The aim of the work was to study the genetic origin of the persistence of male bracts and neutral flowers in diploid bananas bred by crossing diploids and tetraploids. The genetic system proposed for somaclonal variation and evolution in triploid bananas is described. [L'objectif du travail a consisté à étudier l'origine génétique de la persistance des bractées mâles et des fleurs neutres chez les diploïdes dérivés de bananiers à partir du croisements entre diploïdes et tétraploïdes. Le système ...

Surveys of the incidence of African cassava mosaic disease (ACMD) and its whitefly vector, Bernisiu tabaci, were made at three-month intervals in 1992 and 1993 along two South-North transects. One was in central and the other in eastern Uganda. ACMD incidence was high within the northern localities of each transect and low towards the south. Incidence increased over the period at localities on the ACMD epidemic 'front' which was the interface between high incidence areas to the north and low ...

A field trial was established at Sendusu. 40 km north of Kampala. Uganda, to evaluate the response of yarn lines, developed by the International Institute of Tropical Agriculture (IITA), to nematode infestation. The field was naturally infested with nematodes and plants were established from tissue culture. Harvested yam tubers were infested mainly with Meloidogyne javanica and, to a lesser extent, with Pralylenchus spp.; Scutonel/onema sp., Rolylenchulus sp. and HelicOlylenchus sp. were round ...

Genetic enhancement of Musa spp. has aimed at producing hybrids with high yield, short stature, fast crop cycling, and disease resistance through interspecific and interploidy crosses. Progeny testing for parental selection has seldom been carried out in Musa and little is known on combining ability and heterosis in this species. A 5 _ 5 factorial mating design was used to estimate components of phenotypic variance in 4x-2x hybrid populations and to determine the combining ability of their progenitors ...

The long‐term effects of land clearing methods (manual, shear blade, tree‐pusher/root‐rake combination, traditional), tillage systems (disc ploughing, mechanized no‐tillage, traditional) and cropping systems (annual cropping, alley cropping, graxed pasture) on surface soil physical and chemical properties were evaluated on an Alfisol in south‐western Nigeria ten years after land clearing. Long‐term soil physical degradation was greatest after mechanized land clearing or tillage systems. The erosion ...

The herbicide imazaquin was tested for efficacy in striga gesnerioides and Alectra vogelii control when applied as a cowpea (Vigna unguiculata) seed treatment. Four sets of experiments were conducted in the laboratory and screenhouse. Two cowpea cultivar, three geographical isolates of S. gesnerioides from two hosts, and two geographical isolates of A. vogeli from two hosts were used. Preliminary experiments indicated cowpea seed treatments of 5-min duration in aqueous solutions of the ammonium ...

Changes in earthworm activity, water runoff, soil erosion, soil physical properties and fertility, and crop growth and yield caused by intercropping either maize (Zea mays L.) and cassava (Manihot esculenta Crantz) (MC) or maize, cassava and 'egusi' melon (Citrullus lanatus Thunb.) (MCM) on no-tilled and handhoe-tilled plots were studied in an Alfisol in southwestern Nigeria. Runoff and erosion in no-tilled plots were negligible and were not affected by cropping system. Similarly, soil compaction ...

The aleyrodid Aleurodicus dispersus is reported from Nigeria. The first observation was made on cassava in early 1992 at several locations in Ibadan. A survey carried out in January 1993 revealed that several genera, many of them important food and ornamental crops, are food plants of the insect.

The environment substantially affects the performance of tomato (Lycopersicon esculentum Mill.) genotypes in Latin America and the Caribbean (LAC). Therefore, stability analysis can be used to select stable, high-yielding genotypes. Nine open-pollinated and six hybrid tomato genotypes and the most representative local tomato cultivar were evaluated at 20 LAC locations. Each cultivar's yield stability was quantified using the regression of individual genotype's yield on the environmental index, ...