39. Cassava/legume intercropping with contrasting cassava cultivars. Part I
1. Competition between component crops under three intercropping conditions.
Field Crops Research, 29, 1992, pp. 113-133
In this paper, cassava/pigeonpea intercropping was examined under two growing conditions in which the competitive ability of pigeonpea was different. Cassava/soybean intercropping was examined in only one situation.
In the work reported in this series of two papers, various cassava cultivars were intercropped with either of two legume species to identify physiological and morphological characteristics of cassava which are suitable for different types of intercropping.
Seven contrasting cassava cultivars were grown in sole-cropping and in intercropping with soybean and with pigeonpea. In cassava/pigeonpea intercropping, time of pigeonpea sowing and plant density were altered in two experiments. In Experiment 1, four rows of pigeonpea were sown between cassava rows at cassava planting. In Experiment 2, two rows of pigeonpea or soybean were sown at 35 days after cassava planting.
In Experiment 1, cassava emerged later than pigeonpea.Canopy width of cassava did not increase once the cassava interrow was occupied by pigeonpea. Total dry-matter production of all cassava cultivars was severely affected in intercropping by the time of pigeonpea harvest.
Subsequent recovery was slow and final tuber yield in all cultivars was less than 25% of the corresponding yield in sole-crop.
When the competitive ability of pigeonpea was reduced in Experiment 2, only a short cassava cultivar was affected severely by pigeonpea, and its recovery was poor after pigeonpea harvest. Tall cultivars gradually became much taller than pigeonpea, and in most cultivars tuber yields were reduced by only up to 30%. The pigeonpea was almost completely suppressed by these cassava cultivars, and its seed yield was very poor.
It was concluded that the two species competed with each other for too long, and there was yield loss of cassava/pigeonpea intercropping over sole-cropping with any cassava cultivars, except one (MCol 1468) which was strongly competitive and produced a full cassava yield in intercropping.
This study has highlighted the need to develop intercropping systems that enhance productivity through the efficient sharing of resources (in this case, radiation). Excessive competition between component crops for the same resource can lead to unproductive systems.
1129 92 - 4/172
Australia, field trial, intercropping, cassava, genotypes, soybean, pigeonpea, selection criteria
CENPUKDEE, U. and S. FUKAI
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