Seed production technology of chickpea:
· Chickpea (Cicer arietinum L.) is the largest produced food legume in South Asia and the third largest produced food legume globally, after common bean (Phaseolus vulgaris L.) and field pea (Pisum sativum L.).
· Chickpea is grown in more than 50 countries (89.7% area in Asia, 4.3% in Africa, 2.6% in Oceania, 2.9% in Americas and 0.4% in Europe).
· India is the largest chickpea producing country accounting for 64% of the global chickpea production.
· The other major chickpea producing countries include Pakistan, Turkey, Iran, Myanmar, Australia, Ethiopia, Canada, Mexico and Iraq.
· Chickpea is an important source of protein for millions of people in the developing countries, particularly in South Asia, who are largely vegetarian either by choice or because of economic reasons.
· In addition to having high protein content (20-22%), chickpea is rich in fiber, minerals (phosphorus, calcium, magnesium, iron and zinc) and β-carotene.
· Chickpea meets 80% of its nitrogen (N) requirement from symbiotic nitrogen fixation and can fix up to 140 kg N ha-1 from air.
· It leaves substantial amount of residual nitrogen for subsequent crops and adds plenty of organic matter to maintain and improve soil health and fertility.
· Because of its deep tap root system, chickpea can withstand drought conditions by extracting water from deeper layers in the soil profile.
General plant characteristics
· Chickpea is a herbaceous annual and the plant height generally ranges from 30-70 cm.
· It has tap root system, which is usually deep and strong. The lateral roots develop nodules with the symbiotic Rhizobium bacteria, capable of fixing atmospheric nitrogen in plant-usable form.
· The nodules (slightly flattened, fan-like lobes) are visible about one month after plant emergence, and generally confined to the top 15 cm of the surface.
· The leaves are imparipinnate (a type of compound leaf where the leaflets are arranged along the rachis (the central stalk) with an odd number of leaflets, and the rachis ends in a single terminal leaflet.) with serrated leaflets and arise alternatively from the third node.
· The number of leaflets varies from 5 to 17. Some varieties have simple leaves.
· The entire surface of the plant shoot, except the corolla, is densely covered with fine hairs known as trichomes.
Climatic requirement
· Chickpea is a cool season food legume and grown as a winter crop in the tropics and as a summer or spring crop in the temperate environments.
· It likes cool, dry and bright weather.
· Temperature, day length and availability of moisture are the three major abiotic factors affecting flowering.
· In general, flowering is delayed under low temperatures and also under short-days.
· Chickpeas thrive in moderate temperatures, ideally between 21°C and 26°C (70°F and 80°F) during the day and above 18°C (65°F) at night.
· Chickpea is sensitive to high (maximum daily temperature >35°C) as well as low (mean of maximum and minimum daily temperatures.
Minimum standards for foundation and certified seed in chickpea
Each crop has different field and seed standards for production of foundation and certified seed. These variations are mainly because of the variation in extent and the mode of cross pollination. Being a self pollinated crop the field and seed standards for chickpea are given in Table below.
Minimum field and seed standards for chickpea seed production | ||
Parameter | Seed class | |
Foundation | Certified | |
Isolation distance (m) | 10 | 5 |
Number of field inspections | 2 | 2 |
Germination (including hard seed) (%) | 85 | 85 |
Pure Seed (%) | 98 | 98 |
Inert matter (%) | 2 | 2 |
Plants affected by seed-borne diseases (%) | 0.1 | 0.2 |
Off-types (%) | 0.1 | 0.2 |
Other crop seeds (number kg-1) | None | 5 |
Other distinguishable variety seeds (number kg-1) | 5 | 10 |
Seed production technology
A crop grown for seed production requires extra efforts and investments than a crop grown for grain. While taking up seed production, high priority should be given to maintenance of genetic and physical purity of the seed.
Crop season and sowing time:
· Chickpea is grown in rabi (postrainy season) following a kharif (rainy season) crop or kharif fallow.
· The sowing is done in the month of October or November.
· Late sowing (December-January) should be avoided as the late-sown crop may experience moisture stress and high temperatures at the critical stage of pod-filling, leading to reduced yield and seed quality.
Isolation distance:
· Isolation of a seed crop is done by maintaining a distance from other nearby fields of the same crop and other contaminating crops.
· Chickpea being a self-fertilized crop has a very low outcrossing percentage (0-1%).
· In India, an isolation distance of 10 m for foundation seed and 5 m for certified seed is required.
Suitable soil type:
· Chickpea can be successfully grown in a variety of soil types including coarse-textured sandy to fine-textured deep black soils.
· However, the best suited soils are deep loams or silty clay loams with a pH ranging from 6.0 to 8.0.
· Saline soil and fields with a high water table are not suitable for chickpea.
Field preparation:
· Chickpea plants are highly sensitive to poor aeration in the soil.
· Seedling emergence and plant growth are hindered if field surface is compact.
· Therefore, the field should have loose tilth and good drainage.
· The stubble and debris from the previous crop should be removed as these can harbor the pathogens that cause root diseases, such as collar rot.
Sowing:
· Sowing is usually done on conserved soil moisture.
· A pre-sowing irrigation may be needed, if the available soil moisture is not adequate for germination.
· Kabuli chickpea should never be irrigated immediately after sowing, particularly in deep black soils.
· This is because the kabuli chickpea seeds have thin seed coat and deteriorate faster as compared to desi type and are also more susceptible to seed rot and seedling damping off.
Sowing depth:
· Seed should be sown deeply enough to make contact with moist soil.
· A depth of 5-8 cm seems to be ideal for the emergence of chickpea.
Spacing:
· Line sowing is a must in the crop grown for seed production as it facilitates interculture operations, rouging and field inspection.
· Row-to-row spacing of 30 cm and plant-to-plant spacing of 10 cm are generally used, which give a plant population of about 33 plants per m2 (330,000 plants ha-1).
· Wider row spacing (45–60 cm) can be used in large seeded kabuli chickpea and irrigated crops (both desi and kabuli types), which are expected to have greater plant width.
· Broad bed and furrow system or ridge and furrow system are very useful for irrigation, drainage and interculture operations.
Seed rate:
· It differs from variety to variety, depending on seed size.
· For initial seed multiplication of a new variety, the multiplication rate (yield per plant) is more important than yield per unit area.
· The following guidelines may be used for seed rate:
Seed size Test wt (100-seed weight ) Seed rate
Small (less than 20 g), 50 – 60 kg ha-1
Medium (20 – 30 g), 60 – 90 kg ha-1
Large (30 – 40 g), 90 – 120 kg ha-1
Extra-large (more than 40 g), 120 – 150 kg ha-1
Seed treatment:
· The seeds should be treated with fungicides (2 g thiram + 1 g carbendazim kg-1 seed) before sowing for reducing seed and soil borne fungal diseases.
· Phosphorus solubilizing bacteria (PSB) have been identified, which improve availability of phosphorus to plants. Thus, seed treatment with PSB is recommended.
· If chickpea is being grown for the first time, the seeds should be inoculated with Rhizobium culture.
· The seeds should be treated first with fungicides and then with PSB and Rhizobium, following the procedure recommended by suppliers.
· The culture-treated seeds should be dried in the shade and sown as soon as possible thereafter.
· If the seed is to be treated with pesticides, always apply insecticides first, followed by fungicides, and finally Rhizobium culture/phosphate solubilizing bacteria or follow instructions on the packets.
Fertilizer application:
· Fertilizer requirements depend on the nutrient status of the field, and thus, vary from field to field.
· Therefore, the doses of fertilizers should be determined based on the results of soil test.
· The generally recommended doses for chickpea include 20–30 kg nitrogen (N) and 40–60 kg phosphorus (P) ha-1.
· If soils are low in potassium (K), an application of 17 to 25 kg K ha-1 is recommended. There will be no response to application of K in soils with high levels of available K.
· Total quantities of N, P and K should be given as a basal dose.
· Foliar spray of 2% urea at flowering has been found beneficial in rainfed crops.
Irrigation:
· Chickpea is generally grown as a rainfed crop, but two irrigations, one each at branching and pod filling stages, are recommended for higher yield.
· Higher number of irrigations may lead to excessive vegetative growth in heavy soils.
Weed management:
· Chickpea is a poor competitor with weeds at all stages of growth.
· Pre-emergence herbicides, such as Fluchloralin @ 1 kg a.i. ha-1 or Pendimethalin @ 1.0 to 1.5 kg a.i. ha-1 were found effective in controlling early flush of weeds.
· Mechanical and/or manual weeding can be done where wide row spacing is used.
Plant protection:
· Chickpea being a rich source of protein, is prone to damage by insect-pests and diseases.
· In general, root diseases (fusarium wilt, collar rot and dry root rot) are more prevalent in central and peninsular India, whereas foliar diseases (ascochyta blight, botrytis gray mold) are prevalent.
· Among the insect pests, pod borer (Helicoverpa armigera). is the most severe yield reducer, while bruchids (Callosobruchus chinesis) cause severe damage in storage.
Roguing
· It refers to systematic examination of seed production fields and removal of undesirable plants that may contaminate the seed crop.
· Roguing not only maintains varietal purity but also protects the seed crop from seed-borne diseases.
· The off-type plants, other crop species (with similar seed size), weed plants, parasitic weeds such as Cuscuta spp. and plants infected with seed-borne fungal diseases and viruses should be removed from the seed fields from time to time.
Harvesting and threshing
· The time of harvesting is crucial in maintaining the quality of seeds.
· The crop should be harvested when leaves start to senesce and start shedding, pods turn yellow, plants are dry, and seed feels hard and rattles within the pod.
· After harvest, the plants can be dried in the sun for a few days to ensure that seeds get dried well.
· Threshing can be done using commercially available power threshers.
Seed processing
· The dried seeds are cleaned to remove the undesirable contaminants such as plant parts, soil particles, stones, weed seed, other crop seed, and shriveled, broken, or damaged seed.
· Cleaning and upgrading is based on physical differences between good seed, poor seed and undesirable contaminants.
· The cleaning and grading of seeds is first achieved by winnowing and then through a set of mechanical sieves.
· In addition to air cleaners and aspirators, indented separators, disc separators, gravity separators, spiral separators and drum separators are frequently used.
Seed storage
· The seed must be properly dried before storage.
· The ideal seed moisture level is 10-12% for short-term storage (up to 8 months). After drying, the seed should be either stored in polythene-lined gunny bags or in safe storage structures (metal bins or earthen containers).
· The bags should be kept in a rodent free room and placed on wooden planks (not more than five in a stack) and away from walls to avoid dampness to the seeds.
Seed Certification Standards (Nepal)
Parameter | Foundation Seed | Certified Seed |
Pure seed (min) | 98% | 98% |
Inert matter (max) | 2% | 2% |
Other crop seed (max) | 10/kg | 20/kg |
Germination (min) | 75% | 75% |
Moisture content (max) | 8% | 8% |
14. Yield Potential
· Grain yield: 2.0 to 2.5 t/ha under improved practices
· Seed yield: similar, if roguing and isolation are properly maintained.