerance mechanism of variety Shaheen Basmati when grown in a saline medium.     

丛枝菌根真菌Glomus mosseae 提高超氧化物歧化酶和过氧化氢酶活性和真盐生植物盐地碱蓬耐盐性

Arbuscular mycorrhizal (AM)-mediated plant physiological activities could contribute to plant salt tolerance. However, the biochemical mechanism by which AM fungi enhance salt tolerance of halophytic plants is unclear. A pot experiment was conducted to determine whether salt tolerance of the C 3 halophyte Suaeda salsa was enhanced by the AM fungus Glomus mosseae. When 60-day-old S. salsa seedlings were subjected to 400 mmol L-1 NaCl stress for 35 days, plant height, number of leaves and branches, shoot and root biomass, and root length of G. mosseae-colonized seedlings were significantly greater than those of the nonmycorrizal seedlings. Leaf superoxide dismutase (SOD) activity at all sampling times (weekly for 35 days after salt stress was initiated) and leaf catalase (CAT) activity at 2 and 3 weeks after salt stress was initiated were also significantly enhanced in G. mosseae-colonized S. salsa seedlings, while the content of leaf malondialdehyde (MDA), a product of membrane lipid peroxidation, was significantly reduced, indicating an alleviation of oxidative damage. The corresponding leaf isoenzymes of SOD (Fe-SOD, Cu/Zn-SOD1, and Cu/Zn-SOD2) and CAT (CAT1 and CAT2) were also significantly increased in the mycorrhizal seedlings after 14 days of 400 mmol L-1 NaCl stress. Our results suggested that G. mosseae increased salt tolerance by increasing SOD and CAT activities and forming SOD and CAT isoforms in S. salsa seedlings.     

不同磷水平下玉米和小麦植株亚细胞中镉的积累

Corn and wheat plants were grown in a nutrient culture solution at four levels of phosphorus (0,0.12,0.60 and 3.0mmol L^-1) and two levels of cadmium(0 and 4.0umol L^-1) in greenhouse for a 18-day period.The concentrations of phosphorus and cadmium in cell wall,cytoplasm and vacuoles of roots and leaves were examined by cell fractionation techniques.With increasing phosphorus in medium,the contents of P in cell wall,cytoplasm and vacuoles of corn and wheat roots and leaves increased.The highest content of P was observed in cell wall,next in vacuoles,and the lowest in cytoplasm.The wheat subcellular fractions in both roots and leaves hab higher concentrations of phosphorus than those of corn.Increasing phosphorus in medium significantly inhibited the intracellular Cd accumulation in both species,However,at P concentration up to 3.0mmol L^-1,the Cd content in cell wall was increased.Increasing phosphorus resulted in reduction of the subcellular Cd content in cell wall was increased.Increasing phosphorus resulted in reduction of the subcellualr Cd content in corn and wheat leaves.Compared with corn,the wheat roots had a higher Cd content in the cell wall and vacuoles and a lower in cytoplasm,while in leaf subcellular fractions the wheat cell had a higher Cd content in its vacuoles and a lower one in its cytoplasm,The results indicate that phosphorus may be involved in sequestration of Cd ionic activity in both cell wall and vaculoes by forming insoluble Cd phosphate.     

油菜光合生产模拟模型

Photosynthetic production is a major determinant of final yield in crop plants. A simulation model was developed for canopy photosynthesis and dry matter accumulation in oilseed rape (Brassica napus L.) based on the ecophysiological processes and using a three-layer radiation balance scheme for calculating the radiation interception and absorption by the layers of flowers, pods, and leaves within the canopy. Gaussian integration method was used to calculate photosynthesis of the pod and leaf layers, and the daily total canopy photosynthesis was determined by the sum of photosynthesis from the two layers of green organs. The effects of physiological age, temperature, nitrogen, and water deficit on maximum photosynthetic rate were quantified. Maintenance and growth respiration were estimated to determine net photosynthetic production. Partition index of the shoot in relation to physiological development time was used to calculate shoot dry matter from plant biomass and shoot biomass loss because of freezing was quantified by temperature effectiveness. Testing of the model for dynamic dry matter accumulation through field experiments of different genotypes, sowing dates, and nitrogen levels showed good fit between the observed and simulated data, with an average root mean square error of 10.9% for shoot dry matter. Thus, the present model appears to be reliable for the prediction of photosynthetic production in oilseed rape.     

水培条件下加入钾和硅减轻甘蔗盐胁迫效应

A hydroponics experiment was conducted to evaluate the role of potassium (K) and silicon (Si) in mitigating the deleterious effects of NaCl on sugarcane genotypes differing in salt tolerance. Two salt-sensitive (CPF 243 and SPF 213) and two salt-tolerant (HSF 240 and CP 77-400) sugarcane genotypes were grown for six weeks in ? strength Johnson’s nutrient solution. The nutrient solution was salinized by two NaCl levels (0 and 100 mmol L-1 NaCl) and supplied with two levels of K (0 and 3 mmol L-1) and Si (0 and 2 mmol L-1). Applied NaCl enhanced Na+ concentration in plant tissues and significantly (P ≤ 0.05) reduced shoot and root dry matter in four sugarcane genotypes. However, the magnitude of reduction was much greater in salt-sensitive genotypes than salt-tolerant genotypes. The salts interfered with the absorption of K+ and Ca2+ and significantly (P ≤ 0.05) decreased their uptake in sugarcane genotypes. Addition of K and Si either alone or in combination significantly (P ≤ 0.05) inhibited the uptake and transport of Na+ from roots to shoots and improved dry matter yields under NaCl conditions. Potassium uptake, K+/Na+ ratios, and Ca2+ and Si uptake were also significantly (P ≤ 0.05) increased by the addition of K and/or Si to the root medium. In this study, K and Si-enhanced salt tolerance in sugarcane genotypes was ascribed to decreased Na+ concentration and increased K+ with a resultant improvement in K+/Na+ ratio, which is a good indicator to assess plant tolerance to salt stress. However, further verification of these results is warranted under field conditions.     

高钾供应加剧了水稻叶片缺镁诱导的氧化胁迫

Magnesium （Mg） deficiency in plant affects photosynthesis and many other metabolic processes. Rice （Oryza sativa L. cv. ＇Wuyunjing 7＇） plants were grown in hydroponics culture at three Mg and two potassium （K） levels under greenhouse conditions to examine the induction of oxidative stress and consequent antioxidant responses in rice leaves due to Mg deficiency. At low Mg （0.2 mmol L 1 Mg supply for two weeks after transplanting） and high K （6 mmol L^-1） for 21 days, the rice plants showed severe Mg deficiency and a significant decreases in the dry matter production. The Mg deficiency in leaves decreased chlorophyll concentrations, photosynthetic activity, and soluble protein, but significantly increased the concentrations of soluble sugars and malondialdchyde （MDA） and the activities of superoxide dismutase （SOLD, EC 1.15.1.1）, catalase （CAT, EC 1.11.1.6） and peroxidase （POD, EC 1.11.1.7）. In addition, Mg concentrations in the leaves and in the shoot biomass were negatively related to the activities of the three antioxidative enzymes and the concentration of MDA in leaves. There were very significant interactive effects between Mg and K supplied in the culture solution on shoot biomass yield, chlorophyll content, photosynthesis rate, the activities of SOD, CAT and POD, and MDA content in the leaves of rice. It is suggested that the high K level in the nutrient solution aggravated the effect of low Mg supply-induced Mg deficiency and created the oxidative damage in rice plants.     

表施尿素的冬小麦土壤氨挥发损失

Ammonia volatilization was measured with a continuous air flow enclosure method from a winter wheat field in the Experimental Farm of Jurong Agricultural School to investigate its main influencing factors. The experiment with five treatments in triplicate, no N (control), 100, 200 and 300 kg N ha^-1 with rice straw cover at a rate of 1 500 kg ha^-1 and 200 kg N ha^-1 without rice straw, started when the winter wheat was sown in 1994. Sixty percent of the total amount of N applied was basal and 40% was top-dressed. The measurement of ammonia volatilization was immediately conducted after urea was top-dressed on soil surface at wheat elongation stage in spring of 1996 and 1997. The results showed that there was a diurnal variation of ammonia volatilization rate from the winter wheat field, which synchronized with air temperature. N losses through ammonia volatilization increased with increasing N application rate, but the ratio of N lost through ammonia volatilization to applied N was not significantly affected by N application rate. The coverage of rice straw had no significant effect on ammonia volatilization. Soil moisture and rain events after urea was top-dressed affected ammonia volatilization significantly.     

施用磷和锌对植株体中锌营养及代谢的影响

A solution culture experiment was conducted to investigate the growth,the accumulation and translocation of Zn,and the metabolic changes of 24 days old plants of corn and wheat with the varied suply of phosphorus(0,0.12,0.6 and 3.0mmol L^-1)and zinc (0.1 and 2.0umol L^-1) under controlled environmental conditions.The results showed the highest dry matter production of both corn and wheat under the moder ate combination of phosphorus(0.6mmol L^-1) and zinc(2.0 umolL^-1) as compared with other imbalance applications of phosphorus and zinc.Excessive P supply significantly inhibited the translocation of Zn from roots of corn to the aboveground part,thus decreasing the content of Zn in the shoots.Application of 3.0 mmolL^-1 P could also reduce the water-soluble Zn in plant tissues,leading to an increase in the cell plasma membrane permeability,a decrease in the dehydrogenase activity in roots and the activity of nitrate reductase in leaves,and a decline in the uptake of nitrate by plants.A similar decrease occurred in superoxide dismutase(SOD) and plasma membrane adenosine triphosphatase(ATPase)activity in Zn-deficient plants.But,with increasing P supply the activity of ATP ase in both corn and wheat increased and reached the maximum at the P-supplying level of 3.0 mmolL^-1.Similar to the effect of high P supply.no or low P(0.12mmolL^-1) supply could be detrimental to dry matter production and physiological functioning of the plants.Corn plants showed a more significant response to the imbalance supply of P and Zn than wheat plants.The possible physiological and biochemical mechanism of phosphorus-zinc antagonistic interaction in corn and wheat might be attributed to decrease in physiological availability and activation of Zn.     

中国西北地区膜下滴灌对棉田土壤CO2通量和浓度的影响

In northwestern China,there has been a change from traditional cultivation system (TC) with no mulching and flood irrigation to a more modern cultivation system (MC) using plastic film mulching with drip irrigation.A field study was conducted to compare soil CO 2 concentrations and soil surface CO 2 fluxes between TC and MC systems during a cotton growing season.CO 2 concentrations in the soil profile were higher in the MC system (3 107-9 212 μL L-1) than in the TC system (1 275-8 994 μL L-1) but the rate of CO 2 flux was lower in the MC system.Possible reasons for this included decreased gas diffusion and higher soil moisture due to the mulching cover in the MC system,and the consumption of soil CO2 by weathering reactions.Over the whole cotton growing season,accumulated rates of CO2 flux were 300 and 394 g C m-2 for the MC and TC systems,respectively.When agricultural practices were converted from traditional cultivation to a plastic film mulching system,soil CO 2 emissions could be reduced by approximately 100 g C m-2 year-1 in agricultural lands in arid and/or semi-arid areas of northern and northwestern China.     

Wheat Growth and Photosynthesis as Affected by Oxytetracycline as a Soil Contaminant

Extensive worldwide use of oxytetracycline (OTC),a member of the tetracyclines,has resulted in its accumulation in soils,posing a potential risk to food production and safety.A pair of OTC-sensitive (Heyou 1) and OTC-tolerant (Yannong 21) wheat (Triticum aestivum L.) cultivars was compared hydroponically at 0.01,0.02,0.04,and 0.08 mmol L-1 OTC in terms of wheat growth and photosynthesis.Biomass and shoot length decreased significantly with the addition of OTC,with the decreases in dry biomass and shoot leng...     

外施氯对油菜幼苗生长和光合特征影响的研究

采用盆栽砂培试验,研究了不同浓度氯离子（Cl-）处理对油菜（Brassica napus L.）幼苗干物质积累速率（DMAR）、根冠比（R/S）、叶绿素（Chl）含量、氯离子含量（Cl-）、净光合速率（Pn）、气孔导度（Gs）、细胞间CO2浓度（Ci）、蒸腾速率（Tr）、水分利用效率（WUE）、气孔限制值（Ls）等的影响。结果表明:25～100 mmol/L Cl- 处理9 d和18 d,油菜幼苗植株DMAR均上升,均在50 mmol/L Cl- 处理时达到最大值;不同浓度Cl- 处理9 d,Chl含量有先上升后下降的趋势,在100 mmol/L Cl- 处理时达到最大值,处理18 d,Chl含量依次下降。Cl- 处理能显著提高叶片中的Cl- 含量。除了在处理18 d后的Ci外,25～100 mmol/L Cl- 处理下,油菜叶片均能维持较高的Pn、Gs、Ci和Tr,200 mmol/L Cl- 处理9 d和18 d,油菜叶片Pn、Gs、Ci和Tr均显著下降。随着Cl- 浓度的增加,WUE呈现先降后升,在9 d处理后,随着Cl- 浓度的增加,油菜Ls也呈现先升后降,而在18 d处理后,随着Cl- 浓度的增加,Ls逐渐显著上升。上述结果表明,外施低量氯（Cl- 25~100 mmol/L）显著提高或者维持油菜幼苗的光合作用和蒸腾作用,促进油菜幼苗的生长;而高氯（200 mmol/L Cl-）条件下显著降低其光合作用和蒸腾作用,抑制其生长,且抑制油菜幼苗光合的主要是气孔因素。相关性分析还表明,植株DMAR、Pn、Ci、Tr、Gs之间均有显著的正相关性,而Pn与WUE之间存在极显著的负相关。     

不同间作模式下木薯花生光合效率比较

田间设置木薯和花生的不同间作措施处理,利用LI-6400光合仪测定不同处理的光合日变化。结果表明:①木薯、花生的生长环境因子的日变化均为"单峰"型曲线,其中光合有效辐射（PAR）、田间CO₂浓度（Ca）呈开口向下曲线,大气相对湿度（RH）、大气温度（Ta）的日变化曲线则开口向上。②不同间作措施中,间作窄行并无绝对优势;间作宽行可保证作物产量,但其瞬时水分利用效率（WUE）和气孔限制值（Ls）均最低,不利于在缺水环境下推广;间作双行的WUE和CO₂利用效率最高,这在严重水分胁迫条件无疑是最优选择。③由统计分析可知,对花生和木薯净光合速率（Pn）影响显著的因子均为作物蒸腾速率（Tr）、胞间CO₂浓度（Ci）、气孔导度（Cond）和气孔限制值（Ls）,其中Pn与Tr、Cond、Ls呈正相关,与Ci呈负相关。术薯、花生的"午休"现象主要由非气孔因素决定,其气孔机制是作物蒸腾速率（Tr）和胞间CO₂浓度（Ci）双重起作用的结果,首先起作用的是Tr诱发的光抑制,之后气孔开关则是由Ci调控。     

NaCl胁迫对甘薯叶片水分代谢、光合速率、ABA含量的影响

以耐盐品种徐薯 1 8、中等耐盐品种栗子香和不耐盐品种胜利百号为材料 ,用 1/2Hoagland营养液配制浓度为 0、85、170、255、340mmolL-1 的NaCl溶液分别胁迫 6d后进行指标分析。试验结果表明 ,随着NaCl胁迫浓度的提高 ,甘薯叶片水势 (w)、相对含水量 (RWC)逐渐下降 ,光合速率 (Pn)、蒸腾速率 (Tr)、水分利用率 (WUE)、气孔导度 (Gs)、气孔开度也明显下降 ;低浓度NaCl胁迫下胞间CO2 浓度 (Ci)下降 ,随着NaCl胁迫浓度的提高 ,Ci逐渐上升 ;脱落酸 (ABA)含量则随NaCl胁迫浓度的提高而上升。NaCl胁迫下上述指标在不同耐盐品种间存在明显差异 ,而且NaCl胁迫浓度与RWC、w、Pn、Tr、Gs呈极显著的负相关。在NaCl浓度为 85mmolL-1 以上时 ,NaCl浓度与Ci、ABA含量呈极显著的正相关 ;RWC、w与ABA间呈极显著负相关 ,与Pn、Tr、Gs之间呈极显著的正相关 ;ABA含量与Pn、Tr、Gs之间呈极显著的负相关。     

土壤水分胁迫对杜仲叶片光合及水分利用特征的影响

通过实验研究了华北石质山区4种不同土壤水分条件下3a生杜仲苗木叶片光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、胞间CO2浓度(Ci)、气孔限制值(Ls)、水分利用效率(WUE)等参数的光响应过程。结果表明:(1)杜仲叶片在土壤水分轻度(W1)、中度(W2)和重度(W3)胁迫条件下的光饱和点分别比对照(CK)下降12.5%、44.8%、68.5%,晴天日光合速率最大值分别比对照(CK)下降21.5%、47%、69.7%;(2)叶片蒸腾速率(Tr)呈现随光合有效辐射(PAR)增加而上升的趋势。对比CK,Tr在W1、W2和W3条件下分别下降了17%、52%和93%;(3)Gs随着PAR的增加而逐渐上升。对比CK,Gs在W1、W2和W3条件下分别下降了22.6%、67.9%、88.7%。从无水分胁迫一直到中度水分胁迫条件下,气孔限制是影响光合作用的主要原因,而土壤水分严重胁迫条件下,当PAR小于1000μmol.m-2.s-1时,气孔限制是影响光合作用的主要原因,尔后转变为非气孔限制;(4)叶片水分利用效率(WUE)对光强的适应范围比较广,W3条件下,WUE值最高。CK、W1、W2条件下,WUE相差不大,对比W3,分别下降68.6%、69.5%、67.3%。     

黄土高原侧柏、臭椿光合、蒸腾作用比较研究

对黄土高原半干旱区侧柏和臭椿的光合、蒸腾特性进行了系统的研究,并对光合速率、蒸腾速率、气孔导度、水分利用率和胞间CO₂浓度进行了分析,结果表明:臭椿的日蒸腾速率、日光合速率、水分利用效率和气孔导度均高于侧柏;臭椿和侧柏的胞间CO₂浓度都随着光合速率的变化而变化,光合速率高则胞间CO₂浓度较低,反之则较高,侧柏和臭椿在长期适应环境的过程中产生了不同的生理生态对策.     

桃光合性能杂种优势的秋季日变化特征

以桃品种“吊枝白”和“霞晖5 号”及其杂交F1 代种苗为试验材料, 研究了桃在秋季的光合性能杂种优势日变化特征。结果表明: 净光合速率(Pn)午间表现正向杂种优势, 蒸腾速率(Tr)和气孔导度(Gs)全天基本表现负向杂种优势, 而水分利用效率(WUE)则全天基本表现正向杂种优势。相关性分析表明, 杂交F₁ 代种苗的Pn 与Tr、Pn 与Gs、Tr 与Gs 均呈正相关, 其中Pn 与Tr 之间相关性达显著水平(P<0.05); 亲本的Pn 与Tr之间呈显著正相关(P<0.05), Gs 与Pn、WUE 之间呈显著正相关(P<0.05)。灰色关联度分析表明, 影响Pn、Tr和WUE 杂种优势率的主要因素均为大气CO₂ 浓度(Ca)。     

氮磷钾对春茶光合生理及氨基酸组分的影响

【目的】当前为追求茶园高产盲目施肥、滥用化肥造成生态环境破坏的现象较为严重,因此如何合理施肥显得尤为重要,本文通过研究氮、磷、钾不同水平及其配比对春茶净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、胞间CO2浓度(Ci)和水分利用效率(WUE)等光合生理指标和春茶新梢氮、磷、钾含量,氨基酸总量及其组分的影响,为茶园平衡施肥和精准施肥提供理论指导。【方法】采取单因素试验设计,设氮、磷、钾各3个水平及其配比和对照,共14个处理(N1、N2、N3、P1、P2、P3、K1、K2、K3、NP、NK、PK、NPK、CK),在茶树新梢长至1芽3叶时采样,用Li-6400便携式光合测定仪测定茶树的光合生理指标,用氨基酸自动分析仪测定春茶氨基酸总量及组分含量,分别采用凯氏定氮法、钒钼黄比色法和原子吸收分光光度法测定茶树新梢的全氮、全磷和全钾含量。分析不同施肥处理对茶树光合生理指标和春茶氨基酸总量及其组分的影响,并通过逐步回归分析建立Pn与茶树新梢氮、磷、钾含量,Tr、Gs和Ci的回归方程。【结果】NPK处理茶树Pn比CK提高9.70%;P2、P3和NPK处理的Tr显著增加,比CK分别提高10.60%、14.92%、14.25%;NPK处理的Gs显著增加,比CK高23.15%,同时Gs随不同施肥水平表现出与蒸腾速率较一致的趋势,二者的相关性极显著;Ci随氮、磷、钾施用量的增加而上升;WUE随氮、磷、钾施用量的增加而下降。NPK处理的茶树新梢的氮、磷含量较高,相同施肥处理的茶树新梢的磷含量低于氮、钾。逐步回归分析显示,茶树新梢磷含量,Ci和Gs对Pn的直接作用较大,直接通径系数分别为0.3688、-0.8139和0.4677,Pn=12.955+26.624P-0.087Ci+38.233Gs;NPK处理下春茶氨基酸总量及茶氨酸、天冬氨酸、苏氨酸、丝氨酸和胱氨酸等主要氨基酸组分的含量分别比对照提高了27.88%、26.60%、35.78%、35.06%、24.41%和24.41%,与对照差异显著。【结论】新梢磷含量和气孔导度对春茶净光合速率的提高有直接的促进作用,而胞间CO2浓度对净光合速率有一定的消减作用。氮磷钾配施可显著提升茶树新梢叶片的气孔导度并保证茶树新梢中较高的磷含量,从而提高了茶树的净光合速率。氮磷钾肥配施能显著提高春茶氨基酸总量及其组分含量,提高了春茶的品质,表明茶叶中氨基酸总量和茶氨酸等重要组分含量的提高是氮、磷、钾营养共同作用的结果。因此,氮磷钾配合施用可以提高春茶的产量和品质。     

土壤干旱条件下锰肥对夏玉米光合特性的影响

在盆栽条件下进行了土壤干旱时夏玉米施用微量元素锰的试验。通过测定拔节期玉米叶片气孔导度(Cs)、细胞间隙CO2浓度(Ci)、蒸腾速率(Tr)、光合速率(Pn)和水分利用效率(WUR)等指标,探讨了干旱胁迫下外源锰对夏玉米光合特性的影响。结果表明,施用锰肥能降低光合作用的气孔限制和非气孔限制,显著提高夏玉米光合能力。锰肥对夏玉米光合作用的影响在土壤干旱时尤为显著。土壤干旱情况下,锰肥可使玉米叶片Cs增加58.11%,Pn和WUR分别增加42.07%和50.00%,从而减轻了土壤干旱对玉米光合作用的抑制。