Competition in a rice - cowpea intercrop as affected by nitrogen fertilizer and plant population

Abstract

The increased productivity or yield advantage provided by intercropping is attributed to a better use of resources by crops grown in mixtures, as compared to the same species grown in sole stands. In an intercropping system with upland rice and cowpea, the intra and inter-competition was quantified, as affected by plant population density and rate of nitrogen. Reductions in number of panicles per rice plant and number of grains per panicle were obtained with high density in both sole and mixture rice populations. Increasing nitrogen rate did not affect yield and yield components in both populations, but number and weight of pods per plant of cowpea in sole stands increased. Land equivalent ratios exceeding unity were obtained, indicating an improved resource use by the crop mixture. Relative crowding coefficient and aggressivity indices showed cowpea to be the dominant crop, with rice being dominated. Nitrogen utilization efficiency was high with intercrops, but was generally poor in stands of high population density. Key words: aggressivity index, land equivalent ratio, nitrogen utilization efficiency, relative crowding coefficient COMPETIÇÃO EM UMA CULTURA CONSORCIADA DE ARROZ-GUANDU EM FUNÇÃO DO FERTILIZANTE NITROGENADO E DA DENSIDADE POPULACIONAL DE PLANTASRESUMO: O aumento em produtividade devido a plantios consorciados é atribuído ao melhor uso dos recursos presentes pelas plantas em desenvolvimento conjunto, em comparação às mesmas espécies crescendo em dosséis separados. Em um sistema consorciado de arroz e guandu quantificou-se as inter-e intra competições em relação à densidade populacional e taxa de aplicação de nitrogênio. Reduções significativas do número de panículas por planta de arroz e número de grãos por panícula foram observados para alta densidade, tanto para culturas solteira de arroz como em populações mistas. O aumento das doses de nitrogênio não afetou a produção e os componentes de produção em ambos os sistemas, ao passo que o número e peso de vagens por planta do guandu aumentaram em culturas solteiras. Foram obtidas razões de área equivalente maiores que a unidade, mostrando melhoria no uso da terra nas culturas mistas. O coeficiente relativo de superpopulação e os índices de agressividade mostraram que o guandu é dominante e o arroz dominado. A eficiência do uso de nitrogênio foi alta nas culturas consorciadas, mas em geral baixa para populações de alta densidade. Palavras-chave: índice de agrssividade, razão de área equivalente, eficiência do fertilizante, coeficiente relativo de superpopulação

Evaluation of Sorghum-Cowpea Intercrop Productivity in Savanna Agro-ecology using Competition Indices

“…Results showed positive aggressivity for sorghum at 2S:1C and 1S:1C planting patterns while it proved less competitive and was dominated by cowpea at 1S:2C planting pattern. This agreed with the findings of Oroka and Omoregie (2007) who obtained higher aggressivity in cowpea over rice at higher population densities. The competitive ratio which measures the degree with which one crop competes with the other showed that sorghum had higher competitive indices than cowpea in all the planting patterns except 1S:2C arrangement.…”

Effect of Supplementing Inorganic Fertilizer with OrganicFertilizer on Growth and Yield of Rice-Cowpea Mixed Crop

“…The results have showed that mixed cropping of rice and cowpea under CCD and CD is economically efficient, as indicated by the LER values in both 2009 and 2010. Other studies (Okereke and Ayama, 1992;Okonji et al, 2007;Oroka and Omoregie, 2007) have reported increased biological efficiency of rice-cowpea intercrops indicated by LER >1. The yield advantage of the ricecowpea mixed cropping may be attributed to more efficient light utilization in the combination of tall rice with short cowpea.…”

“…In addition, the harvest of cowpea during the reproductive stage (early heading) of rice could have contributed to the higher productivity of rice under the mixed cropping system, as a result of less plant-plant interaction and competition for resources after the harvest of cowpea. Oroka and Omoregie (2007) also reported an increase in panicle number per hill of rice intercropped with cowpea over their sole rice crops. The reduction in rice grain yield under the mixed cropping system compared with the grain yield of rice under the sole cropping system was due to the higher population of rice plants under the sole than under the mixed cropping system.…”

“…Few studies have focused on rice-cowpea mixed cropping under nitrogen fertilizer and different plant populations (Okereke and Ayama, 1992;Oroka and Omoregie, 2007). Considering the negative effect of continuous use of inorganic fertilizer alone for intensive crop production and the positive effects of organic fertilizers on the soil, the objective of this experiment is to assess the productivity of rice and cowpea under cow dung manure alone or in combination with inorganic fertilizer on the growth and yield of the component crops under the mixed cropping system.…”

Effect of maize intercrop plant densities on yield and β-carotene contents of orange-fleshed sweetpotatoes

“…Similarly, in the potato-maize mixture, increase in maize plant population resulted in a decline in tuber yield (Ebwongu et al, 2001), due to reduced light interception by the potato hence the reduced photosynthetic activities of the crop. Apart from light, crops grown in association compete for water and nutrients in the soil (Oroka and Omoregie, 2007), and high plant densities result in increased competition for these resources, consequently causing low yields (Zamir et al, 2011).…”