Genetic Analysis of Developmental Traits in Chickpea

Chickpea (Cicer arietinum L.) is an important legume crop in India. The present study was conducted to investigate the inheritance of several developmental traits in three crosses of chickpea, viz., WFWG III’בT20’, ‘T88’בBold Seeded’, and ‘NP34’בP1528-1-1’, each having seven generations. The seven generations were P₁, P₂, F₁, B₁, B₂, F₂, and F₃. The experimental lay-out was randomized complete block design with three replications. Data were acquired on days to flowering (DF), days to maturity (DM), plant height in cm (PH), number of primary branches (PB), and number of secondary branches (SB). Generation mean analysis was used to estimate the genetic components; narrow sense heritability was estimated using variance components; and correlation analysis to estimate correlation coefficients among different traits. Genetic differences were found in all three crosses for all traits studied. Additive, dominance, and epistatic effects were found for many traits'. Duplicate epistasis was observed for all traits except number of PB. Higher order interactions and/or linkage were detected for DM and SB. For many traits the relative magnitudes of the genetic effects differed among crosses, thus the extrapolation to other crosses may be difficult. The inheritance becomes more complex as the fate of the character is decided at a later stage in the life cycle. Positive heterosis was observed for some traits, but the exploitation of this component may not Feasible since stable male sterile lines are not available. Early maturity and high yield ‘may be selected independently because of the absence of any significant correlation between these two traits.     

Genetic Variations and Adaptations in Chickpea

A total of 329 chickpea lines, comprising 130 kabiili and 199 desi types, originating from six regions, viz., Indian sub-continent, Middle East, North Africa, America, Europe and USSR, were sown in augmented design. The data recorded on agronomic characters on all entries from each region were evaluated in terms of group (region) means. Among the six regions, greater plant height and lateness in flowering were specific to USSR entries. Group means of USSR accessions, both desi and kabuli, differed significantly from those of Indian varieties for a majority of the characters. These observations indicate that the degree of expression of certain characters could be ascribed to specific areas, which led to area-specific adaptations. Furthermore, type-specific differentiating characters, differing in degree of expression, were observed in desi and kabuli types. For example, high mean values of characters, like branches, pods, grain yield and harvest index, were associated with desi types, and 100-seed weight with kabulis. History of cultivation and selection for specific purpose has been cited as cause for area-specific adaptations and type-specific differentiating characters.     

Inheritance of Dry Root Rot (Rhizoctonia bataticola) Resistance in Chickpea (Cicer arietinum)

The inheritance of resistance to dry root rot of chickpea caused by Rhizoctonia bataticola was studied. Parental F₁ and F₂ populations of two resistant and two susceptible parents, along with 49 F₁ progenies of one of the resistant × susceptible crosses were rested for their reaction to dry root rot using the blotting-paper technique. All F, plants of the resistant × susceptible crosses were resistant; the F₂ generation fitted a 3 resistant: 1 susceptible ratio indicating monogenic inheritance, with resistance dominant over susceptibility. F³ family segregation data confirmed the results. No segregation occurred among the progeny of resistant × resistant and susceptible × susceptible crosses.     

Evaluation of Early Generation Testing in Chickpea1)

Inter-generation correlations between F₂-F₃, F₂-F₄ and F₃-F₄ in six crosses of chickpea were calculated by using individual plant/progeny means. In general, correlation values in case of plant height, seeds per pod and 100-seed weight were higher between F₃ and F₄ than those between F₂ and F₃ and F₂ and F₄. However, inter-generation correlations were mostly non-significant in case of pods per plant and grain yield. These results clearly show that selection in F₃ can be fruitful for seeds per pod and 100-seed weight. However, selection for pods per plant and grain yield in early generations may not show any relationship with later generation performance for these traits.     

Transferability of Chickpea Selection Indices from Normal to Drought-prone Growing Conditions in a Mediterranean Environment*

Chickpea (Cicer arietinum L.) is normally grown as a spring-sown rainfed crop in the Mediterranean region in areas receiving more than 400 mm of rainfall annually. Because of large fluctuations in the total amount and distribution of the rainfall, the crop occasionally suffers from extreme terminal drought. Breeders face a dilemma in selecting materials for both normal moisture regimes and drought conditions because it is often difficult to conduct two parallel breeding programmes. This study examines the transferability of the selection indices (developed as a multiple regression of yield on most influential traits) from one environment to another with the objective of selecting an appropriate environment for the development of cultivars adapted to both environments. Experiments were conducted for 3 years (1989-1991) during the spring at two locations with normal moisture regime (hereafter referred to as drought-free) in Syria and Lebanon and one drought-prone location in Syria. Each year, 192-240 newly bred lines were evaluated in replicated trials for seed yield, days to flowering and maturity, plant height and 100-seed weight. Correlation analyses showed that increased seed size, early maturity and reduced plant height at the drought-prone location and early maturity at the drought-free location were of prime importance in increasing seed yield. Regression equations developed to predict seed yield showed that days to flower and maturity accounted from 67-80 % variation in seed yield at the dry location, whereas at the drought-free locations the contribution of days to maturity was smaller except in 1991 in Lebanon. The percent success in the transferability of the selection indices from the drought-free environments to the drought-prone environment was higher than that from the drought-prone environment to the drought-free environment. These results indicate that chickpea breeding material developed under drought-free environments could be useful under drought-prone conditions. Early-maturing lines selected under normal environments would also perform well under drier conditions.     

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.     

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.     

Effect of Sodium Chloride Salinity on Seedling Emergence in Chickpea

Although laboratory (Petri dish) germination as an estimate of seed viability is a standard practice, it may not give an accurate prediction of seedling emergence in the field, especially when saline irrigation water is used. Experiments were conducted to investigate seedling emergence in two chickpea cultivars (ILC 482 and Barka local) in response to varied salinity levels and sowing depths. Seeds were sown in potted soil at a depth of 2, 4 or 6 cm. The salinity treatments were 4.6, 8.4 and 12.2 dS m^–1. Tap water (0.8 dS m^–1) served as the control. Depth of sowing had a significant effect on seedling emergence. Seeds sown 6 cm deep showed the lowest seedling emergence. Similarly, salinity had an adverse effect on seedling emergence. The lowest seedling emergence percentages were obtained at the highest salinity treatment (12.2 dS m^–1). The interaction between salinity treatment and seeding depth was significant. Hypocotyl injury was implicated as a possible cause of poor seedling emergence in chickpea under saline water irrigation and was less severe when pre-germinated seeds were used. ILC 482 appeared to be more tolerant to salinity than Barka local, suggesting that breeding programmes involving regional exchange of germplasm may be helpful.     

Genetic diversity estimates in Cicer using AFLP analysis

Amplified fragment length polymorphism (AFLP) analysis was used to evaluate the genetic variation among cultivated chickpea and wild Cicer relatives. In total, 214 marker loci were assessed, of which 211 were polymorphic (98.6%) across the 95 accessions that represented 17 species of Cicer. The genetic variation within a species was highest in C. pinnatifidum followed by C. reticulatum and lowest in C. macracanthum. Three main species groups were identified by UPGMA clustering using Nei's pair‐wise distance calculations. Group I included the cultivated species C. arietinum, C. reticulatum and C. echinospermum. Within this group, C. reticulatum accessions were clustered closest to the C. arietinum cultivars ‘Lasseter’, ‘Kaniva’ and ‘Bumper’, supporting the hypothesis that C. reticulatum is the most probable progenitor of the cultivated species. Cicer bijugum, C. judaicum and C. pinnatifidum were clustered together creating group II. Group III contained all nine perennial species assessed and two annual species C. yamashitae and C. cuneatum. The genetic distance detected between group I and group III (0.13) was equivalent to the genetic distance detected between group I and group II (the primary and annual tertiary species, respectively; 0.14). This indicated that the perennial tertiary species may be as valuable for increasing variation to incorporate novel germplasm in the cultigen as the annual tertiary species.     

Seed Priming Increases Crop Yield Possibly by Modulating Enzymes of Sucrose Metabolism in Chickpea

The number of seeds and seed yield per plant were higher in chickpea crops raised from water and mannitol (4 %) primed seeds in comparison with the control non-primed crops. In primed plants, an enhanced acid invertase activity in the apical part of the main stem and the part immediately below it at 100 and 130 days after sowing (DAS) might result in an increased availability of hexoses to these plant parts. In addition, decreased acid invertase activity at the point of initiation of branches and in the internodes of stem observed in primed plants indicated restricted hydrolysis of sucrose during its transport through the stem, resulting in its more supply to the actively growing sinks. The activities of sucrose-cleaving enzymes, i.e. invertase and sucrose synthase (SS) in podwall of primed plants were higher at 110 DAS. At 140 DAS, a stage of rapid seed filling, increased activities of SS and sucrose phosphate synthase (SPS) were observed in seeds of primed plants. Increased SPS activity in seeds of primed crop could meet the increased assimilate requirements of the developing seeds. Higher activity of SS in seeds of primed crop may facilitate seed filling. These data suggest that enzymes of sucrose metabolism play an important role in increasing the yield of chickpea crops raised from primed seeds.     

Genetic control of seed weight and calcium concentration in chickpea seed

Chickpea, Cicer arietinum L., is a staple protein source in many Asian and Middle Eastern countries. Hence, the mineral content of its seed, especially that of calcium, is of nutritional importance. Calcium is transported through plants and to legume pods almost exclusively via the xylem stream, with Ca accretion in developing seeds resulting primarily from diffusion of Ca from the adjoining pod wall. Thus, for seeds of differing surface‐to‐mass ratios, Ca concentration is expected to correlate inversely with seed weight. The relationship between seed weight and Ca concentration in chickpea seeds was studied using a range of germplasm and derivatives from crosses between types differing in seed Ca concentration. Among the cultivars tested, low seed mass was associated with high Ca concentration. However, the study of hybrid progeny indicated that seed Ca content was mainly determined by genetic factors other than grain weight genes. This finding may assist in future breeding of high nutritional quality chickpea cultivars.     

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.     

Shading,Defoliation and Light Enrichment Effects on Chickpea in Northern Latitudes

Chickpea (Cicer arietinum L.) has an indeterminate growth nature, and the plant canopy with an improved light environment during critical growth stages may increase biomass (BM) production and improve crop yield. This study examined (i) the effects of shading, light enrichment and defoliation applied at various growth stages on BM and seed yield of chickpea in northern latitudes; and (ii) the difference between cultivars with fern‐ vs. unfoliate‐leaf type in responding to the altered canopy light environments. Field studies were conducted at Saskatoon and Swift Current, Saskatchewan in 2004 and 2005. Different light environments were created by 50 % defoliation at vegetative growth and at first flower, 50 % shading from vegetative growth to first flower, and two light enrichment treatments initiated at the first flower and pod formation stages. The 50 % shade treatment prior to flowering significantly decreased harvest index (HI) and seed yield. Light enrichments increased seed yield only one of three location‐years (the fourth site excluded because of disease damage). Defoliation at vegetative growth or first flower had a marginal effect on seed yield, largely as a result of the regrowth of vegetative tissues compensating for the lost plant tissues. The cultivar CDC Yuma (fern‐leaf type) exhibited consistently greater maximum light interception (LI), cumulative intercepted radiation, HI and seed yield than the cultivar Sanford (unifoliate‐leaf type) across all location‐years. Selective use of chickpea cultivars with improved morphological traits such as fern‐leaf type will likely improve LI and increase crop yield for chickpea in northern latitudes. Moreover, optimized crop management practices should be adopted to ensure that chickpea be grown under conditions with minimum shading before flowering and optimum light environment within the canopy especially during reproductive growth period.     

Allelic Variation within Single Podded Gene Characterized by STMS Marker in Chickpea

Chickpea （Cicer arietinum L.）, is an important grain legume crop throughout the world especially in developing countries. However the average yield worldwide is considered to be lower than its potential yield （Singh et al., 1994）. The average yield of chickpea is much lower in Pakistan, which is about 5500-650 kg/hm^2 due to various abiotic and biotic stresses （Shah et al., 2005）.     

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.     

Broad-few-leaflets and outwardly curved wings: two new mutants of chickpea

This study was aimed at the induction of morphological mutations for increasing genetic variability and making available additional genetic markers for linkage studies in chickpea (Cicer arietinum L.). A wilt‐resistant, well‐adapted chickpea cultivar of central India,‘JG 315’(Jawahar gram 315), was used for the induction of mutations. Seeds presoaked in distilled water for 2 h were treated with ethyl methane sulphonate (EMS) using six different concentrations (0.1, 0.2, 0.3, 0.4, 0.5 and 0.6%) and two different durations (6 and 8 h). Several morphological mutants were identified in M₂. One of the mutants, isolated from a treatment of 0.3% EMS for 8 h, had five to nine large leaflets per leaf in comparison with 11‐17 normal‐sized leaflets per leaf observed in the parental cultivar ‘JG 315′. The mutant was designated broad‐few‐leaflets. Many leaves of this mutant showed a cluster of three to five overlapping leaflets at the terminal end. The other mutant, designated outwardly curved wings, was isolated from the 0.5% EMS treatment for 6 h. In this mutant, the wings were curved outwards, exposing the keel petal, while the wings in typical chickpea flowers are incurved and enclose the keel. The lines developed from the broad‐few‐leaflets and outwardly curved wings mutants were named JGM 4 (Jawahar gram mutant 4) and JGM 5, respectively. Inheritance studies indicated that each of these mutant traits is governed by a single recessive gene. The gene for broad‐few‐leaflets was designated bfl and the gene for outwardly curved wings was designated ocw. The locus bfl was found to be linked with the locus lg (light green foliage) with a map distance of 18.7 ± 6.3 cM.     

粳稻稻米外观和碾磨品质性状与植株农艺性状的遗传关系分析

研究了不同环境条件下粳稻稻米外观品质、碾磨品质与植株农艺性状间的遗传关系.结果表明,糙米长、糙米宽、垩白率、透明度等外观品质性状以及糙米率、精米率、整精米率等碾磨品质性状与大多数植株农艺性状间存在极显著的正向或负向协方差.稻米外观品质性状与单株穗数、千粒重等性状间主要表现为遗传主效应协方差,垩白率、透明     

On improving crossing success in chickpea

Artificial hybridization in chickpea (Cicer arietinum L.) is a tedious operation with known low rate of success. A study conducted at the University of Saskatchewan showed that crossing success was influenced by parental identity in this crop. Percent pod set to the total flowers pollinated in chickpea crosses was significantly increased when the smaller‐seeded parent was used as the female. Also, success rate increased with the size of the leaf subtending female parent's flowers at the time of crossing.