Pigeon pea Cajanus cajan (L.) Millsp.

Climate
Pigeonpea is predominantly a crop of tropical areas mainly cultivated in
semi-arid regions of India. Pigeonpea can be grown between 14°N and 28°N
latitude, with a temperature ranging from 26° to 30°C in the rainy season
(June to October) and 17° to 22°C in the postrainy (November to March)
season. The amount of daily global solar radiation varies from 400 to 430 cal
cm day in the rainy season and 380-430 cal cm-2 day-1 in the postrainy
season. Mean annual rainfall ranges from 600 to 1400 mm, of which 80%-
90% is received in the rainy season. The length of growing season extends
from 120 to 180 days. Isoclimes similar to India exist in western Africa and
southern Sudan, a suitable environment for growing pigeonpea. Pigeonpea is
very sensitive to low radiation at pod development, therefore flowering
during the monsoon and cloudy weather, leads to poor pod formation.
Soils
In India, pigeonpea is cultivated on Entisols, Alfisols, Enceptisols, and
Vertisols. The Entisols found in the alluvial- soil belt of the Indo-Gangetic
region are deep loams, slightly alkaline (pH 7.5-8.5), with about 150-200 mm
available water storage capacity in 2 m of soil. The Vertisols are
characterized by 40-60% clay in the surface soil horizons, pH around 8.0 with
a water holding capacity between 150-300 mm, and the available water in
the top 1.5-2.0 m of soil. Alfisols are neutral in reaction (pH 6.5-7.0) and
relatively shallow with a low-clay content. They are often sandy loam and
can retain about 100 mm available water in the root profile (Reddy and
Virmani 1981). Pigeonpea, being sensitive to water logging, requires a well-
drained soil. It does not grow well in saline soil, but can withstand drought
reasonably well. Responses to lime indicated by increase in shoot growth
and nodulation, have been reported in soils with pH below 5.0 (Edwards
1981).
Cropping Systems
A cropping system is defined as a combination of crops in spaceand time.
The objective of any given system should be to provide the farmer a high
and sustainable level of returns. In agronomic terms , the system makes
efficient use of the basic resources necessary for plant growth (Willey etal
1981 ). Pigeon pea is grown both under sole and intercropping systems .
Sole cropping
Early-maturing (100-120 days) genotypes are grown as a sole crop. These
genotypes have a higher harvest index with an average of 34 % compared to
medium-maturing genotypes at 24 % (Sheldrake and Narayanan 1979 ).
Therefore, from the cropping system point of view, early - maturing
 genotypes are better able to 'complement' by providing an increased
opportunity for a second crop (Willey et a l. 1981 ) . Postrainy season
pigeonpea are also cultivated as a sole crop. This avoids the wet conditions
associated with the rainy season, gives less incidence of pests and d i s
eases, and makes better use of residual soil
moisture . Moreover, postrainy season sole crops were found more efficient
than the rainy season sole crops (Willey et al . 1981 ) .
Pigeonpea
intercropping
Pigeonpea is commonly intercropped with a wide range of crops . In India, it
was estimated that 80 % - 90 % of the pigeonpea were intercropped (Aiyer
1949 ) . Willey eta l. (1981) grouped pigeon pea intercrops into three broad
categories:

 a) With cereals (sorghum, maize , pearl millet, setaria, finger millet , and
rainfed rice).
 b) With legumes (groundnut, cowpea, mung bean, black gram, soybean,
and phaseolus bean ) .
 c) With long-season annuals (caster, cotton, sugarcane, and cassava) .
The advantages of intercrops are (Willey et al. 1981):

 Intercropping confers greater yield stability than sole cropping. For instance,
if one crop fails or grows poorly, the other crop can produce to some extent.
 Under stress conditions, intercropping gives less yield depression than sole
cropping.
 Intercropping may reduce the incidence of weeds. The poor canopy cover
and slow growth of pigeonpea in the early stages makes a sole crop
susceptible to weed. Therefore, a fast-growing intercrop not -only gives a
potential additional yield benefit, but also reduces the need for weeding
(Shetty and Rao 1979).
Land Preparation
Land preparation for pigeonpea requires at least one ploughing during the
dry season followed by 2 or 3 harrowings. The "summer" plowing helps in
minimizing the weed flora and to conserve moisture (Chandra et al. 1983).
Well-drained soils are necessary for good root and nodule development.
Contour beds or a ridge-and-furrow system are useful in preventing water
logging by draining excess surface water,and in preventing soil erosion.
Organic manure may be applied 2-4 weeks before sowing. In acidic soils 2-4 t
ha-1 of lime is incorporated 3-4 weeks before sowing to neutralize the
acidity. In light soils, a basal application of aldrin 5% dust @ 30 kg ha-1
prevents termite infestation (Chandra et al.1983).
Seed Rate and Seed Treatment
The seeding rate of pigeonpea depends on the desired plant density for a
genotype (early, medium or late) , cropping system (pure crop, mixed crop,
or inter crop) , germination rate of seed,and mass of seed.
Seed should be own behind the plough or with the help of seed drill at a row
spacing of 60-75 cm keeping 15-20 cm distance from plant to plant. A seed
rate of 12-15 kg per hectare is sufficient. In mixed cropping seed rate is
adjusted according to the proportion of arhar and companion crops to be
grown. In the intercropping seed rate remains same as for pure crops.
Good quality and pure seed (registered or certified) of the selected variety
should be used from a reliable source. Before sowing, the seed should be
treated with thiram @ 1.5 g kg- 1 of seed plus penta - chloro - nitro benzene
(PCNB) [Brassicol® a.i.1.5 g kg- 1] seed. This w i l l avoid seed rot and
seedling blight diseases (Chandra et.al . 1983). At ICRISAT we recommend
seed treatment with 3 g thiram kg-1 + 3 g carbendazim kg-1 seed.
Sowing Time
In the rainfed and dry areas pigeon pea are sown with the onset of the
monsoon. Earlier sowing gives higher yields in India. When sowing extra -
early and early - maturing varieties in the 1 st fortnight of June , the field is
available for post rainy season crops by the end of November. Therefore ,
sowing should not be delayed beyond June.
The sowing of medium and late-maturing varieties , under rainfed conditions,
should be d o n e during June or July at the onset of the monsoon. This should
be preferably before the 2nd week of July. Late sowing causes considerable
reduction in yield due to photoperiodicity and excessive soil moisture stress
which coincides with the reproductive growth (Chandra et al. 1983). The
postrainy season sowing in India should be done in September. In sowings
later than 15 October , yields drastically decline (Narayanan and Sheldrake
1979).
Methods of Sowing
Three systems of sowings are practiced for pigeon pea. The common is flat
sowing, the other methods are broadbed-and-furrow for extra-early group
and ridge-and-furrow for the late maturity group. The latter two methods are
useful in fields with poor surface drainage and water logging. The raised
beds or ridges also provide better aeration and nodulation in comparison to
the flat sown crop. Experiments at the Indian Agricultural Research Institute,
New Delhi, have shown that pigeonpea sown on a ridge-and-furrow system in
fields prone to water logging gave 30 % more yield compared to flat sowing
(IARI 1971). At ICRISAT a broad bed and furrow system is used for sowing
extra-early genotypes, and ridges-and-furrows are used for medium and late
duration genotyes.
Responses to Nutrients
Responses to general fertilizer applications in pigeonpea are quite meager.
Nitrogen (N): Kulkarni and Panwar (1981) reviewed the studies in India on
the pigeonpea response to N. They concluded the effect was almost
negligible. However, in some situations a starter application of 20-25 kg N
ha-1 was beneficial.
Phosphorus (P): Responses to phosphorus applications have been positive
and in some cases highly significant in pigeonpea (Pathak 1970). Kulkarni
and Panwar (1981) summarized the phosphorus response studies in India.
They concluded that applications of 17-26 kg P ha-1 increased seed yield by
300-600 kg ha-1. Responses of pigeonpea to P fertilization would not be
expected in soils with more than 5 mg kg-1 extractable P by Olsens
bicarbonate extraction; although lower values would not necessarily predict
a response (Johansen 1990).
Potassium (K): Pigeonpea does not respond to potassium chloride
applications unless it is grown on low available potassium soils (Kulkarni and
Panwar 1981).
Rhizobium inoculation: Responses to Rhizobium inoculation have been
inconsistent (Panwar and Misra 1973; Panwar 1975). Increases in grain yield
of pigeonpea inoculated with effective Rhizobium ranged from 19 to 68%
(Kumar Rao 1990).
Zinc (Zn): Most of the pigeonpea cultivars are susceptible to zinc deficiency.
Therefore, foliar applications of 2-4 ppm zinc as 0.5% zinc sulfate with 0.25%
lime have been effective to over-come zinc deficiencies
(Saxena and Singh 1970).
Irrigation
Pigeonpea is largely grown as a rainfed crop, however, it is well established
that flower initiation and pod setting stages are the most crucial to drought
stress . Therefore, irrigation at these stages usually helps the crop (Chandra
et al. 1983). The drought-stress symptoms on pigeon pea are indicated by
the leaves pointing towards the sun at noon (Chauhan et al. 1988).
Excessive moisture is detrimental to pigeon pea. It promotes vegetative
growth and enhances the incidence of Phytophthora and Alternaria blight.
Therefore , irrigation should be given only when the crop experiences
drought stress after flowering and at the pod filling stage (Chandra et al.
1983). Responses to irrigation are more consistent in postrainy season sown
pigeon pea. This crop relies on moisture stored in
the soil profile. Two or three irrigations, 1 mont h after sowing, increased
seed yield by about 150-160% over the nonirrigated control at ICRISAT
Center (Rao et a l . 1 9 8 3 )
Weed Management
Pigeonpea is a slow-growing crop and mostly cultivated during the rainy
season. The crop suffers from early we e d infestation. Therefore, it is
necessary to keep the crop weed-free during the early growth period (4-6
weeks ). The weeds can be controlled mechanically or with chemicals. A
combination of chemical and mechanical control is more economical . At
ICRISAT Center, it was observed that a pre emergence application of
prometryn (Gesgard® or Caparol® a.i. 1.25 kg ha- 1) effectively controlled
the initial weeds .
A hand weeding 3-4 week after sowing is required to remove the late
emerging weeds . When herbicide is not applied, two or three hand weedings
are required from the 1st to 6th week of crop growth. Later the crop will be
able to smother t h e weeds (Chauhan et al. 1988). At ICRISAT, hand
weedings were always found superior to herbicides , but the herbicides were
more economical , hence preferred (Chauhan 1990). The other pre
emergence herbicides effective for pigeonpe a are pendimethalin (Stomp®
a.i. 1.0-1.5 kg ha- 1) or meta chlore (Dual® a.i. 1 kg ha-1). The post
emergence herbicides recommended are flausifop-P butyl (Fusilate® a.i. 0.2-
0.4 kg ha-1) or bentazon (Basagran® a.i. 1.0 kg ha- 1) at 2-4 leaf stage (A.
Ramakrishna, 1992, ICRISAT, personal communication).