Cowpea Biomass Research Articles

Effects of weed control through cowpea intercropping on mayze morphology and yield

Intercropping combined with competitive maize cultivars can reduce the use of herbicides to control weeds. The objective of this work was to evaluate the effects of intercropping cowpea and maize, as well as hand-weeding on maize morphology and yield. The experimental design was in randomized complete blocks, with treatments arranged in split-plots and five replications. The plots consisted of four maize cultivars (BA 8512, BA 9012, EX 4001, EX 6004) and the split-plots consisted of the following treatments: no-weeding; twice hand-weeding (20 and 40 days after sowing); and intercropping with cowpea ('Sempre Verde' cultivar), both maize and cowpea sown at the same time. The variables evaluated were: maize fresh green ears and grain yield; characteristics of internodes, leaves, tassels, ears, grains; plant height and ear insertion height; number of weed plants and species; fresh and dry biomass of weed species and cowpea. Ten weed species were outstanding during the experiment, many of them from the Poaceae family. No interactions were found between weed control method and maize cultivars for most variables evaluated; and plants from hand-weeded split-plots showed superior mean values compared to plants from non-weeded and intercropped split-plots, both not differing from each other. The cowpea was inefficient in controlling weed, reducing the maize yields and not producing any grain. The maize cultivars 'BA 8512' and 'BA 9012 showed the highest mean green ear yield, and the highest grain yield in hand-weeded, no-weeded and intercropped split-plots. On the other hand, the maize cultivar 'EX 6004' showed such high means only in no-weeded and intercropped split-plots. 'EX 4001 presented the worst means in these variables for hand-weeded, no-weeded ant intercropped split-plots.

Simulation study of the competitive ability of erect, semi‐erect and prostrate cowpea (Vigna unguiculata) genotypes

SummaryEcophysiological simulation models provide a quantitative method to predict the effects of management practices, plant characteristics and environmental factors on crop and weed growth and competition. The INTERCOM interplant competition model was parameterised, calibrated by monoculture data for three cowpea (Vigna unguiculata) genotypes that differed in growth habit, common sunflower (Helianthus annuus) and common purslane (Portulaca oleracea), and used to simulate competition of cowpea cover crops with sunflower or purslane. The simulation results were compared with observations from field competition experiments in 2003 and 2004. INTERCOM more accurately simulated actual field data for the competition of cowpea genotypes and sunflower than companion field experiments for the competition of cowpea and purslane. The validated simulation model of cowpea and sunflower at two densities was used to study the effects of cowpea growth habit on final biomass production of cowpea and sunflower. The model suggested that erect growth habit was more competitive than semi‐erect and prostrate growth habit, when cowpea genotypes were grown with sunflower. Cowpea leaf area distribution was important to higher cowpea biomass production, while cowpea height growth was important to reduce sunflower biomass. Our simulation approach is suggested as a method for crop breeders to gauge the likely success of selection for competitive crops before undertaking expensive long‐term breeding experiments.

(316) Simulation Study of the Competitive Ability of Erect, Semi-erect, and Prostrate Cowpea Genotypes

Ecophysiological simulation models provide a quantitative method to predict the effects of management practices, plant characteristics, and environmental factors on crop and weed growth and competition. The INTERCOM interplant competition model was parameterized, calibrated by monoculture data for three cowpea (Vigna unguiculata) genotypes that differed in growth habit, common sunflower (Helianthus annuus), and common purslane (Portulaca oleracea), and used to simulate competition of cowpea cover crops with sunflower or purslane. The simulation results were compared with observations from field competition experiments in 2003 and 2004. INTERCOM did not simulate biomass production and leaf area index (LAI) of cowpea and purslane well, probably due to a lack of published data on purslane physiology. INTERCOM simulated the competition of cowpea genotypes and sunflower accurately. The simulation model of cowpea and sunflower at two densities was used to study the effects of cowpea growth habits on final biomass production of cowpea and sunflower. The model suggested that the erect growth habit was more competitive than the semi-erect and prostrate growth habits when cowpea genotypes were grown with sunflower. Cowpea leaf area distribution was important to higher cowpea biomass production, while cowpea height growth was important to reduce sunflower biomass.

Root‐Knot Nematode Resistant Cowpea Cover Crops in Tomato Production Systems

Root‐knot nematodes, Meloidogyne spp., are serious pests of many crops worldwide. Recent limitations on the use of nematicides have enhanced the need to develop alternative management strategies, including host plant resistance. This study was conducted to determine the effectiveness of nematode‐resistant cowpea [Vigna unguiculata (L.) Walp.] genotypes used as cover crops for suppressing populations of M. incognita (Kofoid and White) Chitwood and M. javanica (Treub) Chitwood and protecting susceptible tomato (Lycopersicon esculentum Mill.) grown in rotation. In six field experiments, susceptible and resistant cowpea was grown to flowering stage and the dried tops incorporated or not incorporated into the soil. These treatments were compared to wet and dry fallowing and were conducted on nematode‐infested and noninfested plots. The experiments were conducted in the Coachella and San Joaquin Valleys, California. Resistance conferred by genes Rk and Rk2 reduced loss of cowpea biomass and M. incognita soil populations and partially suppressed M. javanica compared with susceptible cowpea, but not as effectively as fallow treatments. Incorporation of cowpea tops into the soil promoted tomato growth irrespective of nematode presence. On infested plots, tomato fruit yield was higher following growth and incorporation of resistant cowpea compared with growth and incorporation of susceptible cowpea or nonincorporation of cowpea and fallow treatments. We conclude that root‐knot nematode‐resistant cowpea is an effective cover crop for protecting susceptible vegetable crops grown under irrigation, and its beneficial effects are enhanced by incorporation of its green biomass.

EFFECT OF PLANT DENSITY ON THE YIELD OF SORGHUM–COWPEA AND PEARL MILLET–COWPEA INTERCROPS IN NORTHERN NIGERIA

Three alternate-row intercrop experiments of sorghum (Sorghum bicolor)–cowpea (Vigna unguiculata) and/or millet (Pennisetum glaucum)–cowpea were grown at plant densities of 20 000 to 80 000 plants ha−1 at two locations in northern Nigeria between 1990 and 1992 to examine relations between yield and plant density. These relations were examined using the reciprocals of yield per plant to determine effects of environment, species and genotype on the theoretical maximum yield and optimum plant density. The intercrops were dominated by cereals, and cowpea biomass (BY) and seed yield (SY) were <10% of cereal BY and SY. Cowpea yields decreased as cereal plant density (D) increased, whereas cereal and total intercrop yields increased asymptotically with increasing D. Biomass yield of all intercrops responded to increasing D in a similar manner and the theoretical maximum intercrop BY was 12 290 kg ha−1 in all experiments. The response of SY to D varied among intercrops and was greatest and least with early and late maturing cereals respectively. The optimum D required to produce 90% maximum intercrop BY and SY varied between 15 600 and 30 000 plants ha−1, and 0 (no response to D) and 120 000 plants ha−1 respectively, and was higher for sorghum than for millet intercrops. The implications of these responses for agronomic management and germplasm improvement of cereal–cowpea intercrops are discussed.

Crop yield, C and N balance of three types of cropping systems on an Ultisol in Northern Lampung

Three types of cropping systems, cassava-based intercropping, hedgerow intercropping and legume cover crop rotations, were evaluated in 1994–1997 in Northern Lampung, Sumatra. The purpose of this experiment was to quantify the C and N flows returned within and transported out of plots and crop yields of different cropping systems. Cassava-based systems were not stable and yields declined over time. Intercropping cassava with rice increased cassava fresh tuber weight by 5–48% compared to the monocrop-ping system. The hedgerow intercropping gave lower maize, rice, groundnut and cowpea yields than could be obtained in a crop rotation with legume cover crops. Maize grain yields in the 80–20 rice/maize mixture were about 0.4 Mg ha −1 in the rice — groundnut rotation and about half as much when intercropped with cassava or hedgerows. Rice yields intercropped with cassava or with hedgerows were about 1 Mg ha −1 less in year 2 and 3 than those grown in rotation with groundnut. The rice yield in the first cropping season was only about 1 Mg ha −1, but in the second and third year yields in the rice — legume rotation increased to around 2 and around 3 Mg ha −1, respectively. This increase occurred despite a decline in soil organic matter content. The cassava-based systems removed much more C (7 Mg ha −1 yr-1) than the other systems, while less was returned (about 0.5–2 Mg ha −1) to the soil. In the hedgerow intercropping system about 2.5 Mg C ha −1 yr −1 was returned to the plot as biomass pruning and crop residues and about 1.5 Mg C ha −1 yr −1 was removed from the plot as yield. In the cover crop rotation 2.6 Mg ha −1 yr −1 of C was returned to the plot as crop residues plus Mucuna (only the 2nd year) and Cowpea biomass, and about 1.1 Mg ha −1 yr −1 was removed from the plot. The hedgerow intercropping systems gave an N surplus of about 15–50 kg ha −1 yr −1 returned to the soil; while the balance was 10–20 kg ha −1 yr −1 for the cover crop rotation systems and the cassava-based systems showed a negative N budget of about 60 kg ha −1 yr −1.

Relationship Between Cover Crop Growth, Weed Suppression, and Yield of No-tillage Broccoli (Brassica oleraceae L. var. italica)

In 1997, no-till fall broccoli was grown at the Kentland Agricultural Research Farm (KARF), Blacksburg, Va., and the Beltsville Agricultural Research Center (BARC), Md., to determine supplemental N requirements above the nitrogen contribution from legume in situ mulches. Treatments were tillage systems [CT = conventional tillage, bare soil, tilled prior to transplanting; NT-BS = untilled bare soil; NT-SB = soybean (Glycine max L.) cover crop; and NT-CP = cowpea (Vigna sinensis Endl.) cover crop; and nitrogen fertilizer rates (0, 84, and 168 at KARF, and 0, 56, 112, and 168 kg·ha–1 at BARC). All plots at both sites were treated with recommended herbicides and drip irrigated as needed to supplement rainfall. Dry weight soybean and cowpea biomass was 6.1 and 4.3 at KARF and 4.8 and 3.5 t·ha–1 at BARC. In N-unfertilized plots at both sites, average broccoli yield was higher in NT-SB and NT-CP than CT and NT-BS. The N contribution from the legume mulches was inadequate to meet total crop demand, since N fertilizer applications increased broccoli yield in all tillage treatments, including the legume cover crops (soybean and cowpea). In N-fertilized plots, broccoli yield was similar among tillage treatments at KARF where weed problems were not severe; however, at BARC, yield in CT was higher than in all no-till treatments. Weed pressure was considerably lower in CT than in no-till plots at BARC. Based on these data and other related no-till studies, two conclusions can be drawn: a) no-till systems are a viable option for production of broccoli when weeds are adequately controlled; and b) uniformly distributed, high-residue levels are required for weed suppression when weed pressure is high and herbicides are either ineffective or not applied.

Postemergence Control of Cowpea (Vigna unguiculata) in Cotton (Gossypium hirsutum)

POST control of cowpea in cotton was evaluated in 1990 and 1991. Early POST-directed (EPD) application of fluometuron + MSMA provided 89% cowpea control 2 wk after treatment. Cowpea control 4 wk after the early treatments was similar with fluometuron + MSMA EPD and sequential directed applications of MSMA followed by (fb) MSMA, methazole + MSMA fb cyanazine + MSMA, and fluometuron + MSMA fb cyanazine + MSMA. The average reduction in cowpea biomass 12 wk after planting with these treatments was 93%. MSMA fb MSMA POST-directed was the only treatment with a lint cotton yield similar to that of weed-free cotton. Lint cotton yields with fluometuron + MSMA, methazole + MSMA fb cyanazine + MSMA, and fluometuron + MSMA fb cyanazine + MSMA were similar to those obtained with MSMA fb MSMA.

Plant Mulches in a Reconstructed Chinampa in Tropical Mexico: Effects on Cowpea (Vigna unguiculata) and Potential for Weed Control

ABSTRACT Chinampa agriculture, a variety of raised-field agriculture practised in Mexico for centuries, appears to be highly productive and sustainable. Understanding the effects, mode of action, and potential of aquatically derived mulches, which comprise in part the raised fields, is of practical importance in the design of aquatic and terrestrial sectors of chinampa systems. This study in a reconstructed chinampa in Tabasco, Mexico compares the effects of four mulch treatments (Eichhornia crassipes, Azolla mexicana, Paspalum sp., and an unmulched control), with and without weeding, on the growth and biomass of cowpea (Vigna unguiculata). All three mulches increased cowpea biomass; there was no significant difference among them. With mulch, unweeded plots yielded significantly less crop biomass than weeded plots, whereas in the absence of mulch there was no significant difference between weeded and unweeded treatments. Thus, mulching increased crop biomass, but not by reducing weed interference, and the...