Salt tolerance analysis of chickpea,faba bean and durum wheat varieties: II. Durum wheat

Seven varieties of durum wheat (Triticum turgidum), provided by ICARDA, were tested in a greenhouse experiment for their salt tolerance. Afterwards two varieties, differing in salt tolerance, were irrigated with waters of three different salinity levels in a lysimeter experiment to analyse their salt tolerance.The characteristics of the salt tolerant variety compared to the salt sensitive variety are:

• -a shorter growing season and earlier senescence;
• -a higher pre-dawn leaf water potential;
• -a stronger osmotic adjustment;
• -a better maintenance of the number of productive stems per plant.

Salt tolerance of durum wheat corresponds with drought tolerance because the tolerance is caused by earlier senescence and stronger osmotic adjustment, both reducing the transpiration of the plant.     

Salinity effect on grain quality of two durum wheat varieties differing in salt tolerance

The salt tolerant variety Cham-1, created by ICARDA, showed a higher grain yield than the less salt tolerant landrace Haurani, but the main parameters for the pasta quality declined considerably. Salinity had a slight positive effect on the grain quality of the Cham-1 variety, whereas the Haurani variety showed no salinity effect on grain quality. A decrease in ash content corresponded with an increase in water use efficiency. The relationship between ash content and water use efficiency may be useful for selecting varieties with high water efficiency under saline conditions.     

Response to soil salinity of two chickpea varieties differing in drought tolerance

Two chickpea varieties, differing in drought tolerance, were grown in lysimeters filled with clay, and were irrigated with waters of three different salinity levels. Under non-saline conditions, both varieties, slightly differing in pre-dawn leaf water potential during the growth period, gave almost the same yield.Salinity had a slight effect on the leaf water potential and the osmotic adjustment. Both were slightly higher for the drought tolerant variety, but much lower in comparison with sugar beet, tomato and lentil. The drought tolerant variety showed an earlier senescence in leaf and dry matter development and flowering which were accelerated by salinity. The drought sensitive variety, however, showed under slightly saline conditions (EC_e=2.5 dS/m) from 135 days after sowing onwards a different behaviour by the growth of new leaves and flowers, a delay in senescence, leading to the same yield as under non-saline conditions. Under saline conditions (EC_e=3.8 dS/m) the drought sensitive variety showed the same yield reduction of about 70% as the drought tolerant variety.     

Growth of faba bean (Vicia faba L.) as influenced by irrigation water salinity and time of salinization

A greenhouse study was conducted to investigate the response of faba bean (Vicia faba L.) to water salinity applied at different times of salinization. Faba beans were grown on loamy sand in pots and irrigated daily with modified half-strength Hoagland's solution. Salinization of the nutrient solution with NaCI and CaCl₂ (2:1 molar ratio) provided four treatment solutions with electrical conductivities of 2, 6, 10 and 14 dS m⁻¹ and was imposed on the tenth day from planting, and continued until day 30 (T1), from day 30 until day 50 (T2) and from day 50 to day 70 (T3) using a randomized block factorial design with five replications. The results indicated that faba bean was more sensitive to salinity during the vegetative stage and less sensitive at later stages. Water salinity significantly reduced the grain yield and grain number but did not affect grain weight. Vegetative growth decreased significantly by salinity stress during the three salinization periods but was more serious at the first stage.     

Varietal differences in the response of durum wheat (Triticum turgidum L. var. durum) to irrigation strategies in a semi-arid region of Algeria

The response of three durum wheat cultivars (C: Chen’s, V: Vitron, W: Waha) to irrigation was studied during 4 years in semi-arid Algeria (Chlef). The four treatments were NI (unirrigated), EI (early irrigation, up to heading), LI (late irrigation, from heading) and FI (full irrigation, over the entire season). FI increased rainfed grain yield (1,300 kg ha⁻¹) by 270%, EI by 107%, and LI by 67%. The variety × irrigation interaction was significant each year. Under irrigation, cv. Vitron was generally the most productive cultivar while in rainfed conditions cv. Waha always resulted in the highest grain yield. Grain yield increased exponentially with seasonal evapotranspiration (r ² = 0.741) and harvest index (r ² = 0.873). Water use efficiency for grain ranged from 4.6–5.3 kg ha⁻¹ mm⁻¹ (NI) to 9.6–10.8 kg ha⁻¹ mm⁻¹ (FI) as a function of cultivar and irrigation, cv. Vitron and cv. Waha (full irrigation) and cv. Waha (rainfed) being the most efficient cultivars. According to the evaporation pan method, the seasonal crop coefficient (K _c) values for the three cultivars were 0.64 (V), 0.62 (W) and 0.54 (C). The corresponding peak K _c values were 1.0, 0.97 and 0.89, respectively. K _c was closely related to leaf area index (LAI) and specific logarithmic relationships were calculated for each cultivar. Irrigation scheduling should be adapted to the type of cultivar in relation to its potential yield and LAI development pattern.     

Yield and water productivity of five chickpea varieties under supplemental irrigation in contrasting years

Chickpea (Cicer arietinum L.) is one of the most important pulse crops in the world, cultivated on a wide range of environments. In Mediterranean regions, it is traditionally grown as a spring-sown rainfed crop, very dependent on rainfall. In this situation, supplemental irrigation can improve significantly the crop yield. The objective of this study was to evaluate the improvement on chickpea crop yield and water productivity (WP) of five chickpea varieties with supplemental irrigation, in the Mediterranean conditions, with both dry and wet years. Field tests were carried out over two cropping seasons, in Southern Portugal, using three kabuli-type and two desi-type chickpea varieties and four irrigation treatments, corresponding to 100, 50, 25 % of crop irrigation requirements (IR) and rainfed. The results show that all chickpea varieties responded to supplemental irrigation with the increase in grain and biomass yield. However, the magnitude of individual chickpea response depends on the year and the genotype. In 2009, a dry year, the highest WP values were attained at the 50 % IR treatment, whereas in 2010, a wet year, it was the rainfed treatment that showed the highest WP values. The Elixir variety showed the best grain yields and water productivity.     

Yield and water-production functions of two durum wheat cultivars grown under different irrigation and nitrogen regimes

Wheat (Triticum durum L.) yields in the semi-arid regions are limited by inadequate water supply late in the cropping season. Planning suitable irrigation strategy and nitrogen fertilization with the appropriate crop phenology will produce optimum grain yields. A 3-year experiment was conducted on deep, fairly drained clay soil, at Tal Amara Research Station in the central Bekaa Valley of Lebanon to investigate the response of durum wheat to supplemental irrigation (IRR) and nitrogen rate (NR). Three water supply levels (rainfed and two treatments irrigated at half and full soil water deficit) were coupled with three N fertilization rates (100, 150 and 200 kg N ha⁻¹) and two cultivars (Waha and Haurani) under the same cropping practices (sowing date, seeding rate, row space and seeding depth). Averaged across N treatments and years, rainfed treatment yielded 3.49 Mg ha⁻¹ and it was 25% and 28% less than half and full irrigation treatments, respectively, for Waha, while for Haurani the rainfed treatment yielded 3.21 Mg ha⁻¹, and it was 18% and 22% less than half and full irrigation, respectively. On the other hand, N fertilization of 150 and 200 kg N ha⁻¹ increased grain yield in Waha by 12% and 16%, respectively, in comparison with N fertilization of 100 kg N ha⁻¹, while for cultivar Haurani the increases were 24% and 38%, respectively. Regardless of cultivar, results showed that supplemental irrigation significantly increased grain number per square meter and grain weight with respect to the rainfed treatment, while nitrogen fertilization was observed to have significant effects only on grain number per square meter. Moreover, results showed that grain yield for cultivar Haurani was less affected by supplemental irrigation and more affected by nitrogen fertilization than cultivar Waha in all years. However, cultivar effects were of lower magnitude compared with those of irrigation and nitrogen. We conclude that optimum yield was produced for both cultivars at 50% of soil water deficit as supplemental irrigation and N rate of 150 kg N ha⁻¹. However, Harvest index (HI) and water use efficiency (WUE) in both cultivars were not significantly affected neither by supplemental irrigation nor by nitrogen rate. Evapotranspiration (ET) of rainfed wheat ranged from 300 to 400 mm, while irrigated wheat had seasonal ET ranging from 450 to 650 mm. On the other hand, irrigation treatments significantly affected ET after normalizing for vapor pressure deficit (ET/VPD) during the growing season. Supplemental irrigation at 50% and 100% of soil water deficit had approximately 26 and 52 mm mbar⁻¹ more ET/VPD, respectively, than those grown under rainfed conditions.     

Salt tolerance of crops according to three classification methods and examination of some hypothesis about salt tolerance

This publication is a complement to a previous publication on salt tolerance classification, using the observations of a long-term experiment on the use of saline water. Three classification methods were compared, based, respectively, on the electrical conductivity of the saturated paste extract, the relative evapotranspiration deficit and the water stress day index. Among the eight crops grown during the experiment, broadbean, soybean and tomato were clearly distinguished by the methods based on the relative evapotranspiration deficit and the water stress day index as more sensitive then durum wheat, maize, potato, sugar beet and sunflower. Their greater sensitivity may be explained by the salt sensitivity of rhizobium bacteria affecting the nitrogen supply, by the degree of osmotic adjustment or by the prolongation of the flowering period.     

Water uptake, water use efficiency, plant growth and ionic balance of wheat, barley, canola and chickpea plants on a sodic vertosol with variable subsoil NaCl salinity

Salinity in topsoil and subsoil is one of the major abiotic environmental stresses to crop production. To investigate the comparative tolerance ability of wheat, barley, canola and chickpea to subsoil NaCl salinity and its impact on water uptake, water use efficiency, plant growth and ionic balance, a pot experiment was conducted on a heavy texture soil (sodic vertosol) having 20 ESP (exchangeable sodium percentage), 3.5 dS/m EC_e and 400 mg/kg Cl with additional NaCl applied in subsoil at 500, 1000, 1500 and 2000 mg/kg soil. Plants were harvested 40 days after sowing and assessed for different parameters. Increasing levels of subsoil NaCl salinity had significant depressing effect on shoot and root biomass, root/shoot ratio, water uptake and water use efficiency (shoot biomass production with a unit amount of applied water), leaves K:Na ratio and Ca:Na ratio of all the four species, but the magnitude of effect varied considerably among the species. Chickpea was affected most followed by wheat, barley and canola at the highest level of subsoil NaCl salinity. There was 64%, 49%, 37% and 34% reduction in shoot dry weight of chickpea, wheat, barley and canola respectively by highest subsoil salinity. Similarly water uptake declined by 61%, 36%, 31% and 26% respectively in chickpea, wheat, barley and canola. Water use efficiency of four species was in order of barley > canola > wheat > chickpeas on this sodic vertosol. The cumulative effects of reduced osmotic potential of soil solution, ion toxicity (high concentrations of Cl and Na) in soil/plants and ionic imbalance (reduced K:Na and Ca:Na ratio) within plant system under increased subsoil NaCl salinity contributed to reduce water uptake and plant growth in all the four crops, and the effects were more severe in chickpeas. Wheat despite having considerably lower Na and Cl in their leaves suffered greatly in plant growth and water uptake compared with barley and canola indicating better tolerance ability of barley and canola to high Cl and Na build up at tissue level. Results suggest chickpea to be the most sensitive to subsoil NaCl salinity. The growing of comparatively tolerant species like barley and canola may be the better option for sustaining crop production and higher water use efficiency on sodic vertosols with high subsoil NaCl salinity.     

Adapting PILOTE model for water and yield management under direct seeding system: The case of corn and durum wheat in a Mediterranean context

Crop models are useful tools for integrating knowledge of biophysical processes governing the plant-soil-atmosphere system. But few of them are easily usable for water and yield management especially under specific cropping systems such as direct seeding. Direct seeding into mulch (DSM) is an alternative for conventional tillage (CT). DSM modifies soil properties and creates a different microclimate from CT. So that, we should consequently consider these new conditions to develop or to adapt models. The aim of this study was to calibrate and validate the PILOTE [Mailhol, J.C., Olufayo, A.A., Ruelle, P., 1997. Sorghum and sunflower evapotranspiration and yield from simulated leaf area index. Agric. Water Manag. 35, 167-182; Mailhol, J.C., Zaïri A., Slatni A., Ben Nouma, B., El Amami, H., 2004. Analysis of irrigation systems and irrigation strategies for durum wheat in Tunisia. Agric. Water Manag. 70, 19-37], an operative crop model based on the leaf area index (LAI) simulation, for corn and durum wheat in both DSM and CT systems in Mediterranean climate. In DSM case, simple model modifications were proposed. This modified PILOTE version accounts for mulch and its impact on soil evaporation. In addition root progression was modified to account for lower soil temperatures in DSM for winter crops. PILOTE was calibrated and validated against field data collected from a 7-year trial at the experimental station of Lavalette (SE of France). Results indicated that PILOTE satisfactorily simulates LAI, soil water reserve (SWR), grain yield, and dry matter yield in both systems. The minimum coefficient of efficiency for SWR was 0.90. This new version of PILOTE can thus be used to manage water and yield under CT and DSM systems in Mediterranean climate.     

Salt tolerance in the wild relatives of the cultivated tomato: responses of Solanum pennellii to high salinity

Summary The cultivated tomato Lycopersicon esculentum, cultivar Rheinlands Ruhm, and the wild species Solanum pennellii accession Atico, were compared with respect to their salt tolerance. The wild species was found to be more salt tolerant than the cultivated tomato. In contrast to L. esculentum plants, the growth of the wild species was not impaired by the high salinity (Table 1), although the latter accumulated more Cl^– and Na⁺ ions and its K⁺ level decreased under salinity (Tables 3, 4, 5). The smaller increase in water deficit under salinity in the wild species, probably resulted from its higher accumulation of ions (Table 2).     

Nitrogen balance and irrigation water productivity for corn, sorghum and durum wheat under direct seeding into mulch when compared with conventional tillage in the southeastern France

Direct seeding into mulch (DSM) reduces soil evaporation. Therefore, DSM can decrease the crop water demand. Furthermore, DSM provides a favorable food source for soil microorganisms that can enhance the degradation of organic matter and improve nitrogen (N) availability for crops. Nowadays, a major challenge in irrigation is to increase irrigation water productivity (WP). This study assessed the impact of DSM on the N balance and WP according to experimental results compared with conventional tillage (CT). The results showed that DSM could mitigate N losses and improve WP for corn and sorghum. Because of field experimental limitations, PILOTE, an operational model, was employed to test the hypothesis that DSM can be more efficient in water use. PILOTE was adapted and then calibrated and validated in the same experimental station. Taking into account the cover crop season, the model simulated the irrigation amount for a corn crop with a target yield of 14 t/ha during the long climatic series of 1991–2007. The results showed a WP increase from 77 with CT to 102 kg/mm with DSM. DSM can improve WP and save a water application depth of 40 mm compared to CT, which is interesting in a context with water scarcity.     

Canopy-air temperature differentials,water use and yield of chickpea in a semi-arid environment

Summary Stress degree days (SDD) and canopy-air temperature differential summation procedures were used to quantify the response of crops of chickpea (Cicer arietinum L.) to soil water availability and atmospheric demand over a four year period on a deep and medium-deep Vertisol in India using different irrigation treatments and planting dates. Canopy temperatures measured between 13.00–14.00 h provided a good index of the daily mean canopy temperature. Differences in the diurnal variation in the canopy-air temperature differentials between irrigated and non-irrigated chickpea reflected clearly the differential response of the crop to soil water availability. Total water use of chickpea decreased with increasing SDD. Data pooled over three growing seasons showed a close relationship between SDD and yield of chickpea. Calculated water stress index (WSI) which includes the vapor pressure deficit term showed a similar relationship with yield to that with SDD.Approved for publication as ICRISAT Journal Article 580(Via Paris)     

Effects of transient subsurface waterlogging on root growth, plant biomass and yield of chickpea

Root growth and proliferation are important for achieving the yield potential of chickpea in soils prone to waterlogging. Root growth characteristics and seed yield of the desi cultivar Rupali and the kabuli cultivar Almaz that differ in seed size and early vigour were investigated under well-drained and transiently-waterlogged conditions in glass-walled root boxes in a controlled-temperature glasshouse. Rooting parameters and detailed measurements of root growth and proliferation were made at 2-day intervals using a root mapping technique and by sampling the roots from the soil 14 days after the transient waterlogging ended. Although the roots of the kabuli cultivar Almaz had greater dry matter and length than the desi cultivar Rupali, the subsurface waterlogging promptly stopped the root growth of both genotypes. Root dry matter in both types of chickpea was reduced by two-thirds, 14 days after the cessation of the 12-day waterlogging treatment. The reduction resulted from an inhibition in root growth and proliferation, which led to a lower root length density down the soil profile, particularly in the top 0.6 m of the waterlogged plants. While root length and root dry matter was higher in the kabuli cultivar Almaz than in the desi cultivar Rupali after waterlogging, they were not associated with a greater above-ground dry matter or seed yield at maturity. The transient waterlogging reduced the seed yield by 54% in the kabuli cultivar Almaz and by 44% in the desi cultivar Rupali. The reduction in seed yield in the kabuli cultivar Almaz resulted from 50% decline in the number of seeds per pod while in the desi cultivar Rupali it was a consequence of less pods and seeds per pod. Subsurface waterlogging changed the rooting pattern in chickpea, inhibiting root branching and the growth of the tap root and severely reducing the growth of root branches. The release from the waterlogging induced the production of new roots rather than regrowth of existing roots.     

An agronomic, economic and behavioral analysis of N application to cotton and wheat in post-Soviet Uzbekistan

Cotton and winter wheat play a vital role in Uzbek agriculture: the first crop is a vital component of the national export revenues, while the latter is key in achieving independence from grain imports. Due to these strategic roles in the national economy, both crops are part of the state procurement system and, hence, are subject to strict regulations imposed to ensure budget revenues and self-sufficiency. However, many factors cause the divergence of crop yields from their technically maximum levels. We analyzed those factors, which hamper achieving the optimum response to fertilizer applications. In a stepwise procedure, we (i) reviewed the technical and financial optimum yield responses of cotton and winter wheat production to fertilizer applications and (ii) analyzed the changes of fertilizer-to-product price ratios to shed light on the agronomic and economic performance of cotton and wheat in the post-Soviet agricultural system of Uzbekistan. The analysis combined data from long-term, historical yield and fertilizer responses, agronomic N-fertilizer response experiments, and socio-economic farm surveys. Quadratic yield-response functions were used to derive economic and technical optimum rates of N-fertilizer applications. Based on the parameterized function and fertilizer-to-product price ratios observed for 1996-2003, we analyzed the difference between recommended fertilization and economic optimum application rates. Results showed that under the state procurement system, Uzbek farmers may not necessarily tend to maximize the profits from their cotton and wheat production. The level of subsidies and the differential crop support by the state induce farmers to follow the official fertilizer recommendations to ensure that they fulfill the production targets even if it implies higher production costs. The present gaps between the officially recorded yields and those technically achievable given the agro-ecological conditions in Uzbekistan cannot be narrowed by only improving N-fertilizer management. It would require additional efforts to improve cotton and wheat yields.     

Salinity effect on crop development and yield,analysis of salt tolerance according to several classification methods

The publication is a synthesis of previous publications on the results of a long-term lysimeter experiment. From 1989 to 1998, the experimental variables were soil salinity and soil type, from 1999 onwards, soil salinity and crop variety. The plant was studied during the whole growing period by measuring the saline stress and analyzing its effect on leaf area and dry matter development and on crop yield. Salinity affected the pre-dawn leaf water potential, stomatal conductance, evapotranspiration, leaf area and yield.The following criteria were used for crop salt tolerance classification: soil salinity, evapotranspiration deficit, water stress day index. The classification according to soil salinity distinguished the salt tolerant group of sugar beet and wheat, the moderately salt sensitive group comprising broadbean, maize, potato, soybean, sunflower and tomato, and the salt sensitive group of chickpea and lentil. The results for the salt tolerant and the moderately salt sensitive groups correspond with the classification of Maas and Hoffman, excepted for soybean.The evapotranspiration deficit criterion was used, because for certain crops the relation between yield and evapotranspiration remains the same in case of drought and salinity. This criterion, however, did not appear useful for salt tolerance classification.The water stress day index, based on the pre-dawn leaf water potential, distinguished a tolerant group, comprising sugar beet, wheat, maize, sunflower and potato, and a sensitive group, comprising tomato, soybean, broadbean, chickpea and lentil. The classification corresponds with a difference in water use efficiency. The tolerant crops show a more or less constant water use efficiency. The sensitive crops show a decrease of the water use efficiency with increasing salinity, as their yield decreases stronger than the evapotranspiration. No correlation could be found between osmotic adjustment, leaf area and yield reduction. As the flowering period is a sensitive period for grain and fruit formation and the sensitive crops are all of indeterminate flowering, their longer flowering period could be a cause of their greater sensitivity.The tolerant group according to water stress day index can be divided according to soil salinity in a salt tolerant group of sugar beet and wheat and a moderately sensitive group, comprising maize, sunflower and potato. The difference in classification can be attributed to the difference in evaporative demand during the growing period.The sensitive group according to water stress day index can be divided according to soil salinity in a moderately sensitive group, comprising tomato, soybean and broadbean, and a salt sensitive group of chickpea and lentil. The difference in classification can be attributed to the greater salt sensitivity of the symbiosis between rhizobia and grain legume in the case of chickpea and lentil.     

Leaching requirement for salinity control I. Wheat,sorghum, and lettuce

Crop productivity and water use efficiency when saline irrigation water is used are highest when efficient irrigation systems are managed to meet the crop's leaching requirement. The objective of this experiment was to establish the leaching requirement. The objective of this experiment was to establish the leaching requirements for frequently irrigated wheat, grain sorghum, and head lettuce. The 4-year study in field plots consisted of six replicated leaching fraction treatments. The plots were pulse-irrigated daily with water having a total dissolved salts concentration of 1350 mg/l.The leaching requirements are 0.08 for wheat and sorghum, and 0.26 for lettuce. The respective evapotranspiration during each crop's growing season coincident with the leaching requirements was 440, 550, and 245 mm. A pan factor of 0.7 was consistent among these three crops at their respective leaching requirements. With daily irrigation, 90% of the crop's water uptake occurred above a soil depth of 0.6 m, independent of leaching fraction.     

Agronomic and socio-economic analysis of water management techniques for dry season cultivation of common bean in Malawi

A study was carried out in Malawi to compare agronomic and socio-economic aspects of different water management practices for two advanced bean lines. Four irrigation technologies and one control were studied in Chingale Area Development Program in Zomba District in southern Malawi. The technologies encompassed motorized pumps (MP), treadle pumps (TP), water cans, gravity-fed surface irrigation (GR) and a non-irrigated practice that used residual moisture. The study found that technologies that used <2 labour hours m^?3 were appropriate for such small-scale irrigation systems. The aggregated bean production labour cost and labourday thresholds were $893 ha^?1 and 2,978 LD ha^?1, respectively. An irrigation supply in the range of 7,000–10,000 m³ ha^?1 for the TP, MP and GR would be adequate. Assuming 20 irrigations season^?1, 400–600 m³ irrigation^?1 would be adequate, supplying 40–60 mm every 5–7 days. The study found that poor small-scale farmers in Malawi, particularly those using MPs, need fuel subsidies in order to offset operational costs. Basing on the findings in the study, we recommend further research on several bean lines in different agro-ecologies of Malawi using technologies that showed high yields, low labour efficiency and high water use productivity.     

Water use,water-use efficiency and yield of dryland chickpea as influenced by P fertilization,stored soil water and crop season rainfall

Dryland chickpea is grown on stored water in the soil profile and with limited crop season rainfall (CSR). In a field experiment, carried out for 3 years on silty loam soil, water extraction pattern, water use and its efficiency by chickpea in relation to P application, stored soil water and crop season rainfall have been investigated. Stored soil water varied from 182 to 246 mm in a meter profile and the CSR varied from 72 to 184 mm.Response of P application increased with increasing initial water storage in the soil profile. The first 60–100 days of crop growth appeared to be the most critical. Water stress during this period severely affected the yield. Rainfall after 100 days did not appear to have been fully utilized by the crop, especially when the crop had already suffered from water stress between 60 and 100 days. Compared with the control, P application increased yield, water use and water-use efficiency. Soil water depletion was 25% greater for the fertilized crop than for the unfertilized crop.