Adverse Effects Of Drought Research Articles

The impact of Drought and Climate Change on economy, environment and human health in Southern Iran: A qualitative study

Drought and climate change are one of the most important environmental health challenges of the current century. It has been predicted that the occurrence of drought, its intensity, and its adverse effects on the environment, human health, societies, and economy will increase in the coming decades. This qualitative content analysis study aimed to explore the impact of drought on the lives of people living in the south of Iran. Data were collected through in-depth semi-structured interviews with farmers, urban and rural officials, and physicians. A total of 25 interviews were conducted. All interviews were recorded and then transcribed. Data were analyzed using MAXQDA version 18. The concepts raised by interviewees regarding the consequences of drought were categorized into four themes, including economic consequences, environmental hazards, health consequences, and adaptation options; and most of these consequences were inter-related. Participants believed that drought has affected the soil, environment, ecosystem, and the quality and quantity of water, and this can lead to extensive effects on humans’ physical, mental, and community wellbeing. Drought can also cause adverse economic effects, which can further intensify its adverse effects. It seems like the adverse effects of drought in Iran are severe and destructive, and this is due to the mismanagement of water and environmental resources and other socio-economic problems. Fundamental changes in the management of water and environmental resources are necessary.

UV-C Priming Enhances Water Stress Tolerance in Broccoli (Brassica Oleracea, L.) and Its Germination Rate

Germination of broccoli seeds exposed to UV-C radiation (priming) for a 30-minute period and tolerance to water stress was evaluated. These findings suggest that the adverse effect of drought on the germination rate can be circumvented by seeds primed with a UV-C radiation at a wavelength of 254 nm during 30 min.

Phytohormones unlocking their potential role in tolerance of vegetable crops under drought and salinity stresses.

Globally, abiotic stresses are drastically reducing the productivity of vegetable crops. Among abiotic stresses, drought and salinity are more challenging constraints for the sustainable production of vegetables. A great variety of vegetables are facing dry and hot summer spells, poor water availability, and higher salinity mainly due to irrigation with brackish water. Vegetables are considered higher water-dependent crops, requiring water for proper growth and yield. Drought and salinity impair plant metabolism. The disruption in plant metabolism leads to a reduction in growth, developmental processes, and ultimately crop yield. Appropriate management measures are needed to cope with the adverse effects of drought and salinity. Different agronomic and molecular approaches contributed to improving tolerance. Therefore, the present review significantly explores the impact of phytohormones on vegetable crops under drought and salinity stresses. Phytohormones (salicylic acid, melatonin, jasmonates, Brassinosteroids, ascorbic acid, and numerous others) can be sprayed for improvement of plant growth, yield, and photosynthetic pigments by modulation of physiological and biochemical processes. In this manner, these phytohormones should be explored for sustainable production of vegetable crops growing under abiotic stress conditions.

Role of maturation and mortality in portfolio effects and climate resilience

The portfolio effect plays a critical role in population productivity and stability. Age structure of spawning salmon represents an example of portfolio effects such that the risks of experiencing unfavorable conditions are spread across time. However, the distribution of maturation ages for Pacific salmon ( Oncorhynchus spp.) is increasingly concentrated into fewer and younger ages, which may impact population resilience to climate change. We explored the population dynamics of Sacramento River fall-run Chinook salmon ( O. tshawytscha) under different age structure scenarios using a life-cycle model and compared two mechanisms that can underlie these changes—mortality and maturation. In addition, we tested whether age structure promotes resilience to drought. We found that high age structure diversity increased the stability of population size and harvest compared with low diversity. However, mean population size responded differently depending on the underlying mechanism. Reduced mortality of adult fish ages 4–5 increased escapement, whereas delayed maturation decreased escapement. Overall, high age structure diversity was able to buffer against the adverse effects of droughts by reducing the variability of population size and harvest compared with low diversity. Our results suggest that age structure promotes stability of salmon in an increasingly variable climate.

Salicylic Acid Application Mitigates Oxidative Damage and Improves the Growth Performance of Barley under Drought Stress

Drought is a severe environmental constraint, causing a significant reduction in crop productivity across the world. Salicylic acid (SA) is an important plant growth regulator that helps plants cope with the adverse effects induced by various abiotic stresses. The current study investigated the potential effects of SA on drought tolerance efficacy in two barley (Hordeum vulgare) genotypes, namely BARI barley 5 and BARI barley 7. Ten-day-old barley seedlings were exposed to drought stress by maintaining 7.5% soil moisture content in the absence or presence of 0.5, 1.0 and 1.5 mM SA. Drought exposure led to severe damage to both genotypes, as indicated by phenotypic aberrations and reduction of dry biomass. On the other hand, the application of SA to drought-stressed plants protected both barley genotypes from the adverse effects of drought, which was reflected in the improvement of phenotypes and biomass production. SA supplementation improved relative water content and proline levels in drought-stressed barley genotypes, indicating the osmotic adjustment functions of SA under water-deficit conditions. Drought stress induced the accumulation of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2) and superoxide (O2 •− ), and the lipid peroxidation product malondialdehyde (MDA) in the leaves of barley plants. Exogenous supply of SA reduced oxidative damage by restricting the accumulation of ROS through the stimulation of the activities of key antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) and glutathione peroxidase (GPX). Among the three-applied concentrations of SA, 0.5 mM SA exhibited better mitigating effects against drought stress considering the phenotypic performance and biochemical data. Furthermore, BARI barley 5 showed better performance under drought stress than BARI barley 7 in the presence of SA application. Collectively, our results suggest that SA played a crucial role in improving water status and antioxidant defense strategy to protect barley plants from the deleterious effects of water deficiency.

Foliar application of hydrogen peroxide (H2O2) modulates growth, inorganic ion and osmolyte accumulation of soybean (Glycine max) cultivars under drought stress

• Sensitivity to drought differed among the cultivars and depends on the severity of stress. • Cultivars-1 and 2 shows stronger tolerance mechanism to drought condition. • Foliar application of H 2 O 2 enhanced glycine betaine and total soluble sugar. • H 2 O 2 differentially induced accumulation of inorganic ion among the cultivars. Soybean ( Glycine max ) is a valuable and highly nutritional crop with many cultivars in the Temperate and Tropical environments but threatened by drought. Further to this, the application of signaling molecules as ameliorative strategy against adverse effects of drought on soybean cultivars still remains unclear. This study investigates the variation in drought tolerance and effects of foliar application of hydrogen peroxide (H 2 O 2 ) on drought stress in three soybeans cultivars (NGBO 03519 , 03515 and 03524) under normal irrigation, mild drought and severe drought. Mild and severe drought exerted negative effects on growth and metabolic processes of G. max cultivars. Severe drought decreased the photosynthetic pigments in all cultivars, but substantially increased the root biomass and triggered the accumulation of glycine betaine in NGBO 03519 and NGBO 03515. Drought significantly enhanced total soluble sugar in NGBO 03515 and NGBO 03524 cultivars while severe drought decreased Ca 2+ , Mg 2+ , Cl − , and SO 4 2− in NGBO 03524. Foliar-applied H 2 O 2 ameliorated impact of drought and positively enhanced biomass, photosynthetic pigment, ion accumulation, and consequently resulted into improved plant growth. The results indicated that H 2 O 2 sustained higher cell turgor in NGBO 03515 and NGBO 03524 cultivars by significantly enhancing K + under severe drought. Conclusively, the study indicated that while NGBO 03519 may have sturdy fitness to resist severe drought, H 2 O 2 is essential for cell expansion and growth of NGBO 03515 and 03524.

Drought timing and severity affect radial growth of Picea crassifolia at different elevations in the western Qilian Mountains.

In the context of continued global climate change, the intensity and frequency of droughts have increased to varying degrees in many places. Due to the complexity of drought events, the mechanisms by which trees respond to drought are not well understood. In this study, we analyzed the growth trends of Qinghai spruce (Picea crassifolia) at different elevations in the western part of Qilian Mountains and the dynamic response to climate change. We also compared the differences in radial growth of trees at different elevations in response to drought events in the growing and non-growing seasons based on resistance (Rt), recovery (Rc), and resilience (Rs). The results showed that (1) trees at all three elevations were limited by drought stress and the lower the elevation the more sensitive the trees were to drought. (2) The response of middle- and low-elevation trees to the standardized precipitation evaporation index in June of that year was stable. (3) Growing season drought limits radial growth of trees more than non-growing season drought, and Rt is smaller and Rc is larger at low elevations. With increasing drought severity, trees at all three elevations exhibited a trend of decreasing Rt and Rs and increasing Rc. (4) There were significant differences in the growth trends of trees at the three elevations. Therefore, we should continuously pay attention to the dynamics of the forest ecosystem in the western part of Qilian Mountains and take improved measures to cope with the adverse effects of drought on Qinghai spruce.

Acetic acid alters rhizosphere microbes and metabolic composition to improve willows drought resistance

The adverse effects of drought on plants are gradually exacerbated with global climatic change. Amelioration of the drought stress that is induced by low doses of acetic acid (AA) has been caused great interest in plants. However, whether AA can change soil microbial composition is still unknown. Here, we investigated how exogenous AA regulates the physiology, rhizosphere soil microorganisms and metabolic composition on Salix myrtillacea under drought stress. The physiological results showed that AA could improve the drought tolerance of S. myrtillacea. Azotobacter and Pseudomonas were enriched in the rhizosphere by AA irrigation. AA significantly increased the relative contents of amino acid metabolites (e.g., glycyl-L-tyrosine, l-glutamine and seryl-tryptophan) and decreased the relative contents of phenylpropane metabolites (e.g., fraxetin and sinapyl aldehyde) in soils. The enrichments of Azotobacter and Pseudomonas were significantly correlated with glycyl-L-tyrosine, l-glutamine, seryl-tryptophan, fraxetin and sinapyl aldehyde, which could increase the stress resistance by promoting nitrogen (N) uptake for willows. Furthermore, inoculation with Azotobacter chroococcum and Pseudomonas fluorescens could significantly improve willows drought tolerance. Therefore, our results reveal that the changes of plant physiology, rhizosphere soil microorganisms and metabolic composition induced by AA can improve willows drought resistance by enhancing N uptake.

Projected Increases in Global Terrestrial Net Primary Productivity Loss Caused by Drought Under Climate Change

AbstractUnderstanding present and future impacts of drought on the terrestrial carbon budget is of great significance to the evaluation of terrestrial ecosystem disturbance and terrestrial carbon sink. Here, we evaluate the effect of vegetation net primary productivity (NPP) associated with drought through the difference between the mean NPP in the drought and normal years during a specific time period (30 years). Then, the NPP effects in different vegetation types and climatic zones under baseline stage (1981–2010) and future climate scenarios (RCP2.6, RCP4.5, and RCP8.5) is assessed. The results indicate that the negative NPP extremes are captured in most regions, except for the high‐latitude in the Northern Hemisphere. The NPP loss caused by extreme droughts in 2071–2100 is largest under RCPs, followed by the effects of severe and moderate droughts. Regionally, central United States, southern Africa, central Asia, India, Amazon tropical rainforest, and Australia are projected to experience a significant increase in negative NPP extremes and most of these regions are in arid and semi‐arid and tropical rain forest areas. In contrast, tropical Asia suffers little drought effects. For different vegetation, Evergreen Broadleaf Forest, Closed Shrubland, Open Shrubland, Croplands, and Grassland are the most affected by drought. The largest NPP loss occurs in most part of regions under RCP4.5 scenario, not RCP8.5. Climate change is projected to play the largest role in aggravating the risk of drought‐induced NPP reduction. And meanwhile, the adverse effects of drought on vegetation may be resisted through rational fertilizer utilization and land management in future.

Exogenous melatonin alleviated growth inhibition and oxidative stress induced by drought stress in apple rootstock

Drought stress is one of the major environmental obstacles that limit the production and development of apples (Malus domestica Borkh.). The role of melatonin is well known in the protection of plants under environmental stresses. In this study, we investigated the effect of melatonin on apple rootstock M. hupehensis Rehd under drought stress. The results showed that drought inhibited the growth of M. hupehensis and dramatically reduced root surface area, root volume, the number of tips and forks, and root diameter. Drought-induced growth inhibition was significantly decreased by adding melatonin. Net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), stomatal conductance (Gs), transpiration rate (Tr), were markedly reduced under drought stress. However, the application of melatonin could mitigate the damage to the photosynthetic apparatus and increase the quantum yield of PSII photochemistry. Additionally, generation of hydrogen peroxide (H2O2) and superoxide radicals (O2•–) sharply increased in apple leaves after 4 days under drought stress, and the accumulation of electrolyte leakage (EL) represented oxidative stress, while by applying melatonin under drought stress, the generation of O2•– and H2O2 were significantly reduced and protected the membrane from drought damages. These results suggest that the adverse effects of drought can be minimized by applying melatonin to apples.

The Response of Antioxidant System of Drought-Stressed Green Pea (Pisum sativum L.) Affected by Watering and Foliar Spray with Silica Nanoparticles

Abiotic stress caused by drought impairs plant growth and reduces yields. This study aimed to investigate the impact of silica nanoparticles (SiO2 NPs) through the adverse effects of drought on the growth, oxidative stress, and antioxidative response of pea ‘Respect’. Pea plants were grown in a greenhouse before being watered (100 ± 1 mL per pot) or foliar sprayed (ca. 14 ± 0.5 mL plant−1) with suspensions containing SiO2 NPs (0, 12.5 ppm, 25 ppm, and 50 ppm) and were exposed to drought stress for 10 days. Drought stress was created by maintaining 30% of the soil moisture while the control was 80%. The growth parameters of pea grown under drought stress conditions were improved by spraying or watering plants with SiO2 NPs (12.5, 25, and 50 ppm). At drought stress, peas treated with SiO2 NPs (50 ppm) increased their relative water content by 29%, specific leaf area by 17%, and decreased root/shoot ratio by 4% as compared to plant non-treated with SiO2 NPs. In addition, spraying or watering of SiO2 NPs increased peas tolerance to drought by increasing the activity of antioxidant enzymes at least three times including catalase, ascorbate peroxidase, glutathione reductase, and superoxide dismutase, as well as reducing hydrogen peroxide and lipid peroxidation in plant tissue. It was observed the increase in total phenolic compounds and non-enzymatic antioxidant activity (DPPH, ABTS, FRAP) in peas treated with SiO2 NPs under drought stress. The physiological response of peas to drought and the effects of SiO2 NPs studied in this experiment based on the use of the concentration of 50 ppm nanoparticles can protect peas from the damaging effects of drought and could help reduce global food shortages.

Crosstalk between phytohormones and secondary metabolites in the drought stress tolerance of crop plants: A review.

Drought stress negatively affects crop performance and weakens global food security. It triggers the activation of downstream pathways, mainly through phytohormones homeostasis and their signaling networks, which further initiate the biosynthesis of secondary metabolites (SMs). Roots sense drought stress, the signal travels to the above-ground tissues to induce systemic phytohormones signaling. The systemic signals further trigger the biosynthesis of SMs and stomatal closure to prevent water loss. SMs primarily scavenge reactive oxygen species (ROS) to protect plants from lipid peroxidation and also perform additional defense-related functions. Moreover, drought-induced volatile SMs can alert the plant tissues to perform drought stress mitigating functions in plants. Other phytohormone-induced stress responses include cell wall and cuticle thickening, root and leaf morphology alteration, and anatomical changes of roots, stems, and leaves, which in turn minimize the oxidative stress, water loss, and other adverse effects of drought. Exogenous applications of phytohormones and genetic engineering of phytohormones signaling and biosynthesis pathways mitigate the drought stress effects. Direct modulation of the SMs biosynthetic pathway genes or indirect via phytohormones' regulation provides drought tolerance. Thus, phytohormones and SMs play key roles in plant development under the drought stress environment in crop plants.

Nationwide temporal variability of droughts in the Kingdom of Eswatini: 1981–2018

For adequate mitigation and adaptation measures, it is essential to have detailed analysis of droughts patterns. This study determined the i) occurrence and severity of droughts ii) drought recurrence frequencies and iii) drought trends across different agro-ecological zones in the Kingdom of Eswatini for the period 1981 to 2018. A Standardised Precipitation Index (SPI) computed from long-term precipitation data measured from six meteorological stations was used to determine drought occurrence and severity. Python software (Version 3.6) was applied on the SPI values to predict the recurrence of drought events over time in years. The SPI showed that in the Highveld, 42% of the droughts were moderate, 32% were severe and the remaining 26%, which all occurred post 1980 were extreme (SPI -2.34 to -2.82). The Middleveld had an even proportion of drought categories (29–35%). The Lowveld recorded 62% of moderate, 8% severe and 30% extreme droughts of which 70% occurred post 2000. Moderate droughts were found to recur every 4–5 years while extreme droughts are expected every 13–21 years. These findings are essential for mitigation and adaptation measures geared towards the adverse effects of droughts.

Stress physiology and metabolism in hybrid rice.III. Puddling and soil compaction regulate water status and internal metabolism during drought

ABSTRACT Global water crisis, resulting from climate change, has become a prime concern for agricultural production. Our objectives were to determine the impact of puddling and soil compactionon drought tolerance, metabolism and antioxidative enzymes affecting growth of hybrid rice (Oryza sativa L.) under drought conditions. Accordingly, an experiment with three treatments, viz., puddled, compact, and control soils was conducted in pots using a completely randomized design with three replications. Both puddling and soil compaction reduced the adverse effects of drought on physiological traits. The positive effects of water stagnation because of physical modifications of soil, on drought tolerance traits and antioxidative enzymes during water stress, caused 1.2 to 2-fold increase in penetration resistance of physically modified soils and concomitantly reduced 3 to 6-fold water infiltration rate thereof. Puddling and soil compaction enabled plants maintain higher water potential than the control plants under drought conditions. Such plant conditions in puddled and compact soils caused low levels of proline and sugar, followed by higher levels of starch and protein than the control plants. Drought increased superoxide dismutase activity 2 to 2.4-fold, catalase 2 to 2.2-fold, ascorbate peroxidase 1.7 to 2-fold, and lipid peroxidase 2.3 to 3.6-fold. Adaptation to drought was apparently attributable to the cross-talk of drought event with plant metabolism, giving rise to the evolution of protective metabolic strategies. Thus, the increased water availability, through decreased water infiltration caused by puddling and soil compaction, is an important agronomic intervention for the maintenance of physiological activities andgrowth of rice under drought conditions.

Development of a Non-Linear Integrated Drought Index (NDI) for Managing Drought and Water Resources Forecasting in the Upper Tana River Basin-Kenya

This article uses the non-linear integrated drought index (NDI) for managing drought and water resources forecasting in a tropical river basin. The NDI was formulated using principal component analysis (PCA). The NDI used hydro-meteorological data and forecasted using recursive multi-step neural networks. In this article, drought forecasting and projection is adopted for planning ahead for mitigation and for the adaptation of adverse effects of droughts and food insecurity in the river basin. Results that forecasting ability of NDI model using ANNs decreased with increase in lead time. The formulated NDI as a tool for projecting into the future.

Stress physiology and metabolism in hybrid rice. I. Organic manures improve physical soil characteristics and drought tolerance

ABSTRACTThe present era is witnessing a serious water crisis affecting rice (Oryza sativa) productivity adversely. Therefore, with the objective of minimizing crop failure under limited water supply the effects of organic manures were compared with inorganic fertilizer for changes in soil physical characteristics, morpho-physiological traits and drought resistance of hybrid rice NDRH-2. Accordingly, one level each of green manure and compost (7.5 t ha−1) was applied supplemented with chemical fertilizers to bring them nutritionally at par with inorganic fertilizer treatment. Organic manures minimized the adverse effect of drought on plant height during a 10-day soil-drying cycle. Organically fertilized treatments enhanced plant sustenance by 4-7 days during drought compared with that fertilized inorganically. Sustenance enhancement was probably due to increased soil moisture-holding capacity [26% to 27.4% in organically fertilized soil (OFS) against 22.2% in inorganically fertilized soil (IFS)] because of decreased soil bulk density (1.20g mL−1 OFS against 1.42 IFS) and soil penetration resistance (500 to 560 kPa OFS against 800 kPa IFS). The organic manures significantly increased leaf water potential (−16 to −18.5 bars OFS against −25 bars IFS), relative water content (84 to 85% OFS against 78% IFS), cell viability (OD 0.290 to 0.352 OFS against 0.165 IFS), membrane stability (83 to 87% OFS against 75%IFS), chlorophyll (10.06 mg g−1 dry weight OFS against 9.42 IFS) and reduced leaf injury (score 3 to 4 OFS against 5 IFS) causedby drought. Hence, farmers living in drought-prone regions, are advised to practice organic farming using organic manures for a successful rice crop in event of scanty rainfall.

Disentangling how climate change can affect an aquatic food web by combining multiple experimental approaches.

Predicting the biological effects of climate change presents major challenges due to the interplay of potential biotic and abiotic mechanisms. Climate change can create unexpected outcomes by altering species interactions, and uncertainty over the ability of species to develop in situ tolerance or track environmental change further hampers meaningful predictions. As multiple climatic variables shift in concert, their potential interactions further complicate ecosystem responses. Despite awareness of these complexities, we still lack controlled experiments that manipulate multiple climatic stressors, species interactions, and prior exposure of species to future climatic conditions. Particularly studies that address how changes in water availability interact with other climatic stressors to affect aquatic ecosystems are still rare. Using aquatic insect communities of Neotropical tank bromeliads, we combined controlled manipulations of drought length and species interactions with a space-for-time transplant (lower elevations represent future climate) and a common garden approach. Manipulating drought length and experiment elevation revealed that adverse effects of drought were amplified at the warmer location, highlighting the potential of climatic stressors to synergistically affect communities. Manipulating the presence of omnivorous tipulid larvae showed that negative interactions from tipulids, presumably from predation, arose under drought, and were stronger at the warmer location, stressing the importance of species interactions in mediating community responses to climate change. The common garden treatments revealed that prior community exposure to potential future climatic conditions did not affect the outcome. In this powerful experiment, we demonstrated how complexities arise from the interplay of biotic and abiotic mechanisms of climate change. We stress that single species can steer ecological outcomes, and suggest that focusing on such disproportionately influential species may improve attempts at making meaningful predictions of climate change impacts on food webs.

Mitigation of PEG-induced drought stress in rapeseed (Brassica rapa L.) by exogenous application of osmolytes

Abstract Considering the adverse effect of drought on plants growth, development and physiology, we studied the protective role of three osmolytes, proline (Pro), glycine betaine (GB) and trehalose (Tre) for the mitigation the adversity of drought on rapeseed (Brassica rapa L. cv. BARI Sharisha-15) seedlings. The experiment consisted of eight treatments viz. control, Pro (0.5 mM), GB (0.5 mM), Tre (0.5 mM), Drought (20% Polyethylene glycol, D), Pro + D, GB + D and Tre + D. Reduced plant height, seedling fresh and dry biomass, relative water content (RWC) of leaf and chlorophyll (chl) contents were observed due to drought stress with increased levels of endogenous Pro, GB, and Tre. Drought stress also induced oxidative stress, manifested by the overgeneration of toxic superoxide (O2•−) radicals, increased hydrogen peroxide (H2O2), malondialdehyde (MDA), and methylglyoxal (MG) content, as well as impaired antioxidant defense and redox balance. However, pretreatment with Pro, GB and Tre upregulated the antioxidant defense mechanisms and reduced oxidative damage by reducing MDA, H2O2 and MG contents. Moreover, increased the glutathione (GSH), and decreased oxidized glutathione (GSSG) levels, finally improved the redox balance. In addition, exogenously applied osmolytes improved the chl contents and water balance, which improved the rapeseed seedlings development. Among the three osmolytes studied, Pro performed best in alleviating drought stress in rapeseed at the early seedling stage.

Exploring improvements to the design of an operational seasonal forage scarcity index from NDVI time series for livestock insurance in East Africa

Recurrent drought represents a major threat in arid and semi-arid regions of East Africa where pastoralists depend on their livestock for subsistence. In Kenya and southern Ethiopia, an existing satellite-based index insurance scheme aims to protect pastoralists against the adverse effects of drought. Under that scheme, payouts are made based on an area-aggregated seasonal forage scarcity index derived from remotely-sensed Normalized Difference Vegetation Index (NDVI). NDVI values are directly averaged per unit areas of insurance (UAI), which are based on administrative borders but take into limited account the ecological variability within the unit. The choice of administrative boundaries at the onset of the analysis may negatively impact the performance of the product. Our study explores an alternative index design based on an ecological stratification of the study area. First, we performed an unsupervised classification of NDVI time series from the Moderate Resolution Imaging Spectroradiometer (MODIS) to group pixels with similar temporal NDVI trajectories. Next, we used average NDVI profiles and ancillary data to discard areas deemed insignificant for forage production. We then transformed NDVI values into z-scores to assess how each pixel relates to the multi-year distribution of NDVI values per class and season. In the final step, we calculated the alternative forage scarcity index, which is the percentage of pixels with anomalously low NDVI values per season and UAI (i.e. z-score ≤ −1.0). To evaluate its performance, we compared unit-level results for both the original and alternative designs against spatially-aggregated monthly household survey data on livestock mortality from 16 sample sites corresponding to eight administrative units within the study area. Besides performing better in predicting livestock mortality (i.e. increases of 53% and 39% in correlation coefficients as measured by Pearson’s r and Spearman’s ρ, respectively) and strengthening the ecological significance of the index, the proposed design has a number of other advantages: 1) the index is calculated using a much larger statistical basis, 2) it allows for analysis of forage conditions at sub-unit level, and 3) it offers a more flexible structure for payout calculation. These advantages could be of particular relevance for expanding the index-insurance scheme to agro-pastoral regions characterized by more heterogeneous landscapes. Finally, we propose to consider using this approach to better account for the ecological variability of rangelands in other NDVI-based early warning and monitoring systems.

Integrated effect of planting dates and irrigation regimes on morpho-physiological response, forage yield and quality, and water use efficiency of clitoria (Clitoria ternatea L.) in arid region

ABSTRACTA 2-year field experiment (2015/2016) was conducted on clitoria planted on May 20 as early (PE) and June 20 as late (PL) under 100% = I100%, 80% = I80% and 60% = I60% of allowable soil moisture depletion (ASMD). The objective was to investigate the complementary effect of planting date and deficit irrigation on morpho-physiological responses, forage quantity and quality, and water use efficiency (WUE) of clitoria. Early planting date (PE) significantly improved almost all attributes. Clitoria plants exposed to (I100% or 80%) had higher almost parameters except for leaf/stem ratio (LSR), protein, and WUE in both seasons. Higher cumulative dry forage yield CDFY (6.5 and 6.4 t ha−1) and cumulative protein yield CPY (1.4 and 1.2 t ha−1) resulted from I80% and I100% whereas, highest WUE (1.8 and 1.6 kg m−3) from I60% in both the seasons, respectively. Clitoria planted early and irrigated with I100% or 80% had higher morpho-physiological responses and yields in both cuts of both seasons. Therefore, the adverse effects of drought can be diminished by planting early (PE) and watering with (I100% or 80%), particularly under limited water and could be suggested as a non-monetary practice for upgrade the drought tolerance in clitoria and maximizing yield and quality in arid environments.