No abstract

No abstract

This article describes: (1) some of the effects of HIV/AIDS on rural communities in cast and southern Africa (2) the indications for the development of such impacts in Uganda, Tanzania and Zambia over the medium term, noting similarities and differences between the three countries; (3) explores the policy implications of these findings; (4) presents a generalised response strategy.

Genetic improvement of bananas is hampered by male and female sterility in most of the cultivated varieties. In addition, the triploid status of the edible varieties results in very low seed set during artificial hybridizations. The objective of this study was to determine the optimal periods in the year for seed set in East African Highland banana hybrids by examining seed set patterns in a number of varieties over different times of the year. In this article, we present the results of data collected in two different experiments that covered a period of six years. In the first experiment, fifteen female varieties were each crossed with a highly fertile male species, Musa acuminata ssp. burmannicoides 'Calcutta 4' from January 1995 till December 1997. In the second experiment nine female varieties (not exclusive of the first) were each crossed with male parents, ' TMB2x7197-2', 'TMB2x5105-1', and 'TMB2x8075-7' from January 1998 till December 2000. One of the interesting insights obtained from this study is that the number of seeds obtained from pollinations in East African Highland banana varied at different times of the year. In general, two major seed set periods were observed within a year with a major peak occurring in March-April and a minor peak occurring in September. Optimal seed set in the East African Highland banana appeared to be related to climatic variables.

The quantity and quality of pollen produced by a genotype are important attributes to be considered in the selection of male parents for breeding. The objective of this research was to determine the quantity and quality of pollen in 13 selected East African Highland bananas (EAHB) in relation to six diploids commonly used as male parents. Pollen quantity was scored on a scale of 0-6 while the variation of pollen stainability along the rachis was determined using acetocarmine glycerol jelly. Actual male fertility was determined by using pollen from the EAHB varieties on M. acuminata spp.burmannicoides, 'Calcutta 4', as the female. The diameter of 200 viable pollen grains was measured under a microscope with the aid of a graduated eyepiece. Significant differences were obtained for mean pollen stainability and pollen diameter. The pollen stainability for diploids was higher than that for the EAHB. Node numbers contributed significantly to variation of pollen stainability in EAHB (P B 0.01) and 'Pisang lilin' (P B 0.001). 'Pisang lilin' and the EAHB varieties had about 100 nodes as opposed to about 200 in other diploids. The EAHB varieties produced less pollen than most of the diploids. The actual male fertility of EAHB varieties was low (1 seed/bunch), compared to that of 'Calcutta 4' (223.3 seeds/bunch) and 'Pisang lilin' (13.7 seeds/ bunch). Although the production of 2n pollen in EAHB varieties was low (0-7%), the potential exists for using them in new breeding approaches.

No abstract