Response Of Cowpea Research Articles

Reproductive Responses of Cowpea to Heat Stress: Genotypic Differences in Tolerance to Heat at Flowering1

The effect of high temperature on ability of cowpea [Vigna unguiculata (L.) Walp.] to set pods was investigated under field conditions and in controlled environments. During hot weather in the Imperial Valley, Calif., the cowpea strains TVu 4552, PI 204647, and ‘Prima’ produced substantial numbers of pods, while 55 other strains produced no or few pods, even though they produced numerous open flowers. Studies in growth chambers demonstrated that TVu 4552 has greater tolerance to high night and high day temperatures at flowering than the California cultivar, ‘California Blackeye No. 5’ (CBS), whereas Prima is intermediate. Susceptibility to high temperatures was associated with low pollen viability and indehischent anthers for CB5 and with anther indehiscence for Prima. Artificial pollination demonstrated that pistil viability of all three genotypes was not significantly affected by high temperature. Thus, the flower abscission observed with CB5 and Prima at high temperatures was mainly caused by male sterility. In addition, substantial levels of embryo abortion were observed with CB5 and Prima at high day temperatures. Apparently, Imperial Valley provides a suitable field environment during the summer for screening cowpeas for heat tolerance. This environment is presently being used to screen the segregating populations from crosses designed to incorporate the heat tolerance of TVu 4552 and Prima into genetic backgrounds suitable for the tropics and subtropics.

Cowpea Response to Row Width, Density, and Irrigation1

AbstractThe interrelationships among row width, plant density, and irrigation are not well understood for cowpea [Vigna unguiculata (L.) Walp.], as shown by previous conflicting results describing the sensitivity of cowpea to drought. Two experiments, a three factor central composite, second order design in incomplete blocks, and a two factor split plot randomized block design, were used to quantify the yield responses of ‘California No. 5’ cowpea established at five row widths (25 to 125 cm), five plant densities (4 to 34 plants m−2), and five (0 to 200 cm) and two levels of irrigation at planting. Cowpea was grown on sandy clay loam soils (fine, mixed thermic families of Aridic and Torrertic Paleustolls) on the research farm in Lubbock and the Slab farm in Hereford, Tex. Seed yield was very dependent on irrigation, increasing linearly from 635 kg ha−1 to 2043 kg ha−1 at the Lubbock site without evidence of diminishing returns. At the second site more water was available from rainfall and irrigation and yields were greater (2837 kg ha−1). Highest yields were obtained with the combination of wide rows and high plant density while lowest yields resulted with high plant density in narrow rows. Of the components of seed yield, pod number per plant and seed number per pod were important regulators of seed yield, while seed size remained reasonably constant. Seed yield and harvest index results suggested that, in narrow rows, the more uniformly spaced plants explored the complete soil volume earlier, extracting more of the available soil water during vegetative growth, and leaving less available for reproductive growth than in wide rows. This restriction on reproductive development in narrow rows was accentuated most when plant densities were highest. Our study shows the need to examine plant interactions before management recommendations can be firmly established.

Pod and grain yields from intercropping maize andVigna unguiculata(L.) Walp. in Nigeria

SUMMARYField experiments were conducted at the International Institute for Tropical Agriculture, Ibadan, Nigeria, during two cropping seasons, with two cultivars of climbing cow peas (Vigna unguiculata(L.) Walp. subspeciessesquipedalis) cv. FARV-13 and TVU-1209. The work investigated their yields when intercropped with maize, which served as live support.The results showed that there were varietal differences in the cow-pea response to method of planting. Under the intercropped systems, highest dry-matter yield was obtained when TVU-1209 was planted on the same hill with maize while similar yields were obtained with FARV-13 planted in alternate hills with maize. TVU-1209 did not increase maize lodging except when planted in alternate hills with maize, but FARV-13 significantly increased maize lodging under all planting methods. Consequently, FARV-13 reduced maize yields more than TVU-1209.Neither pod length nor pod weight was affected by the planting. Highest yields from both cow pea and maize combined were realized from TVU-1209 planted between rows of maize. The yield of FARV-13 cow pea intercropped with maize did not show any advantage due to intercropping over sole crop of each.

Growth and yield responses of cowpea and maize to inoculation withGlomus mosseae in sterilized soil under field conditions

The effects of inoculation of cowpea and maize withGlomus mosseae and sowing into field soil fumigated with formalin are reported. Root infection was significantly, though temporarily, decreased and grain yield increased, by sterilization. Inoculation increased root infection, shoot yields, P contents and grain yield.

Responses of cow pea (Vigna unguiculata) varieties and their hybrids to variation in day and night temperature regimes

SUMMARYThe effects of each of four contrasting combinations of two day (30, 26°C) and two night (24, 19°C) temperatures were studied on four cowpea varieties and their F1 hybrids. Early vegetative development was enhanced by the higher day, higher night temperature and flowering occurred first in plants receiving this treatment. The hybrids showed marked heterosis for leaf area but not for time to flowering. The ten genotypes studied showed correlated responses to increases in night temperature and differed in the degree of their response. The extent of the response (or stability) of varieties was often determined by the character values in the environment with the highest yield and heterotic hybrids were the least stable. Grain yield was highest in the lower day temperature environments but there was variation between genotypes in whether this occurred at the lower or higher night temperature. The pattern of responses shown by hybrids agreed with those of their parents indicating that stability was an inherited character. The results confirmed and extended those in earlier studies and emphasised the importance of a greater understanding of the nature of responses to the environment in selecting new varieties.

Varietal Response of Cowpea to a Range of Densities in a Forest Zone

SUMMARYCowpea cvs Ife Brown and New Era were sown at a wide range of densities in 1976 and 1977 (early season) at Ibadan in the rainforest zone of Nigeria. In 1977 (late season), the experiment was modified and Ife Brown and Vita 5 were used. All the cultivars were indeterminate. Grain yields were higher at lower densities, especially in 1977 (late season). Numbers of leaves, branches and pods were also inversely related to density, but there were differences between varieties in flowering, branching and leaf and pod production.

Response of cowpea (Vigna unguiculata) to inoculation with VA-mycorrhizal fungi and to rock phosphate fertilization in some unsterilized Nigerian soils

The effects on cowpea of inoculation with vesicular-arbuscular (VA) mycorrhizal fungi and rock phosphate (RP) fertilization were studied in pots using Alagba and Araromi series soils and in the field on Alagba, Apomu and Egbeda series soils. Inoculation of the plants with VA-mycorrhizal fungi caused very rapid infection of the roots. A higher per cent mycorrhizal infection was maintained during subsequent plant growth in the field. RP application reduced the degree of infection without affecting plant growth in the field and in pot experiments. Nodulation, nitrogen fixation and utilization of RP were increased by inoculation with mycorrhizal fungi in the pot experiments but not in the field experiments. In the pot experiments, inoculated plants supplied with RP flowered earlier, and took up more phosphorus than either inoculated plants without RP or uninoculated plants. The largest response to inoculation in terms of shoot dry matter, nodule yield and nitrogen content of shoots was obtained in Alagba soil under both pot and field conditions.

Yield Losses in Cowpea Following Leafhopper Damage1

Yield response of cowpea, Vigna unguiculata L. (Walp.), to infestation by a leafhopper Empoasca dolichi (Paoli) was studied in the field and greenhouse by using resistant and susceptible cultivars. Field studies indicated that in the absence of insecticidal protection during the preflowering growth stage, susceptible cultivars TVu 2045 and TVu 76 were severely damaged with a yield loss of more than 40%. Resistant cultivars TVu 1190E, TVu 662, TVu 3629, and TVu 4557 had a foliar damage rating of 3.0 and indicated no significant yield loss. In greenhouse studies, the susceptible cultivar TVu 76 was significantly reduced in plant height, pods per plant, and grain yield.

Influence of Soil Organic Matter on Cowpea's Response to N Fertilizer

AbstractThere are divergent views on N application to legumes, especially cowpea. Results of various investigations in the tropics, especially Nigeria, have indicated either no response or a significant response to about 20 kg N/ ha. In Nigeria, a starter N is usually recommended irrespective of the cropping history of the field. As a result of these conflicting reports three field and one greenhouse experiments were carried out over a period of 4 years to investigate the effect of different levels of N, soil organic matter (O.M.), and split application of N on grain yield and performance of cowpea. Ife‐Brown, an improved variety of cowpea, was used as the test crop. The soils of the fields used were moderately to strongly leached luvisols, derived from metamorphic and igneous basement complex rocks under forest vegetation. The experimental design for each field experiment was a randomized, complete‐block design, while the greenhouse investigations was laid out in a split plot design. Cowpea was grown on fields having different cropping histories and levels of O.M. with various levels of N including no nitrogen as control. Cowpeas responded to N fertilizer; however, the level of O.M. affected the response. On soils having 0.5% O.M., grain yield was increased from 800 kg on the check to 1,850 kg dry grain per hectare, where 20 kg N/ha was applied, whereas on soils with 2% or more O.M. there was no constant response to N fertilizer.In the greenhouse, N fertilizer did not effect the time of flowering and pod initiation of cowpea but the total number of flowers and pods were significantly affected. When 33.6 kg N/ha was applied at planting or split into two equal applications applied 2 and 4 weeks after planting, there was a significant increase in dry matter accumulation but low grain yield. In the latter treatment the cowpea fixed 33.07 mg N per pot compared with 40.10 mg N when 33.6 kg N/ha was applied at planting. The treatment that produced the highest grain yield fixed the lowest N. Application of N at planting and 2 weeks after planting depressed nodule number up till the 4th week, but 10 weeks the highest number of nodules was observed on cowpeas from the plots where N was applied at planting. It is concluded, therefore, that starter N should be used in soils having less than 2% O.M. Such starter N should be applied not later than 2 weeks after planting. Time of N application affects nodulation and N fixation.

Effect of Indole-3-Acetic Acid (IAA) on Biochemical Responses of Cowpea (<i>Vigna unguiculata</i> (L.) Walp) Var. Bari Fellon-1

The biochemical responses of Cowpea to IAA treatments (foliar spray) with different concentrations (20 ppm, 40 ppm, 60 ppm and 80 ppm) were studied. Biochemical parameters such as leaf pigments, moisture, ash, crude fiber, calorie, protein, fat, carbohydrate and nitrogen free extract (NFE) contents in seeds of Cowpea were studied in the experiment. Different biochemical parameters responded differently following IAA treatments. Highest protein content (22.7%) and ash content (4.2%) were recorded from the seeds of the plants treated with 80 ppm IAA. Highest carbohydrate content (60.8%) and calorie content were recorded from the seeds of the plants treated with 60 ppm IAA. Moisture content was decreased due to all IAA treatments. Fat, crude fiber and NFE content of seeds also found to be varied with different treatments. Out of all the treatments, the best stimulation was found for 60 ppm IAA treatment. The results of the present work also indicate that an appropriate concentration of IAA can be fruitfully utilized to produce better quality of seeds and leaf pigments of Cowpea. Key words: Auxins; Biochemical response; IAA treatment; Cowpea DOI: http://dx.doi.org/10.3329/bjsir.v46i1.8110 Bangladesh J. Sci. Ind. Res. 46(1), 77-82, 2011

The Effect of Temperature upon the Local Lesion Response of Cowpea Inoculated with Cucumber Virus I

The use of cowpea, Vigna sinensis Savi, as a local lesion, semiquantitative assay host for cucumber virus I was described in some detail in an earlier paper.2 Sometime before this Price3 described the cowpea local lesion response. It was felt that additional work concerning the effect of temperature upon the development of local lesions might reveal greater consistent differences than those reported previously.2 With this in view, cowpeas, var. Black, were grown at 160, 200, 240, and 280 C under winter light conditions, using the same standard conditions for growth, age of plants, inoculation techniques, choice of inoculum, and strain as described by Sill and Walker.2 All plants were started at 200 C and then were moved to the critical temperatures one week prior to inoculation. Five trials were completed, lesion averages per trial being based upon 40 primary leaves on 20 plants. The work was done in part at the University of Wisconsin, Madison, and was completed at Kansas State College, Manhattan.