Exogenous Application of Abscisic Acid Improves Cold Tolerance in Chickpea (Cicer arietinum L.)

Chickpea suffers cold stress (<10 °C) damage especially during reproductive phase resulting in the abortion of flowers and pods, poor pod set, and reduction in seed yield and seed quality. One of the ways in modifying cold tolerance involves exogenous treatment of the plants with chemicals having established role in cold tolerance. In the present study, the chickpea plants growing under optimum temperature conditions (28/12 °C, as average maximum and minimum temperature) were subjected to cold conditions of the field (10–12/2–4 °C; day/night as average maximum and minimum temperature) at the bud stage. Prior to exposure, these plants were treated exogenously with 10 μm abscisic acid (ABA) and thereafter again after 1 week of exposure. The stress injury measured in terms of increase in electrolyte leakage, decrease in 2,3,5-triphenyl tetrazolium chloride reduction %, relative leaf water content and chlorophyll content was observed to be significantly mitigated in ABA-applied plants. A greater pollen viability, pollen germination, flower retention and pod set were noticed in ABA-treated plants compared with stressed plants. The seed yield showed considerable improvement in the plants treated with ABA relative to the stressed plants that was attributed to the increase in seed weight, greater number of single seeded pods and reduction in number of infertile pods. The oxidative damage measured as thiobarbituric acid-reactive substances was lesser in ABA-treated plants that was associated with greater activities of superoxide dismutase, catalase, ascorbate peroxidase, ascorbic acid, glutathione and proline in these plants. It was concluded that cold stress effects were partly overcome by ABA treatment because of the improvement in water status of the leaves as well as the reduction in oxidative damage.     

Cold Stress Injury during the Pod-Filling Phase in Chickpea (Cicer arietinum L.): Effects on Quantitative and Qualitative Components of Seeds

Chilling stress (<10 °C) is detrimental for chickpea, especially at the reproductive phase and leads to abortion of flowers, pods and impaired seed filling, causing severe reduction in yield. The information on the effects of low temperature during different pod-filling stages on quality and quantity of developing seeds is lacking in chickpea and hence this study. In this study, chickpea plants growing under warm conditions of the glasshouse were subjected to cold conditions of the field at the two stages, (a) early pod-filling and (b) late pod-filling, and subsequently analysed for stress injury in terms of electrolyte leakage (EL), 2,3,5-triphenyl tetrazolium chloride reduction, relative leaf water content and total chlorophyll content in the leaves of control and cold-stressed plants. Cold stress caused elevation of EL but reduced all the other parameters. Sucrose content decreased significantly in the leaves of cold-stressed plants. The differences between the effects of stress at two stages on the total plant dry weight were small and insignificant. The seed growth rate, seed fill duration, seed number, and average seed weight and size decreased greatly in the plants cold-stressed at the late pod-filling stage than those stressed at the early pod-filling stage. Greater reduction was observed in starch, proteins, soluble sugars, fat, crude fibre and storage protein fractions in the seeds of the plants cold-stressed at the late pod-filling stage. This coincided with a larger decrease in sucrose content, the activities of sucrose synthase, invertase and starch synthase observed at this stage. The germination and growth potential were, however, inhibited to a greater extent in seeds of plants stressed at the early pod-filling stage.     

Evaluation of Yield Criteria for Drought and Heat Resistance in Chickpea (Cicer arietinum L.)

The chickpea (Cicer arietinum L.) is usually grown under rainfed, rather than irrigated conditions, where drought accompanied by heat stress is a major growth constraint. The aim of this study was to select chickpea genotypes having resistance to drought/heat stress and to identify the most appropriate selection criteria for this. A total of 377 chickpea accessions were sown 2 months later than normal for the Antalya region (Turkey) to increase their exposure to the drought and high‐temperature conditions of a typical summer in this part of the world. Interspersed between every 10 test genotypes as benchmark genotypes, were plants of the two known genotypes ILC 3279 (drought‐susceptible) and ILC 8617 (drought‐susceptible), while ICC 4958 (known drought‐resistant) and ICCV 96029 (known very early, double‐podded) were also sown for confirmation. All plants were subsequently screened for drought and heat stress resistance. Soon after the two known susceptible genotypes had died, evaluations of the entire trial were made visually on a scale from ‘1’ (free from drought/heat damage) to ‘9’ (all plants died from drought/heat). Yield loss in many of the test genotypes and in the two known susceptible genotypes (ILC 3279 and ILC 8617) rose to 100 %. The desi chickpeas (smaller, dark seeds) were generally more drought‐ and heat‐resistant than the kabuli chickpeas (larger, pale seeds). Two desi chickpeas, ACC 316 and ACC 317, were selected for drought and heat (>40 °C) resistance under field conditions. Seed weight was the trait least affected by adverse environmental conditions and having the highest heritability, and it should be used in early breeding selections. When breeding drought‐ and heat‐resistant chickpeas, path and multivariate analyses showed that days to the first flowering and maturity to escape terminal drought and heat stresses should be evaluated ahead of many other phenological traits, and harvest index, biological yield and pods per plant for increased yield should also be considered.     

Relationship Between Cold Severity and Yield Loss in Chickpea (Cicer arietinum L.)*

Seed yield in chickpea (Cicer arietinum L.) is substantially increased by advancing sowing date from the traditional spring to early winter at low to medium elevation areas around the Mediterranean Sea. This shift, however, increases the probability of the exposure to subzero temperatures as low as -10 °C for up to 60 days in a year. These low temperatures often reduce seed yield of cold-susceptible cultivars. Yield losses from cold were estimated in two experiments conducted at Tel Hadya, Syria. In experiment 1, of 96 genotypes sown on nine dates ranging from autumn to spring during the 1981–82 season, those lacking tolerance to cold were killed and produced no yield in autumn sowing, whereas lines with cold tolerance produced nearly 4 t/ha which corresponds to a four-fold increase over spring sowing. Moderately cold-tolerant genotypes sown during early winter produced substantially more seed yield than the normal spring-sown crop. Seedlings were more cold tolerant than the plants in early or late vegetative stages. In experiment 2, in which yield loss due to cold in the field was estimated in 12 yield trials comprising 288 newly bred lines in the 1989–90 season, the regression of cold susceptibility on seed yield in each of the trials was highly significant and negative. On average, winter-sown trials produced 67 % more seed yield than spring-sown trials, but 125 out of 288 genotypes produced yield more than double in winter sowing. Early maturing lines suffered severe cold damage and many lines produced no seed.     

Breeding for improved drought tolerance in Chickpea (Cicer arietinum L.)

Chickpea (Cicer arietinum L.) is an important legume crop as a protein source across the world. It is mostly grown on arid and marginal lands where it faces drought stress at different growth stages. Drought stress exerts drastic effects on nutrient uptake, hinders the nodule formation and adversely affects yield and yield components. Generally drought at any growth stage and organizational level is responsible for reduction in economic yield. Significant variability in chickpea germplasm is present on the basis of responses to drought stress in the form of drought escape, drought avoidance and drought tolerance; these mechanisms prevent chickpea crop from harmful effects of drought. Improvement in chickpea germplasm against drought stress could be made by using several breeding approaches, that is introduction, hybridization, mutation breeding, marker‐assisted breeding and omic techniques. These breeding approaches, especially marker‐assisted breeding and omics, are further strengthened with the availability of the chickpea genome sequence. This review highlighted the significance, status and advances in different breeding strategies for improvement of drought tolerance in chickpea.     

Alterations in Photochemical and Physiological Activities of Chickpea (Cicer arietinum L.) Cultivars under Drought Stress

In this study, some morphological, physiological and biochemical parameters of two chickpea cultivars, cv. Gökçe and Canıtez, were analysed to understand their tolerance to drought stress. Twenty-day-old plants were subjected to three different regimes of drought stress by withholding water for 3, 5 or 7 days, and then rewatering for 2 days after the initial 7 days of drought stress. Drought treatments only reduced shoot elongation in the Canıtez cultivar. Leaf production and fresh biomass decreased in both cultivars under all drought treatments, however to a greater extent in Canıtez. In both cultivars, malondialdehyde, proline and anthocyanin accumulation increased significantly, whereas relative water content declined under drought stress. The total chlorophyll and carotenoid contents of Gökçe were not affected by drought stress, whereas the chlorophyll content of Canıtez increased greatly at the end of the treatments. Using chlorophyll a fluorescence measurements, we found that extended drought treatment caused photoinhibition of PSII activity in both cultivars. However, this was greater in Canıtez, especially under severe drought stress. Although Canıtez recovered quickly from drought stress and exhibited a good ability to overcome drought stress, via activation of many protection mechanisms such as increasing antioxidant enzymes and proline and anthocyanin accumulation during vegetative stage, our results show that Canıtez is less drought tolerant than Gökçe.     

Modelling Biomass Accumulation and Partitioning in Chickpea (Cicer arietinum L.)

Quantitative information regarding biomass accumulation and partitioning in chickpea (Cicer arietinum L.) is limited or inconclusive. The objective of this study was to obtain baseline values for extinction coefficient (K_S), radiation use efficiency (RUE, g MJ^?1) and biomass partitioning coefficients of chickpea crops grown under well‐watered conditions. The stability of these parameters during the crop life cycle and under different environmental and growth conditions, caused by season and sowing date and density, were also evaluated. Two field experiments, each with three sowing dates and four plant densities, were conducted during 2002–2004. Crop leaf area index, light interception and crop biomass were measured between emergence and maturity. A K_S value of 0.5 was obtained. An average RUE of 1 g MJ^?1 was obtained. Plant density had no effect on RUE, but some effects of temperature were detected. There was no effect of solar radiation or vapour pressure deficit on RUE when RUE values were corrected for the effect of temperature. RUE was constant during the whole crop cycle. A biphasic pattern was found for biomass partitioning between leaves and stems before first‐seed stage. At lower levels of total dry matter, 54 % of biomass produced was allocated to leaves, but at higher levels of total dry matter, i.e. under favourable and prolonged conditions for vegetative growth, this portion decreased to 28 %. During the period from first‐pod to first‐seed, 60 % of biomass produced went to stems, 27 % to pods and 13 % to leaves. During the period from first‐seed to maturity, 83 % of biomass was partitioned to pods. It was concluded that using fixed partitioning coefficients after first‐seed are not as effective as they are before this stage. Environmental conditions (temperature and solar radiation) and plant density did not affect partitioning of biomass.     

Salinity Effects on the Growth and Ion Contents of Some Chickpea (Cicer arietinum L.) and Lentil (Lens culinaris Medic.) Varieties

The effect of salinity on seed germination, plant yield parameters, and plant Na, Cl and K concentrations of chickpea and lentil varieties was studied. Results showed that in both crops percentage emergence was significantly reduced by increasing NaCl levels (0–8dSm^?1). From the plant growth studies it was found that differences existed among chickpea and lentil varieties in their response to NaCl application. In chickpea, the variety Mariye showed the comparatively lowest germination percentage and the lowest seedling shoot dry weight in response to salinity and was also among the two varieties which had the lowest relative plant height, shoot and root dry weight and grain yield at maturity. Similarly, variety DZ-10-16-2, which was the second best in germination percentage and the highest in terms of seedling shoot dry weight, also had the highest relative plant height, shoot and root dry weights, and grain yield at maturity. In lentil, however, such relationships were less pronounced. Chloride concentration (mg g^?1) in the plant parts at salt levels other than the control was about 2–5 times that of Na. K concentration in the plants was significantly reduced by increasing NaCl levels. Chickpea was generally more sensitive to NaCl salinity than lentil. While no seeds were produced at salinity levels beyond 2dSm^?1 in chickpea (no seeds were produced at this salt level in the most sensitive variety, Mariye), most lentil varieties could produce some seeds up to the highest level of NaCl application. Overall, varieties R-186 (lentil) and Mariye (chickpea) were the most sensitive of all varieties. On the other hand, lentil variety NEL-2704 and chickpea variety DZ-10-16-2 gave comparatively higher mean relative shoot and root dry weights, and grain yield, thus showing some degree of superiority over the others. The observed variations among the varieties may be useful indications for screening varieties of both crops for salt tolerance.     

The Effects of Temperature and Soil Moisture on Chickpea (Cicer arietinum L.) Genotype Sensitivity to Isoxaflutole

Isoxaflutole at 75 g ai ha^?1 is registered in Australia for the control of several broadleaf weeds in chickpea (Cicer arietinum L.). Although isoxaflutole provides satisfactory control of problematic weeds, under certain conditions crop injury can occur. Higher air temperature and moisture content of soil are reported to affect the metabolism of soil applied herbicide. Controlled environment experiments were used to determine the tolerance of chickpea to isoxaflutole under a range of temperature and soil moisture levels. For the soil moisture study, the variables examined were two desi chickpea genotypes (Kyabra as a tolerant cultivar and Yorker as a sensitive cultivar), three soil moisture levels [50 % field capacity (FC), 75 % FC and FC] with three herbicide rates [0, 75 (recommended rate) and 300 g ai ha^?1]. For the temperature by soil moisture study, the variables examined were two other desi chickpea genotypes (97039‐1275 as a tolerant line and 91025‐3021 as a sensitive line), three temperature regimes (20/5, 30/15 and 35/25 °C), two soil moisture conditions (50 % FC and FC) with the same three herbicide rates. The results demonstrated that the chickpea genotypes exhibited differential tolerance to isoxaflutole, but that differences in response were affected by rate, temperature and soil moisture. Increasing temperature and soil moisture content made the susceptible chickpea genotype more vulnerable to isoxaflutole damage. Injury to the susceptible genotype in terms of increased leaf chlorosis and reduction in shoot height and dry matter production increased as soil moisture increased from 50 % FC to FC and temperature increased from 20/5 to 35/25 °C. Overall damage of the sensitive genotype from increasing rates of isoxaflutole also increased when soil moisture content increased from 50 % FC to FC within the fixed temperature regime of 30/15 °C. The sensitivity of chickpea to isoxaflutole depends on existing temperature and moisture content and the chances of crop damage were enhanced with increasing temperature and moisture levels.     

Low Temperature Effects during Seed Filling on Chickpea Genotypes (Cicer arietinum L.): Probing Mechanisms affecting Seed Reserves and Yield

Chickpea is sensitive to cold conditions (<15 °C), particularly at its reproductive phase and consequently it experiences significant decrease in the seed yield. The information about the effects of cold stress on chickpea during the seed filling phase is lacking. Moreover, the underlying metabolic reasons associated with the low temperature injury are largely unknown in the crop. Hence, the present study was undertaken with the objectives: (i) to find out the possible mechanisms leading to low temperature damage during the seed filling and (ii) to investigate the relative response of the microcarpa (Desi) and the macrocarpa (Kabuli) chickpea types along with elucidation of the possible mechanisms governing the differential cold sensitivity at this stage. At the time of initiation of the seed filling (pod size ∼1 cm), a set of plants growing under warm conditions of the glasshouse (temperature: 17/28 ± 2 °C as average night and day temperature) was subjected to cold conditions of the field (2.3/11.7 ± 2 °C as average night and day temperature), while another set was maintained under warm conditions (control). The chilling conditions resulted in the increase in electrolyte leakage, the loss of chlorophyll, the decrease in sucrose content and the reduction in water status in leaves, which occurred to a greater extent in the macrocarpa type than in the microcarpa type. The total plant weight decreased to the same level in both the chickpea types, whereas the rate and duration of the seed filling, seed size, seed weight, pods per plant and harvest index decreased greatly in the macrocarpa type. The stressed seeds of both the chickpea types experienced marked reduction in the accumulation of starch, proteins, fats, crude fibre, protein fractions (albumins, globulins, prolamins and glutelins) with a larger decrease in the macrocarpa type. The accumulation of sucrose and the activity levels of the enzymes like starch synthase, sucrose synthase and invertase decreased significantly in the seeds because of the chilling, indicating impairment in sucrose import. Minerals such as calcium, phosphorous and iron as well as several amino acids (phenylalanine, tyrosine, threonine, tryptophan, valine and histidine) were lowered significantly in the stressed seeds. These components were limited to a higher extent in the macrocarpa type indicating higher cold sensitivity of this type.     

Two major genes for seed size in chickpea (Cicer arietinum L.)

Summary Seed size as determined by seed weight, is an important trait for trade and component of yield and adaptation in chickpea (Cicer arietinum L.). Inheritance of seed size in chickpea was studied in a cross between ICC11255, a normal seed size parent (average 120 mg seed⁻¹) and ICC 5002, a small seed size parent (average 50 mg seed⁻¹). Seed weight observations on individual plants of parents, F₁, F₂, and backcross generations, along with reciprocal cross generations revealed that the normal seed size was dominant over small seed size. No maternal effect was detected for seed size. The numbers of individuals with normal, small and medium (average 150 mg seed⁻¹) seed sizes in F ₂ population were 1237, 323 and 111 fitting well to the expected ratio of 12:3:1 (χ² = 0.923, P = 0.630). The segregation data of backcross generations also indicated that seed size in chickpea was controlled by two genes with dominance epistasis. We designate the genotype of ICC 11255 as Sd ₁ Sd ₁ sd ₂ sd ₂, and ICC 5002 as sd ₁ sd ₁Sd₂ Sd ₂ wherein Sd ₁ is epistatic to Sd ₂ and sd ₂ alleles.     

Genotypic Variation in Root Systems of Chickpea (Cicer arietinum L.) across Environments

Root systems of various chickpea genotypes were studied over time and in diverse environments, – varying in soil bulk density, phosphorus (P) levels and moisture regimes. In a pot study comparing a range of chickpea genotypes, ICC 4958 and ICCV 94916‐4 produced higher root length density (RLD) and root dry weight (RDW), which were better expressed under P stress conditions. In two field experiments in soils of intermediate and high soil bulk densities, ICC 4958 also had greater RLD and RDW, particularly under soil moisture stress conditions. The expression of greater rooting ability of ICC 4958 under a wide range of environmental conditions confirms its suitability as a parent for genetically enhancing drought resistance and P acquisition ability. The superiority of ICC 4958 over other genotypes was for root proliferation expressed through RLD. Thus, the variation in RLD can be the most relevant root trait that reflects chickpea's potential for soil moisture or P acquisition.     

Induction and inheritance of determinate growth habit in chickpea (Cicer arietinum L.)

Summary The character of determinate plant growth has not been reported for chickpea and has not been observed in the world germplasm collection at ICRISAT, Patancheru, India. A determinate growth habit would be desirable where growing conditions often lead to excessive vegetative growth. We attempted to generate this trait by mutation breeding. Seeds of the cultivar ICCV 6 were exposed to varying irradiation treatments, M₁ and M₂ populations were raised, and in the latter one plant was detected that showed the determinate growth habit and female sterility. The character of determinate growth segregated in a postulated digenic epistatic 3:13 fashion in the F₂ and confirmed its digenic mode of inheritance in the F₃ and F₄. The symbol cd is proposed for the allele conditioning for determinancy and Dt for the allele expressing the determinate trait. Continued mutation breeding with this and other material may result in identifying fully fertile, determinate plant types.Abbreviations DT - determinate - IDT - indeterminate ICRISAT Journal Article No. 1396.     

Leaf types and their genetics in chickpea (Cicer arietinum L.)

Summary Commonly the chickpea leaf is uni-imparipinnate, having 9–15 leaflets. However, certain variants have been reported; these are available in the chickpea collection at ICRISAT and were re-examined. Based on the lamina differentiation, three major classes of leaf type can be recognized: uni-imparipinnate (normal), multipinnate and simple (leaf). (Certain other leaf forms reported earlier are not classes of leaf type though they are distinct variants). It was determined that the leaf type differences are governed by two genes (mlsl), which show supplementary gene action. The multipinnate leaf is formed when the first gene is dominant (ml⁺sl/.sl). Whereas the simple leaf occurs when the first gene is recessive and the second gene is in either form (ml./ml.), the normal leaf is expressed when both dominant genes are present (ml⁺sl⁺/..).Submitted as J.A. No. 814 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).     

Genetics for speed of plumule emergence in chickpea (Cicer arietinum L.)

Summary Genetics for speed of plumule emergence was studied using six generations (P₁, P₂, F₁, BC₁(P₁), BC₂(P₂) and F₂) in three crosses. Two of the crosses which had parents of different emergence speed were controlled by two genes with duplicate epistasis. The third cross which involved parents of little difference for speed, indicated incomplete dominance for one gene of bit fast parent over the slow one. In all the crosses F₂ segregation pattern was confirmed by the segregation pattern of back crosses. The gene symbols were designated as Sp1Sp1 Sp2Sp2 for fast speed parents: sp1sp1 sp2sp2 for slow parent and sp1sp1 Sp2Sp2 for the parent with bit fastness for speed of plumule emergence.     

Interactive Effects of Salinity and Biological Nitrogen Fixation on Chickpea (Cicer arietinum L.) Growth

The effect of salinity on the nodulation, N-fixation and plant growth of selected chickpea- Rhizobium symbionts was studied- Eighteen chickpea rhizobial strains were evaluated for their growth in a broth culture at salinity levels of 0 to 20 dS m⁻¹ of NaCl + Na₂SO₄. Variability in response was high. Salinity generally reduced the lag phase and/or slowed the log phase of multiplication of Rhizobium. Nine chickpea genotypes were also evaluated for salt tolerance during germination and early seedling growth in Petri dishes at five salinity levels (0–32 dS m⁻¹). Chickpea genotypes ILC-205 and ILC-1919 were the most salt-tolerant genotypes. The selected rhizobial strains and chickpea cultivars were combined in a pot experiment aimed at investigating the interactive effect of salinity (3, 6 and 9 dS m⁻¹) and N source (symbiosis vs. inorganic N) on plant growth. Symbiotic plants were more sensitive to salinity than plants fed mineral N. Significant reductions in nodule dry weight (59.8 %) and N fixation (63.5 %) were evident even at the lowest salinity level of 3 dS m-¹. Although nodules were observed in inoculated plants grown at 6 dS m-¹, N-fixation was completely inhibited. The findings indicate that symbiosis is more salt-sensitive than both Rhizobium and the host plant, probably due to a breakdown in one of the processes involved in symbiotic-N fixation. Improvement of salinity tolerance in field grown chickpea may be achieved by application of sufficient amounts of mineral nitrogen.     

Selection of High Nitrogen-Fixing Rhizobia Nodulating Chickpea (Cicer arietinum) for Semi-Arid Tunisia

Inoculation of grain legumes with rhizobia may improve biological N₂ fixation and crop yield. However, drought, high temperature and soil salinity constrain legume root-nodule formation and function. Here, two rhizobial strains nodulating Tunisian chickpea, Mesorhizobium ciceri strain CMG 6 and Mesorhizobium mediterraneum strain CTM 226 originating from semi-arid regions, were selected for their symbiotic performance and their salt stress tolerance (3 % NaCl). Both strains were then examined as inoculants in different soils and field conditions. Field experiments were conducted in four sites using four chickpea cultivars. Rhizobia occupying nodules in non-inoculated plots were isolated and characterized using 16S rDNA typing; to examine nodule occupancy by the inoculant strains we used polymerase chain reaction (PCR)-restriction fragment length polymorphism of 16S rDNA gene and repetitive extragenic palindromic PCR. The inoculant strains gave a significant increase in nodule number, shoot dry weight and grain yield in all the experimented fields for the four cultivars used, even in the non-irrigated soils. The improvement in plant production was equal to or better than nitrogen fertilization. Moreover, the monitoring of the nodule occupancy showed that inoculant strains competed well in the native populations of rhizobia. These results suggest that nodulation and yield of chickpea can be improved by inoculation with competitive and salt-tolerant rhizobia and is economically promising to increase chickpea production in water-limited regions.     

Inheritance of Seed Coat Thickness in Chickpea (Cicer arietinum L.) and its Evolutionary Implications

The desi and kabuli chickpeas are characterized, among other things, by their seed coats being thicker in the desi than in the kabuli type. The inheritance of seed coat thickness, and its relation to flower colour and seed size, was studied. Seed coat thickness exhibits monogenic inheritance, the thin kabuli seed coat being the recessive character. Linkage was found between seed coat thickness and flower colour, the recombinant fraction being 0.19. No relationship was found between seed coat thickness and seed size. The role of these characters in the evolution of the chickpea is discussed.     

Two new traits - open flower and small leaf in chickpea (Cicer arietinum L.)

Two new traits – open flower and small leaf in chickpea are discussed. Open flower, a natural mutant in a good agronomic background is reported for the first time, small leaf trait has been reported earlier, and has now been studied by breeders. Both useful traits were found to be monogenic recessive. The joint F₂ segregation data revealed no linkage between flower colour and flower type, but flower type and leaf size showed some linkage. Open flower could contribute to a higher rate of cross pollination and utilization of heterosis. The small leaf allows light to penetrate the crop canopy, and could be useful in designing a physiologically efficient plant type in chickpea. This revised version was published online in July 2006 with corrections to the Cover Date.