Four experiments were used for the studies. Experiment 1 studied the performance of six pigeonpea genotypes namely ICPL 87 and ICP 161 of Short – duration types, ICPL 85063, ICP 7120 and ICPL 87119 of medium-duration types and Nsukka Local of long-duration type in intercropped systems with two maize genotypes in 2005 and 2006 cropping seasons at the Research Farm of the Department of Crop Science, University of Nigeria Nsukka. The two maize genotypes were hybrid maize and open pollinated maize. There were twenty treatments consisting of six sole pigeonpea genotypes, six pigeonpea/hybrid maize mixtures, six pigeonpea/open pollinated maize mixtures and two sole maize treatments comprising of sole hybrid maize and sole open pollinated maize. The field experiment was a factorial laid out in a randomized complete block design (RCBD, with three replications. Both intercrop and sole crop treatments of the crop genotypes were maintained at 40,000 plants ha-1. The representative leaf samples of the pigeonpea genotypes were analyzed for N, P, K and Ca contents at the flowering stage. The intercropping efficiencies of the pigeonpea/Maize mixtures were analyzed using the land equivalent ratio (LER) technique and benefit/cost ratio analysis. Correlation analyses on grain yield, growth and yield parameters were carried out on the pigeonpea data. The 2006 pigeonpea plants were assessed for ratoonability in 2007. Experiment 2 was a two-phased storage experiment on the seeds of the pigeonpea genotypes to assess the status of field-to-store insect pest infestation. Actellic dust (Pirimophos-methyl) was applied at zero, half dosage and full dosage levels (0.0g, 0.5g and 1.0g) per treatment in the first phase. Callosobruchus maculatus adults were introduced in the second phase to assess the residual effect of the actellic dust on the C.maculatus storage pest. Experiment 3 involved assessment of susceptibility of the seeds of the six pigeonpea genotypes to C maculatus under storage conditions. Evaluation of the pigeonpea genotypes seed for hardness was done in a completely randomized design (CRD) with three replications. Susceptibility index (SI) analysis was carried out to evaluate the resistance of the genotype seeds to the pest. Proximate analysis was carried out on representative seed samples of the pigeonpea genotypes. Experiment 4 concerned analysis of antinutritional factors and enzyme inhibitor contents of tannin, phytate, trypsin and chymortrypsin in the pigeonpea genotype seeds in a completely randomized design (CRD) with three replications. Data obtained in all the experiments were analysed using Genstat (3) discovery package of statistical analysis, and means were separated for significant differences using least significant difference (LSD) procedure at 5% level of probability. The result of experiment 1 showed that maize intercropping with pipeonpea significantly (P<0.05) reduced leaf number, leaf, stem and root dry matter weights, stem girth, nitrogen leaf contents and grain yield in pigeaonpea. The grain yield of ICRISAT pigeonpea genotypes were superior to that of Nsukka local genotype. The pigeonpea genotypes differed significantly in their number of primary branches, pod bearing stem length, leaf and stem dry matter weights, insect pests damaged seeds, one thousand seed weight and total grain yield. Pigeonpea ratooning in the second year was significantly higher in the long-duration pigeonpea genotype compared with the short– and medium–duration ICRISAT genotypes. The yield of pigeonpea ratoon crops on the average was 60% of the main crop. Land equivalent ratio (LER) values greater than one (>1.0) were obtained in all pigeonpea/maize mixtures. Mixtures also gave greater monetary returns than the sole of either pigeonpea or maize. The grain yield in pigeonpea had significant positive correlation with leaf, pod and seed counts per plant and with the pod bearing stem length and dry matter yield of leaf, stem and root fractions. The result of experiment 2 showed that there was no field–to–store infestation in the pigenonpeas. The residual activity of actellic dust significantly reduced F1 count and final insect mortality count of C. maculatus under storage. The result of experiment 3 showed that the pigeonpea genotypes differed significantly in their susceptibility to C maculatus with ICPL 161, ICPL 87 and ICPL 85063 being in resistant category and Nsukka Local, ICP 7120 and ICPL 87119 being in moderately resistant seed category. The pigeonpea genotype seeds also differed significantly in their physical hardness. The result of experiment 4 showed that the pigeonpea genotypes had moderate but significantly different anti-nutritional and enzyme inhibitor contents.
TABLE OF CONTENTS
Title page … … … … … … … … … … i
Certification … … … … … … … … … … ii
Dedication … … … … … … … … … iii
Acknowledgement … … … … … … … … iv
Published articles from the work … … … … … … … v
Abstract … … … … … … … … … vi
Table of contents … … … … … … … … … viii
List of Tables … … … … … … … … … x
CHAPTER 1: INTRODUCTION … … … … … … … 1
CHPATER 2: LITERATURE REVIEW
Reasons for intercropping practices … … … … … … 8
Legumes in intercropping systems … … … … … … 10
Cereal/legume intercropping production systems … … … … … 11
Land Equivalent Ratio (LER). .. … … … … … … … 13
Cost/Benefit ratio analysis …. … … … … … … … 15
Crop Genotype … … … … … … … … … 15
Phenology of Pigeonpea … … … … … … … … 17
Maize Production … … … … … … … … 18
Pigeonpea production … … … … … … … … 19
Diseases and pests of pigeonpea … … … … … … … 23
Antinutritional factors in pigeonpea. … … … … … … 25
Plant Tissue analysis … … … … … …. … … … 27
CHAPTER 3: MATERIALS AND METHODS
Experiment 1: Assessment of six pigeonpea genotypes under two late maize intercropping systems. … … … … …. …. …. … 28
Assessment of intercropping efficiency … … … … 33
Benefit/Cost ratio analysis. … … … … … … 33
Experiment 2: Assessment of field-to-store insect pests infestation on six pigeonpea genotype seeds and the residual effect of actellic dust on C. maculatus
insect pests. … …. …. …. … … …. … 33
Experiment 3: Susceptibility of six pigeonpea genotype seeds to Callosobruchus
maculatus storage pest. … … … … … … 35
- Seed hardness test.. …. …. …. … … … 35
Plant material chemical analyses. … … … … … 37
- Proximate Analysis of pigeonpea seed. … … … … 37
- Mineral element analysis in plant … … … 39
Experiment 4: Antinutritional Factors Assessment in the seeds of six phigeonpea
genotypes. … … … … … … … … 40
CHAPTER 4: RESULTS
Experiment 1: … … … … … … … … … 42
Experiment 2: … … … … … … … … … 95
Experiment 3: … … … … … … … … … 100
Experiment 4: … … … … … … … … … 103
CHAPTER 5: DISCUSSION
Experiment 1: … … … … … … … … … 105
Chemical Analysis … … … … … … … … … 121
Experiment 2: … … … … … … … … … 122
Experiment 3: … … … … … … … … … 124
CHAPTER 6: SUMMARY AND CONCLUSIONS … … … 127
References … … … … … … … … … 131
Appendix I … … … … … … … … … 147
Appendix II … … … … … … … … … 151
Pigeonpea (Cajanus cajan (L.) Millsp) belongs to a group of leguminous crops called pulses. The pulse legumes, are those species harvested traditionally for their mature seeds, and are a major source of dietary proteins and feed products throughout the world. They are especially important as human food in those regions where animal proteins are scarce (Norton et al., 1985). Their introduction into a feeding regime based on cereals or tubers balances the latter and combats protein deficiency linked malnutrition, which is frequent in the developing countries, especially in West Africa (Borget 1992).
According to Reddy et al., (1993), pigeonpea is an important grain legume crop of rainfed agriculture in the semi-arid tropics. The India sub-continent, eastern Africa, and central America, in that order, are the worlds three main pigeonpea-producing regions. Pigeonpea is cultivated in more than 25 tropical and sub-tropical countries, either as a sole crop or intermixed with such cereals as sorghum ( Sorghum bicolour (L.) Moench), Pearl Millet (Pennisetum glaucum (L.) R. Br,), maize (Zea mays L.) or with legumes such as groundnut (Arachis hypogea L.). It is one of the mandate crops of International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) which has released improved genotypes to farmers (Guy et al., 2001), and holds about 13,544 accessions (ICRISAT Newsletter Oct., 2003).
Consultative Group on International Agricultural Reseach (CGIAR) (2005) report indicated that in 2005, world production of pigeonpea was about 3.5 million metric tons. Africa accounted for 317,862 metric tons, and Asia for 3 million tons. It also reported that the area harvested to pigeonpea in 2005 was 4.5 million hectares globally. India alone accounted for about 76.5% of this figure. Other producers are Sub-Saharan Africa and Latin America and the Caribbean. The report further indicated that pigeonpea ranks sixth in area and production in comparison with other grain legumes such as beans, peas and chickpeas.
Pigeonpea is an erect shrub, a leguminous perennial that is managed in agricultural systems as an annual or biennial (Snapp et al., 2003). It may reach 4m in height depending on the genotype, but is usually about 1.5m. It is woody at the base of the plant and the side branches are generally erect (Morton, 1976). The vertical taproot is deep and extensive, reaching depths of 1-2m with multiple branches (Anderson et al., 2001; Sheldrake and Naranyanan, 1979). Maturity ranges from about 90 to 280 days from planting. Genotypes tend to be extremely sensitive to photoperiod and temperature, which can greatly alter phenology, height, and productivity (Reddy, 1990). Growth habit ranges from erect with acutely angled branches (30 degrees or less) to more spreading types with branch angles as large as 60 degrees (Whiteman et al., 1985). Some cultivars tend to produce long primary branches with leaves along their entire length and fruits concentrating in the terminal one-third or one-half of each branch. Some genotypes branch very little and produce flowering recemes directly on the main axis. Trifoliate leaves are arranged spirally in a 2/5 phyllotaxy and inflorescences are 4-12 cm long, borne either terminally or at axillary nodes. They further reported that flowering can be diffuse over the whole plant spreading throughout a long period, or synchronous, depending upon the genotype and on the photoperiod and temperature regime. Flowers are about 2.5 cm long with four calyx lobes. The Petal colour varies from yellow to red or purple, with some tinged, striped or mottled with red purple. The stigma is terminal, and the ovary and base of style are hairy. Fruits are flattened pods with diagonal depressions between each of the two to nine locules, and are up to 10 cm long, beaked and often hairy. Pod wall colour can be green, brown, dark maroon to dark purple or blotched, with a greasy or waxy surface when immature, and the pods are straight to sickle shaped, 5-10 cm wide, glabrous and glandular (Bogdan, 1977). Fruits contain between two and nine seeds per pod and do not shatter. The seeds are orbicular, oval to flattened, sometimes speckled. The hilum is small and white. Seed size varies from 6-28g per 100 seeds (Purseglove, 1974).
Pigeonpea has a wide range of products, including the dried seed primarily used as dahl (a processed, dehulled, split seed). The green pod and immature seed are used as green vegetables while the leaf and stem are used for fodder and for soil improvement, with the dry stem used as fuel. It makes an outstanding contribution to home production systems by enhancing both human nutrition and soil nutrient content (Snapp et al., 2003). Faris et al. , (1987) further reported that in addition to protein, pigeonpea provides carbohydrates and five fold higher levels of vitamin A and C than greenpea (Pisum sativum L.).
According to Whiteman et al., (1985), the crop is most commonly grown for its dry, split seed (dhal), which has a protein concentration of approximately 20-25%; but the immature seed is also eaten as green vegetable. Dry seed and the by-products of dhal manufacture, as well as leaf and pod-wall residues after harvest, can provide suitable feed for ruminants, which may also graze the standing crop (Whiteman et al., 1985). The potential for wider consumption and commercialisation of pigeonpea is indicated by an expanding global market for pigeonpea products (Jones et al., 2002). The export potential of split pigeonpea (dhal) is high as it is exported to India, the Middle East, Europe and North America. By promoting processing and widening the scope of utilization of pigeonpea for local consumption and export, both production and productivity can be substantially increased (Tuwafe et al., 1994).
In Nigeria, Tabo et al., (1995) reported that the grains are prepared into various dishes such as yam porridge meal and maize/pigeonpea porridge “ayalaya” for human consumption. It is also used as a soup thickener. The grains substitute for cowpea in “akara” balls, can be cooked as “moi moi”, and fermented to produce “Dawadawa” for food seasoning.
Snapp et al., (2003) reported that in the Caribbean region, there is persistent demand for vegetable pods and peas, both canned fresh. Indian and Afro-Caribbean communities around the globe offer new markets for dahl. In addition to food uses, pigeonpea is reported to have outstanding soil amelioration and conservation properties. The growth habit facilitates soil protection, as the canopy continues to expand for 4 months in the dry season after other crops are harvested when living and senescent pigeonpea leaves may be the only source of cover in semi –arid agroecosystems. According to Rao et al., (2002), pigeonpea leaves are reported to have characteristics that promote soil fertility benefits, such as low lignin levels and high nitrogen content. Pigeonpea nodulates with a wide range of Rhizobium strains and consistently fixes 20 to 140 kg ha-1N in infertile soil (Anderson et al., 2001). The vigorous root system explores a large soil volume and recycles nutrients from deep in the profile (Johanson, 1990). Further, pigeonpea root exudates have the unusual ability to solubilize iron-bound phosphorus from some soil types (Ae et al., 1990).
Among pulse crops, pigeonpea is unique, apart from some lupin species, in its utilization also as an annual crop as well as its use in agroforestry and shifting cultivation systems and as a source of forage for livestock. Whiteman, et al., (1985) reported that because of its great diversity of habit and use in quite contrasting production systems, greater differences exist in growth and development among genotypes adapted to the various production systems than exists in many other crops.
Maize (Zea mays L.) belongs to the family Poacea and according to IITA (2007), it is the most important cereal crop in sub-Saharan Africa and, with rice and wheat, is one of the three most important cereal crops in the world. IITA (2007) further reported that maize is high yielding, easy to process, readily digested, and cheaper than other cereals.
Maize is an annual monoecious plant with erect cylindrical stem of 0.5-5.0m high and 2-7cm thick. The leaves are 8-21 in number but usually about 14 are arranged one on each stem node. They include a leaf sheath which firmly embraces the stem, and a broad linear leaf blade with a small ligule where it is attached to the stem. It has advantitious roots developed from the lowest nodes of the stem immediately above the mesocotyl, which are close together and about 2.5cm below the soil surface. The roots penetrate down to a depth of 30-40cm and spreading to a diameter of 10-20cm.
In industrialized countries, maize is largely used as livestock feed and as raw material for industrial products, while in developing countries like in Nigeria, it is mainly used for human consumption. In sub-Saharan Africa, maize is a staple food for an estimated 50% of the population, and important source of carbohydrate, protein, iron, vitamin B, and minerals. Africans consume maize as a starchy base in a wide variety of porridges, pastes, grits, and beer. Green maize (fresh on the cob) is eaten parched, baked, roasted or boiled, playing an important role in filling the hunger gap after the dry season. Maize has been in the diet of Nigerians for centuries as a subsistence crop but has now risen to a commercial crop on which many agro-based industries depend on as raw material (Iken and Amusa 2004) . According to Alabi and Esobhawan (2006), most cultivation of maize in Nigeria, unlike in the temperate countries, is in intercropping. Therefore intercropping research involving maize will be of immense importance to the traditional farmer who also intercrop pigeonpea mostly.
Andrew and Kassam (1976), defined intercropping as growing two or more crops simultaneously on the same field. Crop intensification is in both time and space dimensions.There is intercrop competition during all or part of crop growth. Farmers manage more than one crop at a time in the field. Cropping system was also defined as the cropping patterns used on a farm and interaction with farm resources, other farm enterprises and available technology which determine their make-up. Andraw and Kassam (1976) also defined cropping pattern as the yearly sequence and spatial arrangement of crops and fallow on a given area, and sole cropping as where one crop variety is grown alone in pure stand at the normal density. Ratoon cropping is the maintenance of crop regrowth from living stumps after harvest. It is a form of continuous cropping. Intercropping and ratoon cropping systems are all practised with pigeonpea and have practical benefits.
In intercropping, crops can be mixed in different proportions. In additive series the component crops are mixed at the recommended sole crop population densities (Baker, 1979). In replacement or substitutive mixture series, the combined densities of the crops maintain the same population pressure as in sole crops. Improved ground cover achieved by an additive intercrop contributes to reduced soil erosion and hence better retention of soil fertility particularly when spreading type cultivars are used as the shorter component (Fukai and Trenbath 1993). Fukai and Trenbath (1993) suggested that the most productive intercrops are additive ones involving components differing greatly in growth duration. Maximum output should be obtained with sequences of “high yielding” crops in compatible mixtures. In practice, this pattern has evolved in relation to the traditional resources at low and intermediate inputs circumstances where several crops are planted and harvested in mixtures at different times. Intercropping research involving pigeonpea and maize has not been common and will be of great importance and benefit considering their economic values to the farmer. Much of the intercropping work done in ICRISAT, India, had mostly been with pigeonpea and millet (Penisetum glaucum L.) and sorghum (Sorghum bicolar L). It would be very desirable to evaluate those newly released pigeonpeas of differing growth parterns and duration with maize (Zea mays) under Nigerian condition in the humid tropical lowland conditions of Nsukka where maize is more popular and more widely grown than millet or sorghum.
Seed yields obtained from pigeonpeas in traditional farming systems are reportedly low (Whiteman et al., 1985). It is also noted that the major production system of intercropping of late-maturing pigeonpeas necessarily restricts the yield potential in the farmers′ fields. Snapp et al., (2003) reported that research attention to pigeonpea remains limited. Australia and India are two of the few countries to have made significant investments in pigeonpea research along with the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).
Midmore (1993) reported that suitable land areas for food production remain fixed or are diminishing, yet farmers and agronomists are faced with the task of increasing production. Successful crop mixtures extend the sharing of available resources over time and space, exploiting variation between component crops in such characteristics as rate of canopy development, final canopy width and height, photosynthetic adaptation of canopies to irradiance conditions and rooting depth.
Much studies involving the ICRISAT short- and medium-duration varieties in mixture have not been done under the Nigerian conditions. Rao and Willey (1980) had earlier indicated that the slow establishing and later-maturing pigeonpea combined well with earlier cereals and legumes to give very large yield advantage as measured by the Land Equivalent Ratio (LER) under the Indian conditions.
Pigeonpea production is penetrating the Nigerian traditional farming system. However, not much work has been done across the ecological zones using improved short-duration and medium-duration varieties to replace poor yielding, tall and long-duration varieties currently used by the farmers. Tabo, et al., (1995) reported that farmers asked for high yielding, shorter duration varieties with softer, faster cooking grains, and varieties suitable for alley cropping.
Since there is limited land and other production resources at the disposal of the traditional farmer, the approach to improve the crop yields per unit area through simple, adaptable and sustainable technologies such as intercropping with improved genotypes, will be of great advantage. Giller et al., (1997) had stated that proposed interventions in soil fertility management must generate cropping systems that are productive, sustainable and economically attractive for small holder subsistence farmers. Jagtap and Adamu (2003) reported that farmers may rapidly adopt improved technologies that cost little or nothing or one within their reach and that can contribute to increasing their productivity. Kimani (1991) reported that improved long (9 months), medium (6 months) and short (4 months) duration pigeonpea cultivars have been developed and released by ICRISAT. Although these varieties showed high yield potential under research environment, their performance under farmer condition are yet poorly documented.
There is a need to adapt and adopt the newly developed pigeonpea genotypes into the popular farming systems of the local farmers. The opportunity offered by the compatibility of legume/cereal intercropping requires a planned study using the newly released ICRISAT genotypes in a pigeonpea/maize intercropping system research in Nigeria. There is little or no published literature information of ICRISAT pigeonpea genotypes intercropped with maize under Nsukka derived savannah agro-ecology condition.
The present study has the following objectives:
- To assess the growth and yield of five improved and one local pigeonpea genotypes in mixtures with two maize genotypes under late season cropping.
- To assess the intercropping efficiency over sole cropping using LER and cost/benefit ratio.
iii. To evaluate the general morphological and agronomic attributes of the pigeonpea genotypes that might have relevance to competitive advantage of each genotype in mixture with maize.
- To study the insect pest problems in the field and to achieve efficient post-harvest storage.