The Genotypic and Phenotypic Basis of Chickpea (Cicer arietinum L.) Cultivars for Irrigation-Based Production in Ethiopia

Development of irrigation-based chickpea production is considered the most important alternative approach in combating climate change and maximizing productivity, especially in moisture-stress areas and in areas where water and land for irrigation is available. In central Ethiopia, where production of chickpea (especially Kabuli type) is becoming an important part of agriculture, although many superior varieties (both desi and Kabuli types) are available, they have been evaluated and released based on rainfed production. Hence, there is an urgent need for evaluation of varieties suited for irrigation-based production. Towards this goal, during the 2012/13 growing season, 14 Kabuli genotypes (previously introduced) and 24 desi genotypes (nurseries obtained from ICRISAT) were evaluated independently at three and one locations respectively (Kabuli at Debre Zeit, Ambo and Werer; desi at Debre Zeit) for production adaptation under irrigation. The parameters evaluated were date of maturity, 100-seed weight and yield. Overall, while most Kabuli genotypes showed high adaptability to irrigation-based production at all locations, four Kabuli genotypes (X96TH-52-14/2000 = 106.7DAS, FLIP-02-39C = 107DAS, X98TH-51-1-3 = 107.9DAS and ICCV-07313 = 107DAS) were found to be earlier in maturity; two genotypes (ICCV-07313 = 42.5 g and ICCV-04305 = 37.8 g) were identified as having high 100-seed weight and one genotype (ICCV-05309 = 3228.8 kg/ha or 32 quintals/ha) out yielded all genotypes across locations. The result of combined analysis indicated five promising genotypes showing more than 20 kg/ha yield on average. All desi varieties showed maturity dates of under four months; six genotypes showed higher 100-seed weight and eight genotypes showed promising yield responses (> 2000 kg/ha). From these preliminary results, it can be deduced that irrigation can play a significantly complementary role to the rainfed system, provided the genetics by management is optimized through research and innovation.


Introduction
Chickpea (Cicer arietinum) is one of the most important cool-season annual grain legumes grown in more than 50 countries (89.7% area in Asia, 4.3% in Africa, 2.6% in Oceania, 2.9% in the Americas and 0.4% in Europe) with India taking the largest share (64%) of the global production. Countries such as Pakistan, Turkey, Iran, Australia, Ethiopia, Canada, Mexico and Iraq are also important chickpea-producing countries . In Ethiopia, chickpea holds third place as a grain legume both by area coverage and volume of production, next to faba bean and haricot bean (CSA, 2016). There are two distinct types of chickpea identified (Muehlbauer et al., 1982;Jukanti et al., 2012): Chickpea is cultivated for different values it provides, whether in nutrition, food and environmental rehabilitation, or in cash generation. Its nutritional value, medicinal value and market value, as compared to other annual crops, are some of the most important merits for which the crop is grown in Ethiopia. Nutritionally, the chickpea seed has 38-59% carbohydrate, 3% fiber, 4.8-5.5% oil, 3% ash, 0.2% calcium and 0.3% phosphorus. Digestibility varies from 76-78% for its protein and 57-60% for its carbohydrate (Hulse, 1991;Kumar et al., 2016). Pulses such as chickpeas are important sources of macronutrients, containing almost twice the amount of protein compared to cereal grains (Brick et al., 2003). They are good sources of fiber, folic acid, manganese, iron, magnesium, copper and zinc (Brick et al., 2003).
Medicinally, a cooked chickpea-milk (4:1) mixture has been found beneficial for infants, effectively controlling diarrhea . In addition, chickpea has been reported as an important means in controlling bronchitis, cholera and constipation; acids in chickpea seed are supposed to lower blood cholesterol levels . Regular consumption of pulses such as chickpeas prevents diabetes and reduces risk of heart disease .
The local consumption of chickpea in different forms for household use and local market has increased with time (CSA, 2015). Virtually all domestic pulse crop production is marketed through processors for export but the majority is sold on the local market and consumed locally. However, the quantity and quality of the product produced limit the ability of domestic producers to influence world markets and to consistently produce sufficient quantities to be a reliable supplier for large users.
Though most of the production of the crop in Ethiopia is restricted to rainfed fields, chickpea is assumed to be the most adaptive to drought, and responds better to small irrigation than other legume crops. If it is irrigated at the right time with the required amount of water, the yielding potential of the crop could be increased. Egypt and Sudan produce chickpea solely using irrigation and Egypt takes the first place in productivity with about 20 quintal/ha. Egypt irrigates the crop 1-2 times during the early stage of crop emergence and during flowering and maturity, while in Sudan chickpea is irrigated 5-7 times. Apart from the availability of irrigation water and land, availability of the most responsive varieties of chickpea suited to irrigation is very important. In Ethiopia, the potential suitable land and water resources for irrigation-based chickpea production surpasses many thousand hectares. Accordingly, the demand for varieties suitable for irrigation is soaring. To address this and beyond, the National Chickpea Improvement Program has put in place over location response assessment of pipeline germplasm to evaluate and characterize their inherent responses, and its stability. Therefore, this study is designed to develop cultivars suited for an irrigation-based production system in Ethiopia.

Description of Study Area
Experiments were conducted at Debre Zeit Agricultural Research Center, Werer Agricultural Research Center and Ambo Plant Protection Research Center at the Ethiopian Institute of Agricultural Research during 2013-2014. The agro-climatic conditions, altitude and soil characteristics of the study areas are presented in Table 1 below.

Treatments
A total of 14 early Kabuli chickpea lines were promoted from preliminary variety trial (PVT) and 24 desi chickpea lines introduced from ICRISAT were grown on-station at Debre Zeit, Ambo and Werer Agricultural Research Centers using irrigation. Planting was in four rows of plot of 4 m long and 1.2 m wide in Randomized Complete Block Design (RCBD) with three replications as shown in Figure 1. Planting was done on 10/01/2012 (for Kabuli) and 05/01/2012 (for desi) at Debre Zeit, 06/01/2012 at Ambo and 24/12/2012 at Werer since rainfall at all stations terminate before planting time and there is a dry spell following it. At all locations, the trials were surface irrigated four times using furrow irrigation and selection was made on the basis of date of maturity, 100-seed weight and yield; analysis was done using SAS software. . of the in 8 t was observed that seed priming in pre-watered plot gave the highest germination (98-100%) compared to post-watered which gave 75-85% (Table 3). Concurrently, it was also observed that phenological responses of Kabuli primed seed on pre-watered plot flowered earlier than other setups. This preliminary observation requires further experimentation and validation before substantive publication in a future issue of the journal. Note. SPT = Seed priming treatment, NPT = Non-priming treatment, GP = Germination percentage, DF = Days to flowering, SW = Seedling wilt DM = Days to maturity.
There was also a substantial difference between the genotypes for 100-seed weight at 0.05 levels. The 100-seed weight of the genotypes varied across locations; the maximum 100-seed weight for FLIP 02-13C was 45 g followed by FLIP 01-2C (41.5 g) and FLIP 01-3C (39 g) at Debre Zeit, although the 100-seed weight of these materials at Ambo and Werer were decreasing by an average of 10 g ( Table 4).

Conclusion and Recommendation
The irrigation trial undertaken on promising chickpea genotypes in 2012/13 demonstrated that irrigation is one of the major contributors in chickpea production system. There is untapped potential in production, productivity and quality to be exploited using the irrigation system. All the genotypes sown from Kabuli and desi varieties set quality seed at all locations. Except for termites at Werer, and wilt on one genotype at Debre Zeit, the occurrence of disease and insects was not detected. At some locations, the yield of some genotypes stood out as more important for our irrigation trial. Although the genotypes, especially the Kabuli types, were introduced for other purposes, they were also found to be adaptable to irrigation-based production. Of these, some genotypes performed better even in main season at Debre Zeit, as evaluated by all parameters used for analysis. From the results, we recommend that, even though all materials were not found equally important for all parameters evaluated, those genotypes which best demonstrated yield, seed size and maturity be included in the breeding program. So, genotypes with high 100-seed weight are used as parents for crossing with genotypes with low 100-seed weight, but giving high yields. It was also interesting to deal with optimization of irrigation frequency, developing responsive and suitable cultivars for the irrigation system and developing G × E stable commercial varieties in the research design. In conclusion, ICCX-090013-F2-P120-BP, FLIP 02-39C, X96TH-52-14/2000, X98TH-51-1-3 and ICCV-07313 for maturity; ICCX-090013-F2-P177-BP, FLIP 02-13C and ICCV-07313 for 100-seed weight; and ICCX-090013-F2-P216-BP, FLIP 02-13C and ICCV-05309 for yield were identified for further breeding work and yield trial for release for irrigation-based production areas.