Pigeon pea Breeding- Crop Improvement kharif

Pigeon pea Breeding- Crop Improvement kharif, origen, floral biology, breeding methods, varieties

1. Crop Improvement – I (Kharif)
Dr. Pratibha Bisen
Assistant Professor
College of Agriculture, Balaghat
Pigeonpea [Cajanus cajan (L.) Millspaugh]
Pigeonpea (Cajanus cajan (L.) Millsp.) is an important legume crop in the tropics and subtropics
also and plays an important role in food and nutritional security due to rich in protein (23-27%), minerals
and vitamins (esp. vitamin B). The crop is grown for multiple uses (food, fodder and fuel) in the semi-arid
regions of India and Africa (Nene & Sheila, 1990). It is also grown in different cropping systems as it
enriches the soil with nitrogen and phosphorus.
Centre of origin and Distribution
The pigeonpea name was first reported from plants used in Barbados. Once seed of this crop were
considered very important there as pigeon feed (Plukenet 1692). Pigeonpea has originated in India from
its progenitor C. cajanifolius and later spread to the Africa and Australia (Van der Maesen, 1980).
The alternate hypothesis suggesting Africa as the centre of origin does not seem to be viable as
only one wild relative C. kerstingii is reported to occur in West Africa. In addition, C. scarabaeoides has
also been found in Africa, but spread is restricted to the coastal areas only. Consequently, van der Maesen
(1980) proposed Africa as the secondary centre of origin (Saxena, 2010). Therefore, the most acceptable
route of dispersion describes that the immigrants moved the crop up from India to East Africa, then the
route followed to Egypt (via Nile valley), West Africa and finally to the America (Odeny, 2007; Kassa et
al., 2012). Fifteen wild species have been reported in Australia also.

Chromosome Number
The first report demonstrating the eleven pairs of homologous chromosomes (n=11) in pigeonpea
was documented by Roy (1933). Somatic chromosome number of pigeonpea was reported to be 2n=22
(Naithani, 1941). The wild relatives of pigeonpea also contain similar number of chromosomes except in
African species C. kertsingii, which exhibited a different chromosome count of 2n = 32 (Gill and
Hussaini 1986).

Family, cultivated & wild species

2. The genus Cajanus belongs to the sub-tribe Cajaninae, tribe Phaseoleae, sub-family
Papilionoideae and family Fabaceae. Based on biosystematics, Van der Maesen (1986) merged the
species of Atylosia with Cajanus. It postulated that C. cajan originated from this species through selection
for desirable traits like size and vigour of the plant, non-shattering pods and larger seed size. Cultivated
pigeonpea, however, differs from C. cajanifolius in flower morphology, pod size and colour, seed
strophiole and 100 seed weight (Mallikarjuna et al., 2012).
Pigeonpea is a diploid and often cross-pollinated crop with a genome size of 858 Mbp
(Greilhuber and Obermayer, 1998). As per the revised concept of gene pool (GP) proposed by Smartt
(1990) and referred as second order of GP-I, this may also include C. cajanifolius which is freely
crossable with C. cajan and produces fertile hybrids. Other nine Cajanus species (C. lineatus, C.
lanceolatus, C. laticepalus, C. albicans, C. reticulatus, C. sericeus, C. scarabaeoides, C . trinervius, C.
acutifolius) that are cross compatible with C. cajan form the secondary gene pool while, remaining 21
species, which do not cross with C. cajan are placed in tertiary genepool (Remanandan, 1990) and require
sophisticated biotechnological techniques for their exploitation in crop improvement. The genus has 11
related genera such as Rhynchosia Lour., Dunbaria W. A., Eriosema (DC.) Reichenb; Flemingia and
Carissoa (Mallikarjuna et al., 2011) The genus Cajanus has 32 species. Out of these, 18 species are
endemic to Asia, 13 to Australia, and one to West Africa (Van der Maesen, 1990). C. cajanifolius, C.
lineatus, C. sericeus, C. scarabaeoides, C. albicans, and C. trinervius are of Indian origin and C.
reticulatus (var. grandiflorus), C. convertiflorus and C. latisepalous of Australian origin.

Floral Biology

The pigeonpea flowers, borne in short racemes, are predominantly yellow in color. The
peduncles of pigeonpea are 1–8 cm long. Pedicels are thin and covered with hairs. Bracts are 1–4 mm
long and their margins curve inwards to form a boat like structure. The calyx tube is campanulate with
numerous glandular hairs with bulbous bases. The tube is dorsally gibbous and the corolla is highly
zygomorphic, papilionaceous, and generally yellow in color. The petals are imbricate in the bud. The
standard petal (vexillum flag) is erect and spreading more or less orbicular with clawed base. The wing
petals are obovate with a straight upper margin, clawed base, asymmetrically biauriculate.



Flower of pigeon pea

Keel petals are boat-shaped, clawed and dorsally split, and ventrally split near the base. Stamens
are 10, diadelphous (9+1), flattening towards the base, tapering towards the top, and geniculate near the
base. The anthers are ellipsoid, dorsifixed, and light or dark yellow in color. Of the 10 stamens, four have

3. short filaments and six, including the odd posterior one, have long filaments. The odd stamen has a
groove for the passage of nectar that is secreted from the base of the filaments. The long stamens are
antisepalous and the short ones antipetalous. In general, the pollen grains in the “short” stamens are larger
than those in the “long” stamens. Generally the stigma of a mature flower bud is surrounded by anthers
which dehisce a day before the opening of flower. On a bright sunny day, anthesis starts in the early
morning, peaks at 9-10 AM and continues till 4 PM. The duration of flower opening varies from 6 to 36
hours depending upon the climate and environmental conditions.


Emasculation and Pollination

To breed new varieties, or transfer specific trait into the adapted cultivars, artificial hybridization
is undertaken. Since pigeonpea is a perennial plant, its flowering generally continues until about 80% of
the pods are mature. This provides an extended period in which to complete the targeted crosses in a
breeding program. Pigeonpea is protogynous and the stigma becomes receptive 68 hours before anthesis
and stigma receptivity is maintained even 20 hours post anthesis.

• The first step in hybridization is to identify appropriate parental lines and purify them by
removing obvious off-types and mixtures. It is always better to acquire genetically pure seed for
hybridization. Based on the characteristics of the parents and mating scheme, specific cross combinations
should be identified.
• The land for the crossing block should always be selected near an irrigation source and be
protected from stray animals. The parental lines should be planted at row-to-row spacing of 75–100 cm.
This will allow a person to sit comfortably between the two rows while making crosses. The plant-to-
plant spacing is kept at 30–50 cm.
• Each parental row should be labeled properly and purified by removing off-type plants, if
any. Within each row of female parents each plant should be given an identification number. This will
help in keeping an effective crossing record.
• Emasculation of male fertile buds in the female rows is carried out with a fine sharply-
pointed forceps. The other materials required for hybridization include about 3˝ long pieces of thick
colored cotton thread for easy identification of crossed buds and a notebook or card to record the day-to-
day progress of hybridization.
• It has been observed that the crossing success is higher if the early developing floral
buds are chosen on the female plant for crossing. Generally, each bunch contains 5–6 floral buds of
different sizes. Of these, only two buds should be retained for emasculation and the remaining very young
or over-grown buds are removed before emasculation.
• For emasculation, tightly closed buds, approximately two thirds the size of mature buds,
are selected. Such buds have a bright yellow corolla without any greenish hue.



Emasculation in pigeon pea flower

4. • The selected bud is firmly held between thumb and the middle finger with the index
finger used to support the bud from behind in such a way that the curved side of the standard petal faces
the crosser.
• The sepal covering the keel is removed first then the corolla is forced open by inserting
one of the tips of the forceps at the base of the keel and moving it upward to the distal end of the bud.
This bud will open with a slight pressure of the supporting index finger and thumb exposing its stamen
column.
• At this point, the anther filaments are carefully held with forceps without touching the
stigma and they are removed from the stamen column with gentle sideways (left or right) movement of
the hand. It is essential to ensure that no anther is retained inside the dissected bud.
• This emasculated bud is now ready for pollination.
• The selected pollinator bud should be fully grown but still closed.
• For pollination, the entire stamen column is removed with the pair of forceps and the
pollen-bearing anthers are brushed on the stigma of the emasculated bud to effect fertilization.
• The pollinating buds harvested from the male parent should be kept in a labeled petriplate
with moist filter paper in the base.
• Tying a piece of colored thread around the pedicle of the pollinated bud will help in
distinguishing the hand-pollinated bud on the female plant.
• If the female plants are limited in number and more crosses need to be made, then more
than one cross can be made on a single plant. In such a situation, different colored threads can be used to
identify different crosses.
• The success of crossing is determined primarily by the skill of the pollinator and
environment. It has been observed that success in hybridization is low on a cloudy or foggy day.
• For successful inter-specific crosses it is advisable to use the wild species as male
parents. It has been observed that when the wild species are used as female parent, the rate of success is
less than 1% and in the reciprocal crosses the success rate is about 10%.

Tagging

The flowers are tagged just after bagging. They are attached to the inflorescence or to the flower
with the help of a thread. The following may be recorded on the tag with pencil.
• Date of emasculation
• Date of pollination
• Parentage
• No. of flowers emasculate


Breeding objectives
Breeding for higher yield / area/ time is the first and foremost objective in pigeonpea
irrespective of maturity groups. Since large G-E interaction is experienced for phenology and
reproductive growth of pigeonpea, stability in productivity also assumes utmost importance. Some
other factors that influence stability in production include stress imposed by diseases such as wilt, sterility
mosaic, Phytophthora and Alternaria blights and insect pests such as pod borers and pod fly. Therefore,
incorporation of resistance to these biotic agents in the variety is also indispensable. Since pigeonpea is
cultivated mostly under rainfed condition, it also encounters extremes of moisture stress.

 Growth habit and plant type
These are most important parameters for realizing high yields and stability under intercropping systems.
The characteristically adapted pigeonpea cultivars for intercropping are those with non-determinate
growth, spreading or semi-spreading plant type with more number of primary/secondary/tertiary branches
and long fruit-bearing lengths. The compact genotypes do not perform well in intercrops due to their poor

5. plasticity and biomass production. The present day medium maturing semi-spreading cultivars are being
grown successfully under both pure as well as intercropping.

 Pod and seed size
These are very important yield contributing traits and their breeding is rather easy due to high heritability
and easy identification of desirable segregants. In pigeonpea germplasm, there is a vast range of
variability for both pod size (2–9 seeds/pod) and seed size (4–26 g/100 seeds). Therefore, pigeonpea
breeders, over a period of time, have worked out a combination of 4–6 seeds/pod plus seed size of 12–14
g/100 seeds for breeding high yielding cultivars with market-preferred traits.

 High-protein
Most of the subsistence farming families depends on pulses for their protein requirements. However due
increasing population pressure, reducing farm holdings and increasing cost of inputs, the per capita
protein availability is on rapid decline. The high protein (up to 28%) lines derived from various inter-
specific crosses can provide some relief to this problem.

 Breeding for waterlogging tolerant cultivars
Temporary waterlogging (WL) poses a serious threat to pigeonpea productivity, especially in high water-
holding capacity soils. The annual productivity losses in India are estimated at 25–30% on 1.1 m ha
waterlogged pigeonpea area (Choudhary et al. 2011). Under waterlogged situations, the shortage of
oxygen in the soil adversely affects growth and development of the plants.

 Breeding for disease resistant cultivars
In pigeonpea, two diseases namely Fusarium wilt (FW) and sterility mosaic (SM) are considered very
important. These diseases cause heavy losses in almost all the pigeonpea growing areas. However,
availability of resistant sources (donors) and reliable screening technology have resulted in a number of
cultivars having joint FW and SM resistance.

 Earliness & photo insensitivity
Prevailing cultivars of pigeonpea cannot fit in preceding or proceeding cropping systems due to extended
duration and photo‐sensitivity. Hence, photo‐insensitivity coupled with earliness is the desired trait of
interest for the breeders. In this regard, super‐early pigeonpea with defined traits of earliness,
photo‐insensitivity, impressive per wheat–pulse cropping pattern as well as rice fallows emerged as new
intervener in pigeonpea breeding.

Ideotype

The term ‘ideotype’ is used to label the set of characteristics that would seem best to suit an
organism to its environment. Plant ideotype breeding intends to deliver crop genotypes that are suitable
for modern farming practices and it involves improvement in key traits such as harvest index and
mechanical harvesting. Several plant attributes including plant height, number of branches, pods per plant
and synchronous maturity collectively contribute to improved plant architecture. Besides, short-duration
cultivars are important in light of the need for increasing cropping efficiency of farming system.
The two plant types Determinate (DT) and Indeterminate (IDT) exist in pigeonpea (Mir et al., 2013).
Short-statured DT types cease their growth once they reach flowering. Whereas, vigorous IDT types
continue the growth even after flowering. Though IDT is a dominant trait preferred by pigeonpea
growers, continuous flowering followed by non-synchronous harvesting draws the attention on DT type
breeding. High initial vigour, tolerance to drought & water logging and ease in mechanical harvesting in
DT type are found advantageous over IDT type. Further, faster manipulation in growth habit and
flowering time will be favored in this climate smart breeding era. Pigeon Pea ideotype requires:

6.  Semi dwarf plant type (1.5-1.8m) for mechanized plant protection
 Open canopy with determinacy
 Non-cluster pod bearing
 Long fruiting branches for high yield
 Middle and top bearing
 Spreading type for intercropping in south and central India
 Compact plant type for intercropping in northern India

Important national and international research centres
There are 13,771 accessions of pigeonpea conserved at International Crops Research Institute for
the SemiArid Tropics (ICRISAT), Patancheru, Andhra Pradesh, India (Upadahyay et al., 2007). ICRISAT
has developed a composite collection of pigeonpea containing 1000 accessions representative of the
diversity of all germplasm collection. The International breeding research conduct on pigeon pea in
International Institute of Tropical Agriculture (IITA), Ibaban, Nigeria also.
In the national gene bank at National Bureau of Plant Genetic Resources (NBPGR) 10,189
accessions of Indian collections are conserved. In addition, NBPGR has also repatriated 5,748 accessions
to national gene bank. The extensive use of few parents in pigeonpea improvement programmes has led to
the narrowing down of genetic base of the cultivated varieties which defeats the purpose of collecting a
large number of germplasm.

Plant genetic resources
Plant genetic resources are an invaluable source of genes and gene complexes for yield and
several biotic and abiotic factors and provide raw materials for further genetic improvement. Therefore,
the collection of pigeonpea germplasm and its proper characterization and evaluation, conservation and
utilization in improvement programmes assume great significance especially in view of climate change.
Problems that remain are the difficulty of maintaining pigeonpea as a population in the same
constitution as when collected, although the majority of lines are not very heterozygous. Infraspecific
classification is difficult because of the variation in habit when grown in different seasons and at different
locations, but demand for this classification does not appear to be heavy.

Important breeding methods
Some crops do not fit neatly in either the self or cross pollinated categories. Usually the amount
of crosspollination exceeds that of the normally self pollinated crops, yet does not reach that of the
normally cross pollinated. In these crops breeding procedures commonly used for self pollinated crops are
modified to accommodate the larger amount of crosspollination. Pigeonpea, a grain legume crop grown
for food in tropical and subtropical regions, averages about 20% crosspollination, but may range from 5 to
40% with different cultivars and environments. The methods of breeding pigeonpea are similar to those
utilized in breeding other selfpollinated crops:
(1) Introduction based on germplasm collections,
(2) Selection
(3) Hybridization
(4) Development of F1 hybrid cultivars
(5) Mutation breeding has contributed mutant genes for specific characters.

Varieties
For Madhya Pradesh recommended varieties are JKM 189, TJT 501, JKM 7, TT 401, BSMR175,
ICPL 87119, BSMR 736, JA 4, UPAS 120, BDN 2, KM 7, C 11, NPWR 15, BSMR 730

Hybrid seed production technology

7. Pigeonpea is unique among the pulses as its floral morphology allows partial cross-pollination.
International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in 1974 started breeding
hybrids using the natural out-crossing. As a first step a program was launched for breeding a male sterility
system that could be used in breeding hybrids; and a genetic male sterility (GMS) system, controlled by a
single recessive gene (ms1ms1), was identified (Reddy et al., 1978). This GMS was used to develop
hybrid technology to assess the extent of hybrid vigor and ability of out-crossing in seed production on
the male sterile plants. The first ever pigeonpea hybrid ICPH 8 performed very well in the multi-location
trials, coordinated trials, and in the farmers’ fields with mean standard heterosis of 25–35%, was released
in 1991 for cultivation (Saxena et al., 1992). This was followed by the release of five other GMS based
hybrids. Despite the yield advantages of 25–40%, these hybrids could not be commercialized due to seed
production difficulties (Saxena et al., 2006). This valuable experience indicated that in pigeonpea
sufficient heterosis is available and seed production issues can be tackled economically if the GMS
system could be replaced with cytoplasmic genic male sterility (CGMS) system.
Any hybrid technology that is based on CGMS system, works on three different plant genetic
systems and therefore it is popularly known as a “three line hybrid system.” This essentially includes
male-sterile (A- line); its maintainer (B- line), and restorer (R- line). This male sterility system was found
ideal for hybrid breeding and was designated as A4 CMS. The genetics of fertility restoration of
A4 cytoplasm was studied and two dominant genes were found controlling the fertility of the hybrids .
GTH1 is the world's first CMS (A2 cytoplasm) based hybrid developed at SDAU (Sardarkrushinagar
Dantiwada Agricultural University), S K Nagar, Gujarat in 2004. But, this hybrid failed to gain its
stakehold due to the problems associated with the stability of fertility restoration caused by high G x E
interactions. Thus, world's first commercial pigeonpea hybrid is ICPH 2671(A4) produced by crossing
ICPA 2043 with ICPR 2671 released in 2010 by the government of Madhya Pradesh which had 47%
yield advantage over national check Maruti. After the success of hybrid ICPH 2671 in Madhya Pradesh,
two more medium duration hybrids with high yield potential were released in India. In 2012, ICPH 2740
was released for cultivation in Andhra Pradesh (Saxena and Tikle, 2015); while the third hybrid ICPH
3762 was released in Odisha in 2014 (Saxena et al., 2014a).

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