PODUCTIVITY OF GRAIN COWPEA (VIGNA UNGUICULATA (L.)WALP.) AS INFLUENCED BY SEASON GENOTYPE INSECT PEST MANAGMEENT AND CROPING SYSTEM IN SOUTH EASTER NIGER

ABSTRACT

The first experiment involved nine improved cowpea genotypes and a local variety. The ten treatments  were  planted  in  two  locations,  namely  the  Research  Farm  of  the  College  of Agriculture, Mgbakwu in Anambra State (060 17ʹN, 070 04ʹE; 83m asl) and the Experimental

Farm of the Federal College of Agriculture, Ishiagu in Ebonyi State (050 58ʹN, 070 34ʹE; 197 m asl), over a period of two years and two seasons per year in each of the two locations. The experiment was spilt-plot arranged in randomized complete block design (RCBD) with three replications. The second experiment was conducted at the DEMACCO Integrated Farms Ltd., Ako, Nike in Enugu State (060  34ʹN, 070  35ʹE; 154 m asl). The experiment consisted of four promising genotypes selected from experiment one and a local variety used as check.  An open pollinated maize variety (ACR9931) was intercropped with the five cowpea genotypes. The maize and cowpea genotypes were sown over a period of two years and two seasons in each year. The experiment was split-split plot arranged in RCBD with three replications. A total number of twenty nine parameters were sampled consisting of  eleven growth, twelve grain  yield  and  six  insect  pest  damage  components.  Data  were  subjected  to analysis  of variance (ANOVA) using the GENSTAT, 2003 edition. Differences among treatment means were compared using F-LSD, while interaction  of  genotype by environment,  genotype by traits and environment  by traits were  computed  using GGE biplot analytical  model. This study revealed the presence of genotype X season, genotype X insect protection and genotype X season X insect protection interaction for experiment one, while experiment two indicated the presence of genotype X season, genotype X cropping system, genotype X spray regime and genotype X season X cropping system X spray regime interaction. Growth, reproductive, grain yield and insect damage components were highly significant in all the environments. Yield and yield components were significantly  higher in early season  than in late season. Similarly, plant population and cowpea biomass were higher in early than late season. Pod length, number of seed per pod, number of branches and  number of internodes were least influenced by the environments due to their high heritability. In all the environments, seed size was significantly higher in IT97K-277-2, IT97K-556-4 and IT93K-452-1, than the rest genotypes, while IT84S-2246-4  and  IT90K-82-2 consistently expressed significantly lower seed size. The local variety produced significantly higher seed size than all the test genotypes when sprayed with insecticide in late season. The genotypes IT90K-277-2, IT97K-556-4 and local  variety  exhibited  dual-purpose  (grain  and  fodder)  characteristics,  while  the  rest genotypes were purely grain type. Most of the dual-purpose cowpeas are both indeterminate and long duration. The short growth duration and higher mean grain yield made IT93K-452-1 the best grain type cowpea because it combined these qualities with tolerance to most post flowering  pests. The genotype  IT93K-452-1  also produced  reasonable  grain  yield in late season without chemical spray. IT98K-131-2 was an outstanding medium maturing genotype combining superior grain yield attribute with tolerance to both pre-and-post flowering pests in all the environments. Furthermore, this  variety also produced satisfactory grain yield in late  season  without  insecticide  application.  Genotype  IT97K-556-4  on  the  other  hand, harboured the highest population of most pests sampled in all the environments. This study further showed that thrips, Maruca, pod sucking bugs and bruchids were the most prevalent insect pests of cowpea in south eastern Nigeria, while aphids and Ootheca were the minor pests. Application of insecticides once each at flower bud initiation, full bloom and podding significantly reduced insect pest population and increased grain yield of cowpea significantly. Improved cowpea genotypes recorded significantly higher grain yield than the local check in all the environments. Medium to late maturing genotypes were better adapted to late season while  early maturing  genotypes  performed  well in both  seasons.  Bruchids,  Maruca,  pod sucking bugs and thrips were more abundant in late season than early season while aphids and  Ootheca  population  were more  widespread  in early  season  than late season.  Brown seeded cowpea  genotype  consistently  harboured  lower infestation  by bruchids  than white seeded types. This study also showed that insecticide treatment targeted at the critical growth stages  especially  at 50  percent  podding  and early  sowing  significantly  reduced  bruchids damage on stored cowpea seed. Grainyield loss assessment was negligible in early season for all the genotypes while in late season it was 100 percent for local variety, 34 percent for best yielding medium maturing genotype (IT98K-131-2)  and 30 percent for best yielding  early maturing genotype (IT93K-452-1). Percentage reduction in insect population when 3 sprays were applied relative to zero spray for aphids, bruchids, Maruca, Ootheca, pod sucking bugs and thrips are 121 percent, 240 percent, 174 percent, 45 percent, 38 percent and 270 percent respectively. Intercropping reduced dry fodder yield in early season by 22 percent and in late season by 41 percent. On the other hand, intercropping did not significantly reduce number of branches, internodes number, number of leaves, number  of nodules, plant population, and root length. Meanwhile, peduncle length was significantly reduced by intercropping in both early  and late  season  but  varied  widely  among  the  genotypes  tested,  with  local  cowpea variety being most affected. Peduncle  length in cowpea was obviously  sensitive  to stress imposed  by intercropping  particularly  in late  season  and  could  be  used  as an index  for determining cowpea  cultivars adapted to intercropping  environment.  Intercropping  in both seasons significantly reduced yield and yield components in cowpea but more in late  than early season. Consequently, intercropping reduced grain yield in early season by 14 percent while in late season it reduced it by 25 percent. Also, intercropping in early season reduced days to maturity but did not affect 50 percent bloom and pod filling duration. However, in comparison with early season, all the genotypes in late season flowered and matured earlier, while on the contrary they took longer days to fill their pods. In both seasons, sole cropping generally  produced  higher  grain  yield  than  intercropping  when  sprayed  with  insecticide. Conversely, cowpea grain yield in intercropping were generally higher than yields from sole cropping   when   no   insecticide   was   applied,   suggesting   less   insect   damage   under intercropping.  Early maturing genotypes produced significantly  higher grain yield in early and  late  seasons  and  in  both  sole  and  intercropping,  while  medium  and  late  maturing genotypes expressed their highest yield potentials in sole cropping in late season. Also, in late season, intercropping significantly reduced the population of bruchids, pod sucking bugs and thrips  but  did  not  affect  the  population  of  the  rest  insect  pests.  Highest  grain  yield components were realized in genotypes grown in intercropping with two sprays while in sole cropping  early maturing  genotypes  required  two sprays  while  medium  and late maturing genotypes  required  three  sprays  to produce  the highest  grain  yield.  Late season  planting reduced the population of aphids, Maruca and Ootheca by 122 percent, 183 percent, and 47 percent respectively, while early season sowing reduced the population levels of pod sucking bugs by 47 percent and thrips by 104 percent. Intercropping reduced the population of aphids, bruchids, pod sucking bugs and thrips by 40 percent, 9 percent, 8 percent, and 100 percent respectively.  Meanwhile,  intercropping  increased  the infestation  of Maruca  by 9 percent while   Ootheca   was   unaffected   by   cropping   system.   Intercropping   combination   of ACR9931/IT98K-131-2 had positive effects on maize through the production of significantly higher yield and yield components of maize, while ACR9931/Local combination depressed components of maize yields. We found improved medium maturing, indeterminate cowpea cultivar with long peduncle length as most suitable for use in intercropping with maize in South-eastern  Nigeria.  Maize  performed  better  under  intercropping  than sole cropping  in early than in late season, in 2009 than  2010. The yield reduction in maize from cropping system, season and year effects was caused by decline in cob length, cob weight, number of cobs per plot, seed weight, 100 seed weight and harvest index, and not by number of plant stands. This revealed that maize productivity is more influenced by these traits.

CHAPTER ONE

INTRODUCTION

Cowpea is cultivated on at least 12.5 million hectares, with an annual production of over 3 million tonnes world wide. Cowpea is widely distributed throughout the tropics, but Central and West Africa accounts for over 64 percent of the area.  In West Africa, a substantial part of the cowpea production comes from the drier regions of northern  Nigeria (Singh et al., 1997). Mortimore (1980) reported that by the 1960s and 1970s there was a long established cowpea trade network, linking the producing areas in northern Nigeria with the major centers of demand in the south. In other words, cowpea remains predominantly a crop of drier areas. Quin (1997) noted that as further advances are made in crop improvement and management, there will be opportunities  for commercial  production  of  cowpea in longer season, wetter agro-ecologies.  Furthermore,  Kormawa  et  al.  (2002)  observed  that  if  suitably  adapted improved varieties of cowpea along with  appropriate integrated management  packages are identified the crop’s production area will expand rapidly to wetter regions.

Cowpea is consumed by humans in many forms; the young leaves, green pods, and green seeds are used as vegetables; dry seeds are used in various food preparations; and the haulms including pod walls are fed to livestock as nutritious supplement to cereal  fodder (Barrett

1987).  Nigeria  is the  largest  consumer  of cowpea  in the  world  (Nnanyelugo  et al.,  1985; McWatters et al., 1990). Nnayelugo et al. (1997) stated that cowpea consumption in southeastern Nigeria has increased in frequency and quantity by 150 percent and has also  reduced severe malnutrition in children by 70 – 100 percent. The image of cowpea has improved and it is being introduced into children’s diets at earlier ages in both rural and urban areas, and that almost all the dry cowpea seeds consumed in southern Nigeria are brought in from the northern part of the country. Similarly, Uguru (2008) is in support of this observation. Although southeastern Nigeria has favorable weather and soil that can sustain commercial grain cowpea production, the region unfortunately accounted for only about 0.57 percent of the total grain cowpea production and

0.38 percent of the total area cultivated in Nigeria in 2007 (APS, 2008).

The bulk of the diet of rural and urban poor African people consists of starchy food made from cassava,  yam, cocoyam,  millet,  sorghum,  and maize.  The addition  of even  a small amount of cowpea ensures the nutritional balance of the diet and enhances the protein quality by the synergistic effect of high protein and high lysine from cowpea and high methionine and high energy from the cereals. The nutritious and balanced diet ensures good health and enables the body to resist infectious diseases and slow down their development (Nielsen et al.,  1993).  It  has  been  found  that  HIV/AIDs  patients  placed  on  daily  cowpea  diets experienced significant boost in their immunity level thus prolonging their lifespan (Clark, 2005).  Similarly, Carper (1988) pointed out that a cup of cooked, dry beans every day should lower  the  low-density  lipid  cholesterol,  regulate  blood  sugar  and  insulin,  lower  blood pressure, regulate the bowels, and prevent gastrointestinal  troubles, even  hemorrhoids  and cancer  of  the  gut.  Furthermore,  individuals  with  type  1  diabetes  can  cut  their  insulin requirements by 38 percent if they increase their bean intake a cup (about 184 g) a day. It is estimated that cowpea supplies about 40 percent of the daily protein requirements to most of the people in Nigeria (Muleba et al., 1997).

Insect pest damage is a major constraint  to cowpea production  in Nigeria (Raheja,  1976; Amatobi, 1994). Insect pest attack in cowpea often leads to total yield loss (Singh and Allen, 1980; Jackai et al., 1985). Use of insecticides improves the yield of cowpea ten fold (Singh and Allen, 1980; Parh, 1993). Jackai (1983) and Adalla (1994) observed that in parts of Asia the effects of misuse of insecticide  is already being felt as more cases  of  resistance  and damage to ecosystems  are being reported yearly. Edwards (1993)  warned that unless this trend is reversed in Nigeria, we can expect the same problems of the insecticide treadmill that characterizes  agricultural  systems  in  the  developed  world.  To  increase  the  efficiency  of insecticides  and  reduce  overuse,  chemical  application  should  be  carefully  managed  to coincide with critical growth stages where pest pressure is high (Alghali, 1992).  In order to reduce  insect  damage,  increase  cowpea  productivity,  and  control  indiscriminate  use  of insecticides,  it is important  to  conduct  studies  to determine  the  growth  stages  at  which minimum  use of insecticide  is advisable.  Moreover,  application  of insecticides  should be integrated  with  other  cultural  practices  to increase  effectiveness  and  reduce  over  use  of insecticides  (Kamara  et al.,  2009).  There  is therefore  the need  to develop  a robust  pest management package for cowpea production in Nigeria especially in a pest endemic region like  southeastern  Nigeria.  Afun  et  al.  (1991)  stated  that  cost  effectiveness  of  minimum insecticide  applications  in  combination  with  other  cultural  practices  show  a  50  percent reduction in production cost.

Planting date has been identified as an important component of integrated pest management practices  ((Hall,  1992).  It  has  been  suggested  that  adjusting  planting  dates  could  cause asynchrony between crops and insect pests (Pedigo, 1989). Karungi et al. (2000) reported that planting early in the season reduced aphids, thrips and  pod-sucking  bug’s infestation  but increased Maruca infestation in Uganda. The reduction in aphids, thrips and pod bugs was attributed  to  lower  population  in  the  early season,  which  could  build  up  as  the  season progresses and cause more damage to lately planted cowpea. It was suggested that differences in planting dates could be explored in different agro-ecologies as it may have some potential in influencing the incidence of various insect pests (Taylor, 1978; Akingbohungbe, 1982).

Intercropping has long been known to be a major component of integrated pest management (IPM)  (Olufajo  and Singh,  2002).   Singh  and Emechebe  (1998)  found  that  intercropped cowpea gave higher grain yields than yields from the sole crop  when  no insecticide  was applied, indicating less insect damage under intercropping. Blade et al. (1997) noted that the local cowpea varieties are highly adapted to intercropping systems than improved varieties but they have a very low harvest index.  However, Singh and Emechebe (1998) identified good performance of a number of IITA improved varieties under both sole and intercropping. These cultural practices when combined with the use of insecticides and host-plant resistance are probably the most effective measure against some of the cowpea pests, and could be used as cost effective components of integrated pest management package (Javaid et al., 2005). However, there is no properly packaged IPM program for cowpea production in southeastern Nigeria yet. This is because the individual components have to be developed first before they can be consolidated into a management package. This is part of what this experiment seeks to establish.

Despite the high potential benefits of cowpea in Nigeria, the yield levels are very low which range from 240-300kg/ha (Rachie, 1985). Meanwhile, when the crop is grown in pure stand with required inputs, improved varieties, and appropriate management practices, yield as high as 4 tonne per hectare has been reported (Rachie, 1985; Huxley  and Summerfield,  1976; Singh, et al., 2002).

Although different categories of improved cowpea varieties are available on the shelf in the research  stations  of IITA, there is limited  study on the productivity  of these  varieties  in Southeastern  Nigeria with respect to their performance  or responses when  exposed to the

entire  pest  complex  under  natural  field  infestation  (either  sprayed  or  not  sprayed  with insecticides)  and at different  planting dates. The identification  of cultivar(s)  that  produce reasonable yield without insecticidal protection can be a low input approach to solving the problem of yield constraints in cowpea occasioned by high population of insect pests in the region,  and  also  enhance  the  promotion  of  sound  ecologically  and  economically  viable cowpea  production  options.  Furthermore,  the  integration  of   these  selected  low  input genotypes  with  appropriate  sowing  date  and  cropping  system  will  even  result  in  more sustainable cowpea production system through better IPM strategy. Such IPM package would be compatible with resource poor cowpea farmers and equally promote organically produced cowpea crop. On the other hand, identification of responsive cowpea cultivars to insecticidal treatments will certainly catalyze the commercialization of cowpea production enterprise by medium  to  large  scale  farmers.  The  pest  problem  in  cowpea  is  complex  and  requires diversified  efforts.  Any single  effort  will be a slow and frustrating  process  (B.B. Singh, personal communication).

The general objective of this research is to assess the productivity of ten cowpea genotypes under varying spray regimes, locations, seasons, and cropping system in the moist savanna of southeastern Nigeria agro-ecology.

The specific objectives are to:

1.        determine the effects of insecticide treatment on cowpea insect pests infestation and growth and yield of cowpea genotypes;

2.        determine the effects of time of seeding on cowpea insect pests infestation and growth and yield of cowpea genotypes;

3.        determine  the  effects  of  cropping  system  on  cowpea  insect  pests  infestation  and growth and yield of cowpea genotypes; and

4.        establish  appropriate  combination  of  insecticide  treatment,  time  of  seeding  and cropping  system  on  insect  pests  management  and  growth  and  yield  of  cowpea genotypes.

₦5,000.00 – DOWNLOAD FULL PROJECT DOWNLOAD FULL PROJECT Added to cart

---

---

---

---

Related Project Topics :