Curcas Plantations Research Articles

Some Biological Features of <i>Aphtona whitfieldi</i> Bryant (Coleoptera: Chrysomelidae), an Insect Pest of <i>Jatropha curcas</i> L. in Burkina Faso

Aphthona whitfieldi Bryant (Coleoptera: Chrysomelidae) is a major insect pest of Jatropha curcas L. (Euphorbiacae) in Burkina Faso and other countries in West Africa. The insect pest feeds on the roots and the leaves of the plant. When the attacks are heavy, the plant may lose all its leaves and die off. Unfortunately, little information is available on the biology of this insect pest. A study was conducted on the biology of this insect pest in the Sissili province, South Burkina Faso and resulted in the knowledge of some of the biological features of the insect pest. Aphthona whitfieldi was reared from 13th July to 22th October 2015. Larvae and pupae were collected in J. curcas plantations near Leo, the capital city of the Sissili province, and brought to the laboratory for rearing. The insects were observed daily and the dimensions and the duration of each stage were recorded. We recorded two larval stages (1st and 3rd): a pre-pupa and a pupal stage. The pupa was free and white milk-like. Both the pre-pupa and the pupal stages lasted for five days. The 1st instar larva was smaller than the third one.

Study on the Biology ofCalideaspp. (Heteroptera: Scutelleridae), an Insect Pest ofJatropha curcasin South-Sudanian Zone of Burkina Faso

Jatropha curcas Linne is a nonedible oleaginous plant in the family Euphorbiaceae. Its seeds provide oil for industrial use, such as biofuels, and contribute to the livelihoods of small-scale farmers in rural areas. J. curcas is attacked by many insect pests, including Calidea spp., a heteropteran pest of its fruit and flowers. This insect was surveyed from May 2013 to January 2014 in the Sissili province of southern Burkina Faso. Calidea spp. were collected from J. curcas plantations within a radius of 15 km around the Leo township and bred in the laboratory under similar conditions. The mean ratio of fertility was 20.3% and the mean fecundity was 132 eggs. The biological cycle of the insect is composed of one egg stadium, five larval instars, and one adult stadium. Egg incubation took 6.2–8.3 d, and the five larval instars lasted between 27.1 and 30.1 d. The average life span of Calidea spp. adults was 114.6 d for females and 98.1 d for males. The female had an average size of 17.6 mm against 16.6 mm for the male. These findings are the first reported on this insect pest in Burkina Faso.

Effects of accession, spacing and pruning management on in-situ leaf litter decomposition of Jatropha curcas L. in Zambia

Jatropha curcas L. leaf litter decomposition and subsequent nutrient release was monitored in three experimental J. curcas plantations in Zambia, comparing accessions from six countries, pruned versus non-pruned and different plant spacings. Leaf litter production was low (267–536 kg ha−1 at the end of the growing season) and contained, on average, 1.23% N, 0.14% P and 2.61% K. Litter decomposed rapidly, losing 80% of total mass between 70 and 105 days after incubation in the field and followed a negative exponential pattern with an average decomposition constant, k, of 0.08 week−1. No significant effects of plant accession, plant spacing or pruning on the decomposition rate were detected. K, P, Mg and Na had nutrient release rates exceeding mass loss, explained by their high mobility and solubility, together with high soil temperature and rainfall conditions. Others, such as Ca and Mn, were initially retained in the decaying leaf litter before later release. The rate of N release closely approached that of mass loss. J. curcas litter can be a supplemental source of nutrients in areas known for nutrient deficiency and low organic matter, which represents an additional input in intercropping systems above biofuel production. Considering that the total primary nutrient input through J. curcas litterfall to the soil is limited (for example, for nitrogen between 9.7 and 14.2 g kg−1 and for phosphorus between 0.8 and 1.9 g kg−1), organic or mineral fertilizer application remains crucial to satisfy fully the nutrient requirements of surrounding crops.

Cultivation of Jatropha curcas L. leads to pronounced mycorrhizal community differences

Plantations of Jatropha curcas for biodiesel production in tropical and sub-tropical regions are currently booming. Although Jatropha species are well known for synthesizing a range of toxicants, the effects of J. curcas monoculture on the symbiotic status of staple crops and trees have hardly been investigated. We transferred to the greenhouse soil samples collected from 3 J. curcas plantations established 1, 2 and 15 years ago in Senegal, together with soil samples from the corresponding adjacent fallow plots. We tested whether the modification of the original chemical and microbial soil properties induced by the development of J. curcas could alter the growth of common local crops (millet, cowpea) and of a local tree (Acacia seyal), all grown in pots. We also investigated effects at the scale of the root mycorrhizal community by determining root colonization patterns (frequency, intensity) and taxonomic diversity (18S rDNA sequencing). Pronounced compositional shifts in root mycorrhizal communities were almost systematically observed between Glomeraceae and Gigasporaceae, or in some cases within Glomeraceae. Biomass and N–P shoot contents were often higher in J. curcas-grown soils. In conclusion, the altered composition of the soil mycorrhizal communities in response to the development of J. curcas did not have detrimental effects on local staple crops. The functional consequences of such modified mycorrhizal assemblages should now be further investigated under more stressful conditions.

Soil microbial diversity shift as affected by conversion of shallow and rocky wastelands to Jatropha curcas L. plantation

The cultivation in wastelands of Jatropha curcas as a biofuel crop avoids the alleged food vs. fuel dilemma. Converting wastelands into Jatropha plantation will produce changes in microbial composition which in turn may have a profound effect on biochemical activities and physico-chemical properties of soil. These changes may be permanent and the soil may attain a different equilibrium through this land use change. The objective of this study was to compare the microbial diversity of native undisturbed soil of barren rocky wasteland and soil drawn from 24 months old J. curcas plantation. Cultivation of Jatropha employing suitable agronomic practices improved soil organic carbon, available P and K. Total soil DNA extracts were used as template DNA to amplify 16S and 18S rDNA gene fragments that were further sequenced and taxonomically assigned by comparisons with gene bank resources. Diversity indices showed that the microbial diversity was higher and more evenly distributed in native soil than in Jatropha planted soil. A prominent diversity shift from Ascomycota in the native soil to Basidiomycota and Chytridiomycota in the Jatropha bulk soils was observed. Interestingly, the conversion from barren land to Jatropha cultivation with recommended agricultural practices also brought about a marked decrease in population of several fungal pathogens. There was a striking increase in members of Proteobacteria (1.7-fold) as well as of Bacteroidetes in Jatropha planted soil as compared to native soil. In contrast, there was a decrease in the Acidobacteria and Chloroflexi community in Jatropha planted soil. It would be useful to follow the microbial pattern over the long term and to study the evolution of the Jatropha soil ecosystem on wastelands.

The use of biomass production and allometric models to estimate carbon sequestration of Jatropha curcas L. plantations in western Burkina Faso

The topic of carbon sequestration in plants has received much attention recently due to concerns about global climate change, which is being exacerbated by deforestation. In the early days of the global bioenergy boom, the private sector and non-government organizations enthusiastically promoted the planting of Jatropha curcas L. as a key candidate shrub species for the production of bioenergy in West Africa. This study investigates the aboveground biomass production and carbon sequestration potential of J. curcas, which is already widely cultivated for the production of oil seeds, biodiesel and biokerosene. The specific objective is to use a destructive method to develop allometric prediction equations of the aboveground biomass production of J. curcas plantations. 38 J. curcas shrubs were harvested and weighed in order to estimate biomass production. These data were used to develop allometric equations for the estimation of wood, leaf and total aboveground biomass production. The best-fit models found for estimating shrub component biomass and total aboveground biomass production were of the power form. All of the regression equations relating the prediction of leaf biomass, wood biomass and total aboveground biomass with J. curcas diameter at 20 cm above the ground (D) were statistically significant (p < 0.001) and also presented the highest goodness of fit (high R2). The aboveground biomass carbon content was estimated using the ash method. Carbon content in leaves and wood was, respectively, 48 and 54 %. The current established allometric equations can be helpful to provide a rapid estimation of the aboveground biomass and C stock for J. curcas biofuel projects in semi-arid conditions.

Insufficient Evidence of Jatropha curcas L. Invasiveness: Experimental Observations in Burkina Faso, West Africa

Biofuel plants such as Jatropha curcas L. have potential to support the livelihoods of rural communities and contribute to sustainable rural development in Africa, if risks and uncertainties are minimized. Yet, recent papers have warned of the risk of biological invasions in such tropical regions as a consequence of the introduction of exotic biofuel crops. We investigated the seed dispersal risk and invasiveness potential of both J. curcas monoculture plantations and live fences into adjacent cultivated and uncultivated land use systems in Sissili province, Burkina Faso. Invasiveness potential was assessed through (i) detecting evidence of natural regeneration in perimeters around J. curcas plantations and live fences, (ii) assessing seed dispersal mechanisms, and (iii) assessing seedling establishment potential through in situ direct seed sowing. Spontaneous regeneration around the plantation perimeters of the three sites was very low. Individual seedling density around J. curcas live fences was less than 0.01 m−2 in all sites. Seventy percent of the seedlings were found close to the live fence and most of them derived from the same year (96 %), which indicates low seed-bank longevity and seedling survival. J. curcas can be dispersed by small mammals and arthropods, particularly rodents and ants. In some sites, such as in Onliassan, high secondary seed dispersal by animals (up to 98 %) was recorded. There were highly significant differences in germination rates between seeds at the soil surface (11 %) and those buried artificially at 1–2-cm depth (64 %). In conclusion, we failed to find convincing evidence of the spreading of J. curcas or any significant impact on the surrounding environment.

Évaluation du potentiel de dix accessions de &lt;i&gt;Jatropha curcas&lt;/i&gt; L. (Euphorbiaceae) au Niger

Objective: A trial of the ten accessions for J curcas was carried out at regional Agricultural Research Center of Maradi in Niger, with aim to evaluate the performance of Jatropha curcas accessions.Methodology and results: Each accession was represented by two rows and each row has 15 plant trees of J. curcas. Data on the rate of survival and growth parameters of each tree were collected. Results revealed that there is no significant difference between accessions tested for height and diameter. Accessions Katil 13 and GB 14 respectively originated from Mali and Bisseau Guinea were best adapted for the Niger conditions. The yield value of 511 and 445 kg per hectare respectively obtained from Katil 13 and GB 14 in 2012.Conclusion and application of results: The Government of Niger has drawn attention to this crop and has launched a J. curcas plantation for seed production of 150 ha at Guessalbodi. National Research Institution. NGOs are also involved in J. curcas plantation for biofuel use.Keywords: Jatropha curcas adaptation; yield; Niger.

Évaluation du potentiel de dix accessions de &lt;i&gt;Jatropha curcas&lt;/i&gt; L. (Euphorbiaceae) au Niger

Objective: A trial of the ten accessions for J curcas was carried out at regional Agricultural Research Center of Maradi in Niger, with aim to evaluate the performance of Jatropha curcas accessions.Methodology and results: Each accession was represented by two rows and each row has 15 plant trees of J. curcas. Data on the rate of survival and growth parameters of each tree were collected. Results revealed that there is no significant difference between accessions tested for height and diameter. Accessions Katil 13 and GB 14 respectively originated from Mali and Bisseau Guinea were best adapted for the Niger conditions. The yield value of 511 and 445 kg per hectare respectively obtained from Katil 13 and GB 14 in 2012.Conclusion and application of results: The Government of Niger has drawn attention to this crop and has launched a J. curcas plantation for seed production of 150 ha at Guessalbodi. National Research Institution. NGOs are also involved in J. curcas plantation for biofuel use.Keywords: Jatropha curcas adaptation; yield; Niger.

Understanding bioenergy conflicts: Case of a jatropha project in Kenya's Tana Delta

In recent years, conflicts related to tenure, management and utilization of natural resources, in particular bioenergy conflicts, are becoming increasingly common. Many bioenergy conflicts are related to plantation projects seeking to capitalize on the opportunity to profit from a combination of factors, centred on the enabling environment for biofuel plantation establishment found in many developing countries. This study analyses these and other related issues in a conflict in the Tana Delta in Kenya. The conflict is centred on a proposed 65,000ha Jatropha curcas plantation for biodiesel by the Canadian company Bedford. Ethical Analysis, a conflict management and research tool, was employed to better understand the underlying conflict causes. Shortcomings in the technical feasibility studies and participatory planning processes were revealed, including a poor understanding of the different interests and values with regard to land tenure and traditional rights. While the adoption of Free, Prior and Informed Consent (FPIC) is proposed, also capacities and the regulatory framework need to be strengthened to improve transparency, coordination, impact assessment and investment security. The study proposes ways to manage the ongoing conflict and discusses its implications for bioenergy governance.

Drivers and Consequences of the First Jatropha curcas Plantations in Mexico

Jatropha curcas has received great attention and national support by Mexican authorities interested in promoting cash crops to alleviate poverty and rural crises. Thus, several states have implemented programs to sponsor its cultivation and research. This paper analyzes the policies generated by the Mexican government to promote the establishment of Jatropha plantations for biofuel purposes. The supporting schemes, the state-of-the-art national research and the environmental implications of establishing this new crop were reviewed to assess their impact on small-scale producers that participated in these programs. Scientific research on native germplasm indicates the existence of great diversity in Mexico, including non-toxic ecotypes, from which highly productive varieties are being developed. However, when the plantation programs started, producers were not technically or economically prepared to face the risks associated with this new crop, nor was there a good internal supply-chain. Consequently, some programs have been abandoned and the low productivity and income generated by the plantations have not satisfied producer expectations. Thus, there is a need to review the national strategy to support this crop and to develop a well-structured biofuel market in the country for the success of Jatropha plantations in Mexico.

Observations on ecosystem services in Jatropha curcas plantations established in degraded lands in India

Jatropha is a potential biofuel crop suitable for growth on degraded lands. There is no conflict between food and fuel with the use of this plant. Against this backdrop, the research of our institute has been focused on cultivation on wastelands, where conventional crops cannot thrive. If merely neglected, wastelands are further degraded and eventually become deserts. These barren lands naturally sustain low diversity of flora and fauna and can support only abysmal ecosystem services. Jatropha cultivation has been shown to improve the soil properties of such lands. This article documents different flora and fauna frequently observed in the transformed ecosystem brought about by the resultant land use change. The article also discusses the ecosystem services gained in the process. Thus, economic and climate change benefits result from Jatropha cultivation in wastelands.

Biodiesel production from Jatropha curcas: Integrated process optimization

Energy obtained from renewable sources has increased its participation in the energy matrix worldwide, and it is expected to maintain this tendency. Both in large and small scales, there have been numerous developments and research with the aim of generating fuels and energy using different raw materials such as alternative crops, algae and lignocellulosic residues. In this work, Jatropha curcas plantation from the North West of Argentina was studied, with the objective of developing integrated processes for low and medium sizes farms. In these cases, glycerine purification and meal detoxification processes represent a very high cost, and usually are not included in the project. Consequently, alternative uses for these products are proposed. This study includes the evaluation of the Jatropha curcas crop during two years, evaluating the yields and oil properties. The solids left after the oil extraction were evaluated as solid fuels, the glycerine and the meal were used to generate biogas, and the oil was used to produce biodiesel. The oil pretreatment was carried out with the glycerine obtained in the biodiesel production process, thus neutralizing the free fatty acid, and decreasing the phosphorous and water content.

Variation in soil microbial biomass in the dry tropics: impact of land-use change

The impact of land-use change on soil microbial biomass carbon (C) and nitrogen (N) was studied through two annual cycles involving natural forest, degraded forest, agroecosystem and Jatropha curcas plantation. Soil microbial biomass C and N, soil moisture content and soil temperature were analysed at upper (0–10 cm), middle (10–20 cm) and lower (20–30 cm) soil depths during the rainy, winter and summer seasons. The levels of microbial biomass C and N were highest in the natural forest, followed in decreasing order by Jatropha curcas plantation, degraded forest and the agroecosystem. The highest level of soil microbial biomass C and N was observed during summer, decreasing through winter to the minimum during the rainy season. Soil microbial biomass C and N decreased with increasing soil depth for all land-use types, and for all seasons. Seasonal variation in soil microbial biomass was better correlated with the soil moisture content than with soil temperature. The microbial biomass C/N ratio increased with the soil depth for all land-use types, indicating changes in the microbial community with soil depth. It is concluded that the change in land-use pattern, from natural forest to other ecosystems, results in a considerable decrease in soil microbial biomass C and N. Jatropha plantation may be an alternative for the restoration of degraded lands in the dry tropics.

Effect of irrigation, nitrogen and potassium on seed yield and oil content of Jatropha curcas in coarse textured soils of northwest India

Potential of Jatropha curcas L. for producing energy from marginal land without inputs has recently drawn the attention, resulting in the planning of large commercial plantations in India and other countries. Major challenge for the extended use of J. curcas seems to be the lack of information on agro-technology and specially the water and nutrient management on its potential yield under sub-optimal and marginal conditions. Therefore, it is very difficult to estimate the yields from future plantations under sub-optimal growth conditions, the situations where J. curcas is supposed to grow. The impacts of irrigation and nutrients on seed and oil yield of J. curcas in semi-arid conditions of northwest India are discussed here. An experiment was conducted for consecutive three years (2009–2011) at CCS HAU, Regional Research Station, Bawal (Haryana), India, in three years old J. curcas plantation raised at spacing of 3m×3m in loamy sand, N deficient and medium K status soil. The treatments were comprised of three levels of irrigations viz.; no irrigation (I0), one irrigation (I1) and two irrigations (I2), four levels of nitrogen (N) i.e.; 0, 30, 60 and 90kgNha−1 and four levels of potassium (K) i.e.; 0, 30, 45 and 60kgK2Oha−1. J. curcas seed yield increased from 163.71kgha−1 with no irrigation to 472.51kgha−1 at 90kgN and 60kgK2Oha−1 with two irrigations. J. curcas seed yield increased significantly at 60kgNha−1 with no irrigation whereas seed yield increased significantly up to 90kgNha−1 with one and two irrigations. The significant effect of potassium application on seed yield was found up to 45K2Oha−1 in the absence of irrigation but its effect was significant up to 60kgK2Oha−1 with one and two irrigations. The seed oil content and oil yield of J. curcas also increased due to irrigation, nitrogen and potassium application .The maximum oil content (34.52%) and oil yield (163.31kgha−1) was recorded at 90kgN and 60kgK2Oha−1 with two irrigations. However, poor seed and oil yield of 291.55 and 89.13kgha−1 respectively was obtained under sub-optimal conditions i.e.; one irrigation with 30kgN and 30kgK2Oha−1.

Invasiveness risk of the tropical biofuel crop Jatropha curcas L. into adjacent land use systems: from the rumors to the experimental facts

AbstractJatropha curcas L. produces seeds rich in non‐edible oil suitable for biodiesel but it has been categorized as invasive. Although not scientifically verified, this allegation has resulted in a cultivation ban in several countries. In this article we report an integrated series of observations and experimental findings from invasiveness research in Zambia. We studied the impacts of J. curcas plantations on adjacent land use systems focusing on spontaneous occurrence of seedlings, seed dispersal mechanisms, seed predation by animals, and germination success of dispersed seeds. No spontaneous regeneration was observed in land use systems adjacent to J. curcas plantations. Primary seed dispersal was limited, predominantly under the canopy of the mother plant. Rodents and shrews dispersed and predated J. curcas seeds and fruits. They transported the seeds up to 23 m from the sources and repositioned them in their burrows up to 0.7 m deep, but none of these seeds could establish. Germination experiments in adjacent land use systems revealed 4% germination success at the soil surface, and 65% if buried artificially at 1–2 cm depth, yet the latter is unlikely to occur under natural conditions. These findings show that J. curcas seeds may be dispersed by animals to adjacent land use systems, but no natural recruitment was observed given low germination on the surface and none in burrows. Altogether these results suggest that the plant currently does not show an elevated risk of invasion to adjacent land use systems, at least in the investigated case study. But more long‐term studies, also in other growing areas are needed to corroborate these results.

Carbon sequestration and land rehabilitation through Jatropha curcas (L.) plantation in degraded lands

The effects of growing Jatropha in on-farm and on-station degraded lands were evaluated on carbon (C) sequestration and soil properties. Jatropha accumulated and added to soil significant amounts of C (305kgha−1year−1) from the year one itself. Overall, a 3–5-year old plantation added per year around 4000kg plant biomass equivalent to 1450kgCha−1 – 800kg C through leaves, 150kg C through pruned twigs, and 495kg C as deoiled Jatropha cake. Biodiesel C replacement in the fossil fuel was 230kgha−1. Besides adding biomass to the soil, and C replacement in fossil fuel; the standing Jatropha rendered ecosystem service by fixing 5100–6100kgha−1C as the aboveground plus belowground biomass. Carbon additions by Jatropha during 4 years increased C content in the degraded surface soil layer by 19%, resulting in about 2500kgha−1C sequestered. Huge C additions and live root activity under Jatropha increased microbial population, respiration rate and microbial biomass C and N in soil. Along with C additions, 4000kgha−1year−1 plant biomass recycled into the soil 85.5kg nitrogen, 7.67kg phosphorus, 43.9kg potassium, 5.20kg sulphur, 0.11kg boron, 0.12kg zinc and other nutrients. The C additions improved water holding capacity of the soil under Jatropha as compared with the adjacent control soil which increased by 35% at 30kPa and 21% at 1500kPa soil water potential.

Water requirement and use by Jatropha curcas in a semi-arid tropical location

Increasing emphasis on biofuel to meet the growing energy demand while reducing emissions of greenhouse gases, Jatropha curcas has attracted the attention of researchers, policy makers and industries as a good candidate for biodiesel. It is a non-edible oil crop, drought tolerant and could be grown on degraded lands in the tropics without competing for lands currently used for food production. J. curcas being a wild plant, much about its water requirement and production potential of promising clones in different agroclimatic conditions is not known. Water use assessment of J. curcas plantations in the semi-arid tropical location at ICRISAT, Patancheru indicated that crop evapotranspiration of J. curcas under no moisture stress varied from 1410 to 1538 mm per year during 2006–2009. Under field conditions the crop evapotranspiration varied from 614 to 930 mm depending on the atmospheric demand, rainfall and crop phenological stage. Patterns of soil-water depletion indicated that with growing plant age from two to five years, depth of soil-water extraction increased from 100 to 150 cm by fifth year. Monthly water use of Jatropha varied from 10–20 (leaf shedding period) to 140 mm depending on water availability and environmental demand. This study indicated that J. curcas has a good drought tolerance mechanism, however under favorable soil moisture conditions Jatropha could use large amounts of water for luxurious growth and high yield. These findings highlight the need to carefully identify suitable niche areas for Jatropha cultivation and assess the implications of large J. curcas plantations on water availability and use under different agroecosystems, particularly so in water scarce regions such as semi-arid and arid regions in the tropics.

PlantingJatropha curcason Constrained Land: Emission and Effects from Land Use Change

A study was carried out to assess carbon emission and carbon loss caused from land use change (LUC) of converting a wasteland into a Jatropha curcas plantation. The study was conducted for 12 months at a newly established Jatropha curcas plantation in Port Dickson, Malaysia. Assessments of soil carbon dioxide (CO2) flux, changes of soil total carbon and plant biomass loss and growth were made on the wasteland and on the established plantation to determine the effects of land preparation (i.e., tilling) and removal of the wasteland's native vegetation. Overall soil CO2 flux showed no significant difference (P < 0.05) between the two plots while no significant changes (P < 0.05) on soil total carbon at both plots were detected. It took 1.5 years for the growth of Jatropha curcas to recover the biomass carbon stock lost during land conversion. As far as the present study is concerned, converting wasteland to Jatropha curcas showed no adverse effects on the loss of carbon from soil and biomass and did not exacerbate soil respiration.

The Significance of Pollination Services for Biodiesel Feedstocks, with Special Reference to Jatropha curcas L.: A Review

The importance of pollination services for insect-pollinated crops in general, and for the major biodiesel crops, such as Jatropha curcas L., in particular, is reviewed. The dependence of the major biodiesel feedstocks on pollinators ranges from almost zero to low dependence in soybean, through low to medium dependence in rapeseed, and up to high dependence in the African oil palm and in J. curcas. Currently, the basic requirement of J. curcas for pollination services is largely neglected. In light of the enormous scale of existing and future plantations of J. curcas, and of the effective pollination by native pollinators in most commercial crops, it is clear that the local insect fauna of any given habitat, on any continent, will not be able to satisfy the pollination requirements of any plantation, once it becomes established and starts blooming. It is suggested that the best way to address the pending catastrophe of severely reduced yields in J. curcas plantations that would result from reduced reproductive success would be to use honeybees as the prime pollinators, regardless of the pollination services provided by the local insect fauna. Basic research on the contribution of honeybees to the reproductive success of J. curcas should be carried out and used as a guideline for planning future provision of proper honeybee pollination services in any given plantation, characterized by its specific size, age, planting density, soil type, irrigation, fertilization, and climatic conditions.