Curcas Plants Research Articles

Antioxidant enzyme responses to salinity stress of Jatropha curcas and J. cinerea at seedling stage

The salt-sensitive humid tropical biodiesel crop, Jatropha curcas, was subjected to a 28-day exposure to salinity (0, 50, 100, and 200 mM NaCl), and activities of antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX), the rate of lipid peroxidation, stomatal conductance, mineral contents, and chlorophyll (Chl) content were compared to corresponding characteristics of J. cinerea, a related wild species of saline-dry areas. Biomass production decreased under the influence of 50 mM NaCl in both species, and the reduction was larger in J. curcas than in J. cinerea at the higher NaCl concentrations. In both species, stomatal conductance and transpiration decreased, leaf temperature and Na+ concentration increased under salt treatment; salinity effect was stronger in J. curcas. Chl degradation was enhanced only in J. curcas. In both Jatropha species, SOD, CAT, and POX activities increased with salinity. J. curcas showed the higher antioxidant activity than J. cinerea. Lipid peroxidation was observed only in J. curcas at concentrations above 100 mM NaCl, partially due to a greater reduction in stomatal conductance and/or the poor ROS-scavenging system. Thus, J. cinerea had more favorable characteristics to adapt to saline environments, and young J. curcas plants could adapt to salt-affected land if soil salinity was moderate (about 50 mM NaCl in solution).

Mites (Acari) associated with three species of the genus <em>Jatropha</em> (Euphorbiaceae) in Brazil, with emphasis on <em>Jatropha curcas</em>

The physic nut (Jatropha curcas L.) (Euphorbiaceae) has emerged as a new option in cultivation aimed at biodiesel production. In order to provide information that may be useful to further develop management plans for that specific crop, samples of mites were collected from cultured and wild J. curcas plants in various regions of the country and from two other species of the same genus, Jatropha gossypiifolia L. and Jatropha mollissima (Pohl) Baill. in the northeastern region of Brazil. Altogether 31 species belonging to 10 families were recorded. The family Phytoseiidae presented the largest number of species (17). Polyphagotarsonemus latus Banks (Tarsonemidae) was the most abundant species (8,503 specimens). A dichotomous key was prepared to identify all the sampled species. At least four mite species of the samples deserve attention as showing potential for being pests in the crops of J. curcas, Brevipalpus phoenicis, Brevipalpus obovatus, Polyphagotarsonemus latus and Tetranychus bastosi, the latter two often found in great abundance.

Metabolites change in Jatropha plants due to seed treatment with rhizobacteria and Rhizoctonia bataticola

An experiment on the metabolite (salicylic acid (SA), jasmonic acid (JA), hydrocyanic acid (HCN) and chitinase activity) changes owing to seed treatment with pathogen, plant growth promoting rhizobacteria (PG- PRs) - (P. maltophilia, P. fluorescens and Bacillus subtilis) alone and in combination was conducted at Chaudhary Charan Singh, Haryana Agricul- tural University, Regional Research Station, Bawal. Jatropha curcas plants raised from root rot pathogen (Rhizoctonia bataticola) treated seeds showed an initial increase in SA and hydrocyanic acid HCN content and an oppo- site trend was observed for JA level and chitinase activity. Though, PGPRs inoculation resulted in higher increase in SA level, JA level and chitinase activity in both the cases alone as well as in integration with pathogen, however, maximum increase in JA content was explicited in plants raised after seed treatment with P. fluorescens, the most effective rhizobacteria amongst PGPRs studied. Highest increase in HCN content (45 μg g -1 ) over control (24 μg g -1 ) was noticed for P. fluorescens followed by co-seed in- oculation with P. fluorescens + pathogen (43 μg g -1 ) at 10 DPI. The co-seed inoculation elicited 68 units at 10 DPI whereas the pathogen challenged plants showed lower chitinase activity with 42 units. All the metabolites de- clined slightly or sharply with age of the plant irrespective of inoculations. Keywords metabolites, Jatropha curcas, rhizobacteria, Rhizoctonia bataticola.

Effects of boron excess in nutrient solution on growth, mineral nutrition, and physiological parameters of Jatropha curcas seedlings

AbstractJatropha curcas L. has recently attracted the attention of the international research community due to its potential as a biodiesel crop. In addition, its high resistance to drought and salinity is well known. Under arid and semiarid conditions, boron (B) concentrations in irrigation water can be higher than desired when water from industry, urban areas, or desalination is used. However, the growth and physiological responses of J. curcas plants to B excess in the irrigation water are unknown. Therefore, a greenhouse experiment was conducted to study the effects of B excess in the nutrient solution (0.25, 2, 4.5, and 7 mg L–1 B, applied as H3BO3) on plant growth, mineral concentration in the different plant tissues, photosynthesis, water relations, chlorophyll fluorescence, chlorophyll concentration (as SPAD values), and composition of carbohydrates. Plant growth decreased with increasing B concentration in the nutrient solution; growth reduction was higher for roots than for leaves or stems. The B concentration increased in all plant tissues, in the following order: leaf > root > stem. These data indicate that the roots of J. curcas are more sensitive to B toxicity than the leaves and that B has restricted mobility inside these plants, accumulating mainly in the basal and middle leaves via the transpiration stream. Increasing B concentration in leaves decreased the ACO2 and the stomatal conductance, but the leaf water parameters were not affected. The data for chlorophyll concentration and chlorophyll fluorescence indicated that nonstomatal factors were involved in the ACO2 decline, whereas decreases in the parameters of PSII photochemistry due to B toxicity suggest that there was structural damage in chloroplasts. There was also a general tendency for a decrease in nonstructural carbohydrates in all plant tissues, possibly due to the decline in ACO2. With excess B, the concentrations of K and Mg increased in leaves due to a decrease in the growth, while a typical antagonistic effect between B and P was evident from the P concentration decrease in leaves. In summary, J. curcas should be considered a B‐sensitive plant, as a leaf B concentration of 1.2 mg (g dw)–1 caused a growth decline of approximately 30%.

Bioaccumulation of nutrient elements from fly ash-amended soil in Jatropha curcas L.: a biofuel crop

Fly ash (FA) from coal-burning industries may be a potential inorganic soil amendment; the insight of its nutrient release and supply to soil may enhance their agricultural use. The study was conducted to assess the ability of fly ash (a coal fired thermal plant waste) to reduce soil fertility depletion and to study bioaccumulation of mineral nutrients in Jatropha curcas grown on soils amended with fly ash. Fly ash was amended to field soil at six rates (0, 5, 10, 20, 40, and 70% w/w) on which J. curcas was grown. After 8months of growth, the height of jatropha plants was significantly increased at 5 and 10% FA-amended soil, whereas, biomass significantly increased at 5, 10, and 20% FA-amended soil compared to control soil (0% FA). Leaf nutrients uptake, followed by stems and roots uptake were highly affected by fly ash amendment to soil. Most of nutrients accumulation were increased up to 20% fly ash and decreased thereafter. The results of available nutrient analysis of soil revealed that availability of nitrogen, potassium, sulfur, copper, iron, mangnese, and zinc declined significantly at higher levels of fly ash amendments, whereas, availability of phosphorus increased at these levels. However, pH, organic carbon, and available boron were not influenced significantly by fly ash amendment to soil. Microbial biomass C, N, and ratio of microbial-C to organic C were significantly reduced at 20% fly ash and higher amounts. This study revealed that J. curcas plants could gainfully utilize the nutrients available in fly ash by subsequently amending soil.

Jatropha curcas L. Root Structure and Growth in Diverse Soils

Unlike most biofuel species, Jatropha curcas has promise for use in marginal lands, but it may serve an additional role by stabilizing soils. We evaluated the growth and structural responsiveness of young J. curcas plants to diverse soil conditions. Soils included a sand, a sandy-loam, and a clay-loam from eastern Mexico. Growth and structural parameters were analyzed for shoots and roots, although the focus was the plasticity of the primary root system architecture (the taproot and four lateral roots). The sandy soil reduced the growth of both shoot and root systems significantly more than sandy-loam or clay-loam soils; there was particularly high plasticity in root and shoot thickness, as well as shoot length. However, the architecture of the primary root system did not vary with soil type; the departure of the primary root system from an index of perfect symmetry was 14 ± 5% (mean ± standard deviation). Although J. curcas developed more extensively in the sandy-loam and clay-loam soils than in sandy soil, it maintained a consistent root to shoot ratio and root system architecture across all types of soil. This strong genetic determination would make the species useful for soil stabilization purposes, even while being cultivated primarily for seed oil.

Characterisation of Jatropha curcas seeds and oil from Mali

This publication deals with the characterisation of Jatropha curcas seeds and the oil obtained hereof. The analyzed seeds have been harvested from hedges and plantations in the regions of Teriya Bugu and Bla in Mali in the years 2009 and 2010. The oil is obtained through solvent extraction. Parameters analyzed are those which are relevant for processing of the oil into fatty acid methyl ester (FAME, biodiesel), and include acid value, fatty acid profile and contents of S, P, K, Na, Ca and Mg. All oil samples are suitable for processing into biodiesel, but some of them require pre-treatment because of high contents of free fatty acids and phosphorous. The margin of deviation of acid value and element contents throughout the oil samples depends on the way of cultivation, harvest and storage of the Jatropha curcas plants and seeds. Despite high acid values, all oil samples show high oxidation stability.

High Frequency β-glucuronidase Reporter Gene Expression in Shoot Tip, Leaf, and Hypocotyl Explants of Jatropha curcas L.

Development of a suitable genetic transformation system is the backbone of transgenic technology for efficient recovery of Jatropha curcas plants with desirable traits. Although in vitro plant regeneration protocols for shoot tip, leaf, and hypocotyl explants of J. curcas have been reported, these protocol have not been translated into efficient genetic transformation systems. The objective of this study was to standardize the parameters influencing transient β-glucuronidase reporter gene expression following Agrobacterium-mediated genetic transformation using shoot tip, leaf, and hypocotyl explants of Jatropha curcas. Disarmed Agrobacterium tumefaciens strain EHA105, harboring pCAMBIA2301 carrying neomycin phosphotransferase (nptII) as a selectable marker and the β-glucuronidase (GUS) as a reporter gene, were used for transformation. Frequencies of GUS gene expression of 86.7%, 78.3%, and 74.2% were obtained for leaf, hypocotyls, and shoot tip explants, respectively. The transgenic nature of the kanamycin-resistant explants was also confirmed by using polymerase chain reaction (PCR) assay. Because, to date, there is no report on Agrobacterium-mediated transformation of shoot tip, leaf, and hypocotyl explants of Jatropha curcas, our findings/protocol should be useful for recovering stable transgenic Jatropha curcas plants from these explants.

An efficient plant regeneration protocol from petiole explants of physic nut (Jatropha curcas L.)

Efficient and reproducible method for the in vitro regeneration of Jatropha curcas plants has been developed through direct shoot buds induction from petiole explants on Murashige and Skoog (MS) basal medium supplemented with different concentrations of thidiazuron (TDZ). The highest percentage of shoot buds induction (64.0%) was observed on MS medium supplemented with 0.52 mgL -1 TDZ with organic additives; adenine sulphate (50 mgL -1 ) + glutamine (100 mgL -1 ) + L-arginine (25 mgL -1 ) + citric acid (0.0025%) + ascorbic acid (0.005%). A maximum of six shoots per explant were elongated when explants with induced shoot buds were transferred on MS medium containing 3.0 mgL -1 6-benzyladenine (BA) and 1.0 mgL -1 indole-3-butyric acid (IBA). The regenerated shoots were rooted on half strength MS medium supplemented with 1.0 mgL -1 indole-3-acetic acid (IAA) and 0.2 mgL -1 IBA. The rooted plantlets were established in soil with more than 90% survival. Keywords: Jatropha curcas , thidiazuron, petiole, shoot buds, plantlets

Biological Characterization and Complete Genome Sequence of a Possible Strain of Indian cassava mosaic virus from Jatropha curcas in India

AbstractThe outbreak of a severe mosaic disease with a significant incidence was noticed on Jatropha curcas plants growing in Lucknow, Northern India. The causal virus was successfully transmitted by whiteflies (Bemisia tabaci) and grafting from naturally infected to healthy J. curcas plants. The association of Begomovirus with the mosaic disease of J. curcas was detected by PCR using primers specific to DNA‐A of Begomoviruses. Further, full‐length DNA‐A genome of ∼2.7 kb was amplified by RCA followed by digestion with Bam HI restriction enzyme. Cloning and sequencing of obtained amplicons resulted in 2740 nucleotides of complete DNA‐A consisting of six ORFs and IR region (GenBank Accession HM230683). The sequence analysis revealed highest 85% similarities with Jatropha curcas mosaic virus, 77–84% with Indian cassava mosaic virus and 73–76% with Sri Lankan cassava mosaic virus isolates. Phylogenetic analysis of the Begomovirus isolate also showed a clear‐cut distinct relationship with earlier reported Begomoviruses from Jatropha curcas and other Begomoviruses. On the basis of the guidelines of the International Committee on Taxonomy of Viruses (ICTV‐2008), our virus isolate was identified as a possible strain of Indian cassava mosaic virus, and its name Jatropha mosaic India virus (JMIV) is proposed.

Coordinate changes in photosynthesis, sugar accumulation and antioxidative enzymes improve the performance of Jatropha curcas plants under drought stress

The aim of this study was to assess the relationships between photosynthesis, sugars and photo-oxidative protection mechanisms in Jatropha curcas under drought stress. Leaf CO2 assimilation rate (P-N) and instantaneous carboxylation efficiency decreased progressively as the water deficit increased. The sucrose and reducing sugar concentrations were negatively and highly correlated with photosynthesis indicating a modulation by negative feedback mechanism. The alternative electron sinks (ETRs'/P-N), relative excess of light energy (EXC) and non-photochemical quenching were strongly increased by drought, indicating effective mechanisms of energy excess dissipation. The photochemistry data indicate partial preservation of photosystem II integrity and function even under severe drought. EXC was positively correlated with superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities evidencing an effective role of these enzymes in the oxidative protection against excess of reactive oxygen species in chloroplasts. Leaf H2O2 content and lipid peroxidation were inversely and highly correlated with catalase (CAT) activity indicating that drought-induced inhibition of this enzyme might have allowed oxidative damage. Our data suggest that drought triggers a coordinate down-regulation in photosynthesis through sucrose and reducing sugar accumulation and an energy excess dissipation at PSII level by non-photochemical mechanisms associate with enhancement in photorespiration, restricting photo-damages. In parallel, drought up-regulates SOD and APX activities avoiding accumulation of reactive oxygen species, while CAT activity is not able to avoid H2O2 accumulation in drought-stressed J. curcas leaves. (c) 2012 Elsevier Ltd. All rights reserved.

Contrasting Physiological Responses of Jatropha curcas Plants to Single and Combined Stresses of Salinity and Heat

In this study we evaluated the contrasting major physiological responses of Jatropha curcas L. to salinity alone and in combination with high temperature. The plants were subjected to salinity (100 mM NaCl) before and after exposure to 43 °C (heat stress) for 6 h. The effects of salinity were more harmful than heat stress, and the effects of salt stress were increased when both stress factors were combined. The negative effects of the combined treatments included strong impairment of the CO2 assimilation rate and stomata conductance and increased Na+ and Cl− accumulation in the leaves associated with increased membrane damage and lipid peroxidation. Heat favorably stimulated the accumulation of glycine betaine and chlorophyll in the salt-stressed leaves. Treatments with salt, heat, and their combination stimulated the antioxidant enzymatic defense system, that is, the expression of ascorbate peroxidase (APX) and superoxide dismutase (SOD), whereas the expression of catalase (CAT) was stimulated through treatments with salt alone and in combination with heat; treatment with heat alone did not affect CAT expression. The ascorbate redox state was decreased under salinity stress alone and in combination with heat but remained unaffected when treated with heat alone. Overall, the leaf H2O2 concentration did not change in response to these stresses, but lipid peroxidation and membrane damage was increased. Moreover, high temperature increases the negative effects of salt stress on key physiological processes, but treatment with heat alone is favorable for several metabolic indicators of young J. curcas plants. In contrast with heat, these plants exhibit higher physiological disturbances under isolated salinity stress.

High supply of NO3 − mitigates salinity effects through an enhancement in the efficiency of photosystem II and CO2 assimilation in Jatropha curcas plants

This study was performed to determine if a high supply of N-NO3 (-) is capable of mitigating negative salinity effects on photosynthesis and growth through the stimulation of nitrate assimilation, which could act as an sink from photosynthetic electron transport chain and restrict the over reduction in thylakoid membrane in Jatropha curcas leaves. The experiment was arranged in a factorial design with two nitrate concentrations (1 and 10 mM) and two NaCl levels (0 and 100 mM). Salt-stressed plants supplied with high NO3 (-) demonstrated a higher nitrate uptake rate, nitrate reductase activity and soluble-protein content when compared with plants that presented low nitrate uptake. High nitrate assimilation was associated with higher leaf growth, CO2 assimilation and lower membrane damage in salt-stressed plants. The superior performance of salt-stressed plants grown with high NO3 (-) was indicated by a higher effective quantum yield of PSII and electron transport rate and lower energy excess at the PSII level and non-photochemical quenching. Interestingly, a high NO3 (-) level in the absence of NaCl did not alter the leaf growth, photochemical activity and gas exchange parameters when compared with plants supplied with low nitrate. The proline and glycinebetaine contents were similarly increased in both low- and high-NO3 (-) salt-stressed plants. Our data suggest that the favorable effects induced by high nitrate supply were possibly associated with stimulation in the nitrate assimilatory pathway. This process might have acted as a sink of electrons from the thylakoid membranes minimizing photo-damage and stimulating CO2 assimilation under salinity in J. curcas.

Seasonal variations of photosynthesis, gas exchange, quantum efficiency of photosystem II and biochemical responses of Jatropha curcas L. grown in semi-humid and semi-arid areas subject to water stress

This study aimed to compare the physiological adaptations of Jatropha curcas in two regions with different climates, the Agreste (a semi-arid tropical climate) and the Florest zone (a semi-humid tropical climate) subject to water stress. Measurements of gas exchange and photochemical and biochemical efficiency were performed in two seasons, the dry season (September to February) and the rainy season (April and August), between 2006 and 2007. During the dry season in the Florest zone, the J. curcas plants presented better photosynthetic performance, with smaller decreases in the rates of photosynthesis, stomatal conductance and transpiration because the conditions of water availability in the soil were slightly higher than in the semi-arid region. A greater vapor pressure deficit was observed during the dry season of the semi-arid region, showing a negative correlation with the stomatal opening of the leaves, which contributed to a reduction in the values of the net photosynthetic rate. During the dry season in the semi-arid region, dynamic photoinhibition occurred in the leaves of J. curcas around mid-day, with a rapid recovery during the afternoon. However, chronic photoinhibition may have occurred in some plants with a severe water deficit. A reduction in the effective quantum efficiency was also observed during the driest months. The increase of catalase activity and the accumulation of proline, total soluble sugars and amino acids during periods of low water availability in the soil suggest that J. curcas presents an efficient protection mechanism that allows the plant to survive under drought conditions.

First Report of Curvularia lunata on Jatropha curcas in Mexico.

The Mexican nut or Jatropha curcas (Euphorbiaceae) is considered an alternative biodiesel source (2). This species is native to Mexico, but is widely distributed in Latin America, Africa, India, and Southeast Asia. Mexico has 6 million hectares with potential for cultivation of this crop (4). In Tamaulipas, Mexico, several adaptation trials have been conducted since 2008. In 2009, symptoms of Curvularia leaf spot were observed on basal leaves of 1-year-old J. curcas plants of the ecotype 'Yautepec' growing in El Mante, Tamaulipas. Spots with yellow borders originated on the edge of leaves, coalesced, and often resulted in approximately 20% leaf abscission on infected plants. Symptomatic leaves were sectioned into small pieces (0.5 cm) and gently washed with a 3:1 solution of 5% sodium hypochlorite to water and rinsed three times with sterilized distilled water. The leaf pieces were dried for 24 h on sterile filter paper, cultured on potato dextrose agar (PDA), and incubated at 27°C under continuous light for 7 days. Cultures produced pale brown conidia, relatively fusiform and cylindrical (25.6 ± 2.6 to 14.0 ± 1.6 μm) with a central cell that was slightly curved and larger and darker than the end cells. Conidia were loosely arranged on conidiophores sparsely distributed or in closer verticils (1). On the basis of the morphological characteristics, the fungus was identified as Curvularia lunata. A fraction of the mycelium grown on solid medium was inoculated into potato dextrose broth and grown for 72 h and DNA extraction was performed. PCR with primers designed for 26S and internal transcribed spacer (ITS) region were used to amplify and sequence 16S rRNA and the D2 region. This analysis resulted in 100% identity of the test isolate to GenBank Accession No. GQ328852.1 and the sequence of our isolate was submitted with Accession No. JF798505.1. Dried specimens were sent to the USA National Collection BPI. Koch's postulates were completed by testing for pathogenicity on 20 70-day-old Jatropha plants grown under greenhouse conditions. A conidial suspension (1 × 106 conidia ml-1) was prepared from monosporic cultures and hand sprayed onto test plants. Twenty plants were treated only with sterile water and used as controls. Symptoms appeared 2 weeks after inoculation, and 40 days later, all inoculated plants showed the same symptoms as those recorded in the field. Control plants did not show any disease symptoms. C. lunata was reisolated from 70% of the inoculated leaves. In Mexico, C. lunata was found on leaves of Quercus, Liquidambar, and Ananas, and was reported on cassava (Manihot esculentum), another member of the Euphorbiacea (3). To our knowledge, this is the first report of C. lunata on Jatropha in Mexico.

Developing a mathematical model for variation of physiological responses of Jatropha curcas leaves depending on leaf positions under soil flooding

The effect of soil flooding on photosynthesis, transpiration and stomatal conductance of Jatropha curcas seedlings were studied under natural environmental variables. Soil flooding reduced photosynthesis (P N), transpiration (E) and stomatal conductance (gs) in response to leaf positions of Jatropha curcas plants. Based on the results, we conclude that decrease in stomatal opening and stomatal limitation of photosynthesis, followed by decrease in individual leaf area are the main causes of reductions in carbon uptake of flooded seedlings. A mathematical relationship was successfully developed to describe photosynthesis, transpiration and stomatal response of Jatropha under soil flooding stress.

Photosynthesis and antioxidant activity in Jatropha curcas L. under salt stress

Biodiesel is an alternative to petroleum diesel fuel. It is a renewable, biodegradable, and nontoxic biofuel. Interest in the production of biodiesel from Jatropha curcas L. seeds has increased in recent years, but the ability of J. curcas to grow in salt-prone areas, such as the Caatinga semiarid region, has received considerably meager attention. The aim of this study was to identify the main physiological processes that can elucidate the pattern of responses of J. curcas irrigated with saline water, which commonly occurs in the semiarid Caatinga region. This study measured the activity of the antioxidant enzymes involved in the scavenging of reactive oxygen species, which include catalase (CAT) and ascorbate peroxidase (APX), as well as malondialdehyde (MDA) levels. The levels of chlorophyll (Chl), carotenoids, amino acids, proline, and soluble proteins were also analyzed. The net carbon assimilation rate (P N), stomata conductance (g s), and transpiration rate (E) decreased with salt stress. The activities of CAT and APX were decreased, while H2O2 and MDA levels as well as electrolyte leakage were significantly increased in salt-stressed plants compared to the untreated ones. These observations suggest that the ability of J. curcas plants resist to salt stress is associated with the activities of protective enzymes and their defensive functions. However, our results indicate that the reactive oxygen species scavenging system is not sufficient to protect J. curcas leaves against oxidative damage caused by salt stress, and, therefore, it cannot be treated as a salt tolerant plant species.

Physiological and morphological responses to flooding with fresh or saline water in Jatropha curcas

Jatropha curcas L. has recently drawn the attention of the international research community due to its potential as a biodiesel crop. Although Jatropha is relatively tolerant to drought and salinity, poorly drained production areas have suffered increasing problems associated with flooding by saline water. Since the combined effects of flooding and salinity stress are not known, the objective in this work was to investigate physiological and morphological responses of J. curcas plants to flooding by fresh water or salt water. Plant growth, leaf water relations, leaf gas exchange, chlorophyll fluorescence parameters, carbohydrate and organic solutes, and leaf mineral nutrients were determined in three month-old plants exposed to flooding for 10 days with water containing 0, 150 or 300mM NaCl. Flooding decreased shoot and root growth but there were no significant difference between 0 and 300mM NaCl treatments. In 0mM NaCl flooded plants, leaves suffered dehydration as relative water content (RWC) and leaf water potential (Ψw) decreased progressively resulting in decreased leaf turgor potential (ΨP). In 300mM NaCl flooded plants, however, Ψw remained high as leaf osmotic potential (Ψπ) decreased and ΨP increased. Increased leaf Cl− and Na+ concentration enabled this osmotic adjustment avoiding leaf dehydration but toxic values were reached in leaves. Leaf gas exchange parameters [net assimilation of CO2 (ACO2), stomatal conductance (gs)] and quantum efficiency of PSII (ΦPSII) were reduced similarly by flooding but internal CO2 concentration was highest in the 300mM NaCl treatment. Soluble sugars and starch was reduced in leaves and roots, and leaf Ca, Mg and P concentration was increased in plants under flooding. J. curcas plants are sensitive to flooding condition regardless of the level of salinity confirming their salinity tolerance even under flooded conditions.

Propagation by stem cuttings and root system structure of Jatropha curcas

Scarce knowledge about the propagation of Jatropha curcas is one of the limitations for the growth of cultivated area with this oilseed crop. The effect of stem cuttings length, basal area, and position on the branch on sprouting and early growth of jatropha plants were evaluated, and the effect of the propagation method on the structure of root system of adult plants was studied. The growth and development of Jatropha curcas plants were influenced by length and basal area of stem cuttings. Short cuttings favor early sprouting, but long and thick cuttings promote more shoot and root growth. Plants originated from stem cuttings obtained from the base of the branch grew more shoot structures (buds, stems, and leaves) than stem cutting from middle and apex of the branch. Leaf area at 75 days after planting was not influenced by the dimensions of stem cutting. The most vigorous root system was observed in the plants that originate from direct seeding, without any transplanting. Propagation using bag or root plug interferes with the formation of a deep tap root. Propagation through stem cuttings resulted in a very different root system structure, with predominance of superficial and thin roots. When the cap of a tap root is lost, the plant was able to regenerate a new root.

Suitability of the predatory mites Iphiseiodes zuluagai and Euseius concordis in controlling Polyphagotarsonemus latus and Tetranychus bastosi on Jatropha curcas plants in Brazil.

One of the most promising plant species for biofuel production in Brazil is the physic nut Jatropha curcas. Major phytosanitary problems include the attack of two pest mite species, the broad mite Polyphagotarsonemus latus and the spider mite Tetranychus bastosi. Owing to pesticide-related problems, there is an increasing demand for sustainable environmental-friendly control methods such as biological control. In this study we evaluated the suitability of the predatory mite species Iphiseiodes zuluagai and Euseius concordis in controlling P. latus and T. bastosi on J. curcas. The number of T. bastosi killed by I. zuluagai was lower than the number of P. latus consumed. Euseius concordis preyed upon both T. bastosi and P. latus but the number of prey killed was always lower in comparison with I. zuluagai. However, P. latus and T. bastosi are suitable for the development of I. zuluagai and E. concordis as oviposition of both predators did not differ in relation to prey species. The preference of I. zuluagai for leaves of plants infested by either P. latus or T. bastosi, combined with the higher values for predation obtained by this predatory mite when fed on P. latus, compared to those values obtained by E. concordis, suggests that I. zuluagai can be more efficient than E. concordis in reducing populations of P. latus and T. bastosi under field conditions. Furthermore, we report here on the first record of predatory mites associated with P. latus and T. bastosi on native J. curcas plants in Brazil. In conclusion, we emphasize the crucial importance of predatory mites as agents of natural biological control of mite pests on J. curcas in small farms.