Differential effects of UV-B radiation fluence rates on growth,photosynthesis, and phosphate metabolism in two cyanobacteria under copper toxicity

This work was undertaken to ascertain the impact of different fluence rates of ultraviolet-B (UV-B) radiation on two cyanobacterial biofertilizers, Phormidium foveolarum and Nostoc muscorum, growing under copper toxicity. Copper (2 and 5?µmol?L^?1) and high UV-B fluence rate (UV-B_H; 1.0?µmol?m^?2?s^?1) decreased the growth, pigment content, photosynthetic oxygen yield, phosphate uptake, and acid phosphatase activity in both the strains analyzed after 24 and 72?h of experiments, and combined exposure further enhanced the toxic effects. Respiration and alkaline phosphatase activities were stimulated appreciably. The damaging effect was shown on the order on pigments: phycocyanin?>?chlorophyll a?>?carotenoids, and on photosystems: whole chain photosynthetic reaction?>?photosystem II?>?photosystem I. Partial recovery in the photosystem II activity in the presence of artificial electron donors; diphenyl carbazide (DPC), hydroxylamine (NH₂OH), and manganese chloride (MnCl₂) pointed out the interruption of electron flow on the oxidation side of photosystem II. Unlike UV-B_H, low UV-B fluence rate (UV-B_L; 0.1?µmol?m^?2?s^?1), rather than causing damaging effect partially, alleviated the toxic effects of Cu. This study suggests that the cyanobacterium P. foveolarum is less sensitive against UV-B_H and excess Cu (2 and 5?µmol?L^?1), thus P. foveolarum may be used as a biofertilizer for sustainable agriculture.     

UV-B辐射增强对冬小麦生长发育及产量的影响

研究了大田栽培条件下紫外辐射增强对冬小麦孕穗、抽穗、开花、灌浆、结实以及产量的影响。结果表明,UV B辐射增强使小麦植株矮化,叶面积减小,穗重、茎重、叶重减小,灌浆速度变慢,灌浆不充实,此外,UV B辐射增强还使花粉败育率增大。     

Sublethal impairment of respiratory control in plaice (Pleuronectes platessa) larvae induced by UV-B radiation, determined using a novel biocybernetical approach

The increasing amount of UV-B radiation (280 to 320 nm) reaching the earth's surface could endanger transparent fish and zooplankton in upper water layers. Previous studies on marine fish eggs and larvae focused mainly on the effects of high, lethal doses of ultraviolet irradiation. Now a sensitive test for accumulated, sublethal impairments of physiological performance has been established. In developing fish larvae (Pleuronectes platessa L.), the respiratory control responses to hypoxia were evaluated by combining a biocybernetical approach and a novel optical test system. Before testing respiratory control behavior, the larvae were irradiated with light containing UV-B (test individuals) or free from it (control individuals). Differences in the physiological reactions of these larvae were detected by biocybernetical analysis (linear systems analysis) of respiratory control. The analysis was based on the evaluation of changes in ventilatory rate caused by sinusoidally modulated partial pressures of ambient oxygen. The ventilatory movements of the larvae were recorded, analyzed and evaluated by video microscopy and digital image processing. After several days of irradiation with moderate UV-B doses or intensities (8.6 kJ m⁻² d⁻¹, corresponding to an irradiance of 0.24 W m⁻² for 10 h), sublethal impairments of respiratory control could be detected in plaice larvae by this method; both the linearity of respiratory control itself and the parameters of linear control behavior were affected by UV-B. Concerning environmental implications, the results must still be interpreted cautiously, because natural irradiation conditions are more complex than the artificial regimen. Our biocybernetical approach will be useful for further studies on sublethal impairments of physiological functions caused by UV-B in fish and other transparent marine or limnic animal groups. In addition, the method could be used to test the sublethal impact of chemical contaminants. Received: 4 November 1997 / Accepted: 6 May 1998     

Reproduction and growth of Euterpina acutifrons (Copepoda: Harpacticoida) under experimental conditions

Individual specimens of Euterpina acutifrons (Copepoda: Harpacticoida) taken from the mass cultures of the C.N.E.N.-EURATOM Laboratory at Fiascherino, Italy, were reared in new culture media prepared with suspensions of several species of algae in filtered and sterilized sea water. All the experiments were carried out at a temperature of 18°C±1 C°. The influence of food concentrations on adult life-span and reproductive activity of E. acutifrons was analyzed. A good correlation was found between concentration of algal suspension and egg production. Maximum life-span was observed at intermediate values of food concentration. Other experiments were carried out to determine egg fertility and duration of the various embryonic and postembryonic development stages. Embryonic development time was calculated as approximately 2 days; the adult females appeared 10 to 12 days after hatching of Nauplius I. Production of nauplii by 6 females reared under conditions of excess food supply was also studied. These conditions were achieved by supplying high concentrations of a mixture of 4 different algal species and by completely renewing the culture medium at frequent intervals. Under these conditions, each female laid an average of 12.5 sacs and produced an average of 294.3 nauplii. An average production of 355.5 eggs per female was estimated. An analysis was made of growth in size and weight of the females: the average daily egg production in terms of dry weight corresponded to about 32% of the biomass of the adult female. Birch's (1948) method was used to calculate net reproduction rate (R _o=70.89), intrinsic rate of increase (r _m=0.161) and mean generation time (T=26.5 days).This study was performed at: Laboratorio per lo Studio della Contaminazione Radioattiva del Mare, C.N.E.N.-EURATOM, Fiascherino, I-19030 La Spezia, Italy.     

Harvest time residues of pendimethalin in tomato,cauliflower, and radish under field conditions

Herbicides applied to vegetables play an important role in higher production of vegetables due to effective and timely control of weeds but at the same time herbicides residue may produce numerous environmental problems. The aim of this study was to determine whether application of herbicide for control of annual weeds in vegetable growing areas at recommended levels resulted in residues at the time of harvest. Thus, terminal residues of pendimethalin in vegetables such as tomato, cauliflower, and radishes were studies under field conditions. Pendimethalin was applied as pre-emergence herbicides at 1 kg a.i. ha^?1 to tomato, cauliflower, and radish crops. Soil and vegetables samples were collected from pendimethalin-treated plots at maturity to determine harvest time residues of pendimethalin. At harvest, 0.008, 0.001, and 0.014 μg/g residues of pendimethalin were found in tomato, cauliflower, and radishes, respectively.     

Sexual signalling and viability in a wolf spider (Hygrolycosa rubrofasciata): measurements under laboratory and field conditions

This study examined the crucial prediction of the conditional-handicap theory, the relationship between male sexual trait size and male viability, in the wolf spider Hygrolycosa rubrofasciata. In this species, males court females by drumming dry leaves with their abdomen, and males with the highest drumming rate enjoy highest mating success. We determined male drumming rate, body mass, and mobility, which reflects mate-searching activity, in relation to male survival. Because it is often difficult to know how results obtained from laboratory studies reflect the natural world, particularly when the measured variable is survival, we repeated our study in both laboratory and field conditions. Males drumming at the highest rate survived better than males drumming at a lower rate in both laboratory and field conditions. These results are in accordance with the predictions of conditional-handicap models of sexual selection. Survival was independent of male body mass and there was no significant correlation between male drumming activity and body mass. However, large males moved further than smaller males, and males moving longer distances lost less mass than those moving shorter distances. These results suggest that, moving, and consequently mate-searching activity, may be a condition-dependent trait and that there may be a advantage for large males in mate searching. Received: 22 October 1998 / Received in revised form: 28 January 1999 / Accepted: 14 February 1999     

Photosynthetic and growth responses of Japanese sasabamo (Potamogeton wrightii Morong) under different photoperiods and nutrient conditions

Controlled laboratory experiments were conducted to examine how photosynthesis and growth occur in Potamogeton wrightii Morong under different photoperiods and nutrient conditions. The experiment was based on a 3×2 factorial design with three photoperiods (16, 12 and 8 h) of 200 μE · m^?2·s^?1 irradiance and two nutrient conditions, high (90 μmol N · L^?1·d^?1 and 9 μmol P · L^?1·d^?1) and low (30 μmol N L^?1·d^?1 and 3 μmol P · L^?1·d^?1). After 14, 28, 56 and 70 days of growth, plants were harvested to determine net photosynthesis rate and various growth parameters. Above- and below-ground biomass were investigated on days 56 and 70 only. Plants under low nutrient conditions had greater leaf area, more chlorophyll a, a higher rate of net photosynthesis and accumulated more above- and below-ground biomass than plants in the high nutrient condition. Plants with an 8 h photoperiod in the low nutrient condition had a significantly higher rate of net photosynthesis, whereas 8 h photoperiod plants in the high nutrient condition had a lower rate of net photosynthesis and their photosynthetic capacity collapsed on day 70. We conclude that P. wrightii has the photosynthetic plasticity to overcome the effects of a shorter photoperiod under a tolerable nutrient state.     

Maturation,epitoky and regeneration in the polychaete Eunice siciliensis under field and laboratory conditions

In the gonochoric polychaetous annelid Eunice siciliensis Grube, germ cells only develop in the posterior segments of the worm; these segments subsequently differentiate into an epitokous portion separating at maturity from the infertile body part. As in the Pacific and Atlantic palolo worms, the epitokous portions die some hours after spawning. Laboratory investigations revealed that the anterior parts of spawned worms survive and regenerate genital segments. After a period of at least 8 months, paired gonads are developed in these segments. Gonia proliferating later from the germinal tissue are released from gonadal sacs into the coelomal cavities, where gamete development occurs. A reproductive epitokous portion does not mature and separate until the second year of cultivation; it is followed by caudal regeneration. These facts and the observation that only about 50% of the individuals obtained from samples of coralligène were sexually differentiated, led to the conclusion that E. siciliensis probably has a bi-annual reproductive cycle. Caudal regeneration does not depend on the presence of a prostomia hormone. The ability to form posterior regenerates is inherent to the parapodial segments of all body regions, except for mature genital segments. This is also valid for the formation of morphologically different secondary prostomia. However, for initiation and further promotion of gametogenesis and epitokous development, at least one gonadotropic factor originating from the prostomium is required. Neurosecretory cells within the brain suggest this factor(s) to be of neuro-endocrine nature. Specimens developing secondary prostomia were found both under field and laboratory conditions. In several cases, sexual development took place, and even epitokous portions were separated from such individuals. From this it appears that the gonadotropic functions are re-established by the regenerated prostomia in order to ensure reproduction in individuals accidentally deprived of the anterior end. The possible rôle of temperature and light as environmental factors involved in the control of normal and regenerative growth, of sexual development and reproduction is discussed.     

Carbofuran induced changes in breeding of a freshwater fish,Labeo rohita (Hamilton)

The effect of carbofuran, a carbamate pesticide, on the breeding performance of the freshwater fish Labeo rohita (Hamilton) has been investigated in the present study. Breeding of L. rohita was conducted after treatment with three sublethal concentrations, i.e. 0.06, 0.15 and 0.30 mg L^?1 of carbofuran for 96 h. The present investigation showed that the number of total eggs and total amount of eggs (litre per kg body weight) decreased significantly (p < 0.01) at all concentrations of carbofuran in comparison to controls, while the reduction in fertilization percentage at all concentrations of carbofuran was not significantly different from controls. The reduction in hatching percentage, the expected number of hatchlings, and the expected number of hatched larvae were significantly (p < 0.01) different between treated and control groups at all carbofuran concentrations. No significant differences for the 96 h survivability of hatched larvae were reported at all concentrations of carbofuran.     

Endosulfan induced changes in phospholipids in the freshwater female catfish, Heteropneustes fossilis (Bloch)

The catfish, H. fossilis were exposed to endosulfan for 30 days at sub-lethal concentration (0.002 ppm) during different phases of its annual reproductive cycle. Its impact on total (TP) and different phospholipids- phosphatidylcholine (PC), phosphatidylserine (PS), phosphatdylinositol (Pl) and phosphatidylethanolamine (PE) were measured in liver plasma and ovary. On pesticide exposure, during preparatory phase, the hepatic TP PC and PE were declined. The plasma levels of TP, PC and PS were declined with the elevation of PE whereas in ovary only PC was lowered after endosulfan exposure. During pre-spawning phase, the hepatic TP, PC and PE declined in liver plasma and ovary after endosulfan exposure. During spawning phase, only plasma and ovarian phospholipids showed decrease in their levels following endosulfan exposure. In the post-spawning phase, endosulfan elevated the levels of TP, PC and PS in ovary but had no effect on their levels in liver and plasma. During resting phase, the TP, PC and Pl were found to be decreasing its levels. Thus it appears that this pesticide interfere with phospholipids metabolism during annual reproductive cycle of this species.     

Effect of temperature on the molting,growth and maturation of the antarctic krill Euphausia superba (Crustacea: Euphausiacea) under laboratory conditions

The effect of temperature on molting, growth, and maturation rates was studied on laboratory-maintained Euphausia superba. The length of intermolt periods (IMP's) was inversely proportional to temperature (20.10 d, SD=1.60, at 0.12°C; 16.87 d, SD=1.68, at 0.97°C; and 12.48 d, SD=0.90, at 4.48°C), and directly proportional to krill size at 0.12°C and 0.97°C. For individually maintained krill the maximum growth rate at 4.48°C (0.068 mm d^-1) was nearly twice that at 0.68°C (0.037 mm d^-1). There was no observable temperature effect on maturation rates. The maturation changes of juveniles at all temperatures indicated that more than two years are probably required to reach maturity. Mature males and females regressed to immature forms, suggesting that E. superba may reproduce in successive years. These results and previously reported field and laboratory data for E. superba and other euphausiid species suggest a 4+ year life span for this species.This work was supported by NSF grant DPP 76-23437     

Comparison of somatic growth and otolith increment growth in laboratory-reared larvae of Pacific saury, Cololabis saira, under different temperature conditions

The relationship between somatic growth and incremental growth of otoliths of Pacific saury, Cololabis saira (Brevoort), larvae under different temperature conditions was studied in the laboratory for three age groups (0 to 9, 10 to 20 and 20 to 30 d posthatch). Larvae were incubated from hatching to 9 d at 24, 20, and 16 °C. Further, larvae initially reared at an ambient temperature of 21.7 °C were transferred to experimental temperatures of 22, 18, and 14 °C on Day 10 and reared to Day 20 and similarly from Day 20 and reared to Day 30 posthatch. Growth trajectories of larvae sampled at the end of the three experiments were back-calculated using the biological intercept method and compared to the measured values 0 and 5 d after the start of each experiment. Back-calculated knob length at the different temperatures indicated no significant difference to the measured knob lengths except for the cases at 20 °C from hatching to 9-d-old larvae and at 14 °C from 20- to 30-d-old larvae. The close correlation between somatic and otolith growth shown in this study indicated the feasibility of estimating the growth history of Pacific saury larvae using otolith readings. Received: 14 April 1999 / Accepted: 27 October 1999     

Growth and reproduction of Pycnogonum litorale (Pycnogonida) under laboratory conditions

The complete life cycle of Pycnogonum litorale Ström was observed under laboratory conditions. At 15?°C and a 16?h light:8?h dark photocycle, the duration of embryonic development from oviposition to egg-hatching varied from 32 to 111?d. The onset of egg hatching ranged from 32 to 81?d after oviposition in different egg batches, and the period between the first and the last hatch within a single egg batch varied between 16 and 57?d. The larval period, consisting of five larval instars, lasted between 66 and 113?d. Juvenile development required seven (exceptionally 8 or 9) moults and lasted between 263 and 400?d. The average interval between successive moults in juveniles increased with increasing size from 24 to 82?d. Though females did not moult more often than their male conspecifics, they reached a size from 8.5 to 11.0?mm (average 10.1?mm) while adult males measured only 7.0 to 8.5?mm (average 7.7?mm). At low temperatures (2?°C) moulting was almost completely inhibited. After raising the temperature to 6?°C, the moulting frequency increased to a rate almost as high as at a constant temperature of 15?°C. Moulting was also retarded by starvation and accelerated by subsequent feeding. Adults lived for up to 9?years without further moults, with several periods of mating and oviposition at irregular intervals. In combination with previous long-term field observations, the present results provide a more complete picture of the life cycle of P. litorale in a natural habitat. The great variation in the duration of the different developmental stages, the ability to survive periods of cold and starvation, and the longevity of the adults are important for the survival of pycnogonid populations under changing environmental conditions.     

Diurnal photosynthesis, water use efficiency and light use efficiency of wheat under Mediterranean field conditions

Photosynthesis and transpiration rates of wheat leaves (Triticum aestivum L.) were measured at 30 min intervals under Mediterranean field conditions, using Photosynthesis Monitor system (PM-48M). The dynamics of net photosynthetic rate (P(N)), transpiration rate (E(T)), water use efficiency (WUE), light use efficiency (LUE), stomatal conductance (g(s)), photosynthetically active radiation (PAR), air temperature (T), relative humidity (RH), and atmospheric CO2 concentration (Catm) were quantified at five rainfed wheat sites with the same stages of development (midflowering) along south-to-north and east-to-west transects for eight days in April. Diurnal P(N) (3.6 to 6.6 micromol m(-2) s(-1)), PAR (392 to 564 micromol m2 sec(-1)), LUE (0.006 to 0.015) and WUE (0.0001 to 0.011) did not vary significantly across all five wheat sites (p > 0.05). P(N) and E(T) were strongly coupled and highly correlated with PAR (p < 0.001). Best multiple linear regression (MLR) models accounted for 92% of variations in P(N) as a function of PAR and E(T), and 90% in E(T) as a function of PAR and RH (p < 0.001). P(N) exhibited a peak at mid-morning, and a photosynthetic midday depression under the limiting effects of high evaporative demand. Diurnal variations in WUE and LUE showed a bimodal behavior with the maximum values in early morning and late afternoon. As the impacts of global climate change become increasingly felt, continuous measurements of climate-crop-soil-managementinteractions under natural conditions play a pivotal role not only in exploring changes in ecophysiological properties of strategic crops for food security such as wheat but also in devising preventive and mitigative management practices to ensure sustained agricultural productivity.     

Utilization of growth parameters of eelgrass,Zostera marina,for productivity estimation under laboratory and in situ conditions

Allometry was used for monitoring aboveground growth of the marine angiosperm Zostera marina L. Dry weight was regressed with leaf length and width, allowing estimation of aboveground net productivity and biomass of individual plants. At the termination of the experiment, rhizome productivity of the same plants was determined by harvesting. Plants in shaded and unshaded seawater tanks were monitored from June until September, 1976; in situ plants were also monitored at Point Judith Pond, Rhode Island, USA. Unshaded plants had shorter leaves, a lower net productivity, lower biomass, and a lower aboveground-torhizome productivity ratio than shaded plants. Unshaded plants had a higher rate of rhizome branching and the resulting new shoot formation than in situ plants.     

海洋硅藻三角褐指藻经黑暗与UV辐射后的补偿生长(英文)

补偿生长是生物体对环境变化的一种适应性反应,主要指生物体遭受到不良环境胁迫后其生长及生理机能受到制约,但当不良环境胁迫解除后,生物体的生长能力会得到不同程度的恢复,表现出相对未受不良环境胁迫生物体超常生长的现象.迄今为止,补偿生长研究的对象主要集中在水生动物、反刍动物和高等植物上,而针对体积微小的海洋浮游植物的研究非常有限.海洋微藻是海洋生态系统最主要的初级生产者,在自然界物质和能量流动中扮演着至关重要的角色;同时,它们可以广泛应用在水产养殖、食品加工、医药保健、环境保护和生物制能等各种行业,具有非常好地开发利用前景.本文利用海洋硅藻三角褐指藻为试验材料,设置黑暗胁迫和UV辐射胁迫处理,着重测定微藻在恢复生长时期的藻生物量,叶绿素a含量和蛋白质含鼍等指标,探讨经黑暗与UV辐射胁迫后三角褐指藻的补偿生长现象.结果显示,无论是先经正常光照处理还是2 d黑暗处理,UV辐射0.1 rain和0.8 rain的微藻生物量都明显高于不经UV辐射胁迫的微藻生物置;此外,经过不同程度的黑暗与UV辐射处理后,微藻在恢复生长期的叶绿素a和蛋白质含量在某特定生长时期中明显高于对照组的叶绿素a和蛋白质含最.结果表明,三角褐指藻对外界环境变化具有适应能力,一旦不良环境胁迫被解除,微藻会表现出一定的补偿生长效应.我们的研究结果不但拓展和丰富了目前补偿生长的研究对象范围,而且还能为当前赤潮的形成、预测和防治提供一个新的研究思路,为有益经济微藻的高效率培养与利用提供理论指导.     

Carbon-nitrogen relations at whole-cell and free-amino-acid levels during batch growth of Isochrysis galbana (Prymnesiophyceae) under conditions of alternating light and dark

Isochrysis galbana Parke, Strain CCAP 927/1, was grown in ammonium-limited batch culture under a 12 h light: 12 h dark illumination cycle. Samples were taken every 12 h over the 26 d period from lag phase through exponential into stationary phase (no net carbon fixation), with more frequent sampling at points of interest. Exponential cell-specific growth rate was 0.3 to 0.4d^-1. Cell division occurred during the dark phase, while cell volume increase, ammonium uptake, and pigment synthesis occurred during the light. Stationary phase cells were small, and the lag phase was long (5 d) even though the C:N ratio had returned from 18 to 6.5 within 2 d, followed by synthesis of chlorophyll a. Net chlorophyll synthesis ceased within 4 d of exhaustion of the nitrogen source. The chlorophyll c: chlorophyll a ratio remained constant during increasing nitrogen deprivation. Biovolume and carotenoids correlated with carbon biomass. Levels of chlorophyll a correlated poorly with carbon fixation and carbon biomass once the nitrogen source had been exhausted. Except after the addition of ammonium to nitrogen-deprived cells (refeeding), the content of intracellular glutamine and the glutamine: glutamate ratio were low during the dark phase, rising to a plateau within the first 1 h of illumination. Refeeding of cells which had only just exhausted the extracellular nitrogen source resulted in a much smaller increase in glutamine than refeeding of nitrogen-starved (stationary-phase) cells. Nitrogen biomass correlated with the presence of an unidentified intracellular amine.     

Heavy metals availability (Fe, Mn, Zn, Cu and Cr) in Aden Gulf sediments under aerobic and anaerobic conditions

The present study aims to analyse the chemical speciation of heavy metals in relation to aerobic and anaerobic conditions. Two sediment samples (from the Gulf of Aden, Yemen) were incubated under flooded conditions. In particular, the chemical forms of Fe, Mn, Zn, Cu and Cr under the experimental conditions were studied using a sequential chemical extraction method. The pH and Eh of the suspension were measured as critical parameters controlling the fate of the metals in the environment. The results showed that the metals concentration in the different forms varied with time incubation and affected by the variation of redox potential and pH value. Also, the changes in both redox potential (Eh) and pH values had evident effects on heavy metals transformation. It is obvious that the highest redox potential affected the amount of iron and manganese in the oxides form. When the redox potential decreased to-133 and-170 mV, it caused a significant transformation of the Fe-Mn oxide form to the water-soluble and exchangeable fractions. Under anaerobic conditions, the relative percentage of all five metals including the summation of four fractions (the water-soluble and exchangeable, carbonate, oxides and organic fractions) constituted 45-60% of the total amount of iron, 33-50% for manganese, 33-63% for Zn, 63-74% for Cu and 19-43% for Cr. Both zinc and copper among water-soluble and exchangeable fraction were high at the end of incubation period, this accompanied by a significant decrease in the content of the organically bound fraction. In general, the reducing conditions were more favorable for metal bound to water soluble and exchangeable fraction.     

Drought induced changes in growth, leaf gas exchange and biomass production in Albizia lebbeck and Cassia siamea seedlings

Diurnal trends in net photosynthesis rate (P(N)), stomatal conductance (g(s)), water use efficiency (WUE) and biomass were compared in six-month-old seedlings of Albizia lebbeck and Cassia siamea, under different levels of drought stress. The potted plants were subjected to four varying drought treatment by withholding watering for 7 (D1), 14(D2) and 25 (D3) days. The fourth group (C) was watered daily and treated as unstressed (control). Species differed significantly (p < 0.001) in their physiological performance under varying stress conditions. Higher P(N) of 11.6 +/- 0.05 in control followed by 4.35 +/- 0.4 in D1 and 2.83 +/- 0.18 micromol m(-2) s(-1) in D2 was observed in A. lebbeck. A significant (p < 0.001) reduction in P(N) was observed in C. siamea (C 7.65 +/- 0.5 micromol m(-2) s(-1), D1, 2.56 +/- 0.33 micromol m(-2) s(-1) and D2, 1.4 +/- 0.01 micromol m(-2) s(-1)) at 9 hr. A positive correlation was seen between P(N) and g(s) (A. lebbeck, r2 = 0.84; C. siamea, r2 = 0.82). Higher WUE was observed in C. siamea (D2, 7.1 +/- 0.18 micromol m(-2) s(-1); D3, 8.39 +/- 0.11 micromol m(-2) s(-1)) than A. lebbeck, (control, 7.58 +/- 0.3 micromol m(-2) s(-1) and D3, 8.12 +/- 0.15 micromol m(-2) s(-1)). The chlorophyll and relative water content (RWC) was more in A. lebbeck than C. siamea. Maximum biomass was produced by A. lebbeckthan C. siamea. From the study, one could conclude that A. lebbeckis better than C. siamea in adopting suitable resource management strategy and be best suited for the plantation programs in the semi-arid dry lands.