Yield of plantain alley cropped with Leucaena leucocephala and Flemingia macrophylla in Kumasi, Ghana.

The decline in yield of plantain (Musa spp.) has partly been attributed to inadequate soil moisture and pests, particularly nematodes. The objectives of this study, therefore, were to determine the effect of mulch from Leucaena leucocephala and Flemingia macrophylla grown as hedgerows on (i) soil moisture and temperature, (ii) growth and yield of plantain, and (iii) pathogenic nematode populations. The study was conducted from 1991 to 1994 in Kumasi, Ghana. Treatments comprised L. leucocephala and F. macrophylla hedgerows (5 rows at 3X1 m spacing) established with 4-wk-old seedlings in May 1991, and a no-tree control. The trees were pruned for the first time 15 months after planting, and thereafter at 3-month intervals; the prunings were applied to the alleys as mulch. The plantain (false horn plantain cv. Apantu pa) was planted as suckers in July 1992, with 1 row per alley spaced at 2 m (5 plants); 3% carbofuran was applied at 2 g per planting hole for nematode and banana weevil (Cosmopolites sordidus) control. Weed control was initially with glyphosate and later by slashing, and NPK fertilizer was applied 1, 4, 6 and 16 months after planting. The highest biomass yield was produced by F. macrophylla. Mulching with prunings of F. macrophylla resulted in a significantly higher retention of soil moisture and lower soil temperatures than mulching with prunings of L. leucocephala. Growth of first-cycle plantain determined by plant height, leaf production, pseudostem girth and yield were significantly greater in F. macrophylla mulched plots than in L. leucocephala mulched plots and control plots where no mulch was applied. Plant parasitic nematodes isolated were Meloidogyne spp., Pratylenchus spp., Paratylenchus spp., Helicotylenchus spp. and Rotylenchus spp. Three years after planting the hedgerows, significantly higher populations of Meloidogyne spp. (367 per 100 g soil), Paratylenchus spp. (92 per 100 g soil), Helicotylenchus spp. (8 per 100 g soil), and Rotylenchus spp. (308 per 100 g soil) were associated with the L. leucocephala hedgerows than with Flemingia macrophylla hedgerows (42.0, 83.0 per 100 g soil) and the control (74.50, 41.0 per 100 g soil). F. macrophylla has qualities that suppress nematode populations. The results clearly indicated the superiority of Flemingia macrophylla over Leucaena leucocephala as mulch for plantain production.