J. M. Bokosi

Phenotypic variation in fruit, seed and seedling traits of nine Uapaca kirkiana provenances found in Malawi

Uapaca kirkiana is one of the priority indigenous fruit tree species for domestication in southern Africa. Natural populations of U. kirkiana are declining due to deforestation, forest fragmentation and wildfires. Knowledge of genetic variation is prerequisite for development of conservation strategies. A provenance evaluation study was conducted at Bunda College of Agriculture in Lilongwe, central Malawi to determine the variability in fruit, seed and seedling characteristics of nine populations found in the southern, central and northern regions of Malawi. Results showed significant differences (P≤0.05) between provenances in fruit weight, seed weight, seed length and seed width. The central Malawi provenances of Dzalanyama and Chimaliro had the heaviest mean weight of fruits of 23.9g and 23.8 g respectively, the lightest fruits (14.6g) were found in Namoni Katengeza provenance. There were no significant differences (P≤0.05) in number of seeds per fruit within and between provenances. The provenances differed significantly in cumulative germination percentage, ranging from 26% for Tsamba provenance in southern Malawi to 87% for Dzalanyama provenance in central Malawi. There was a consistent regional variation in stem collar diameter and height growth with central Malawi (Dzalanyama and Chimaliro) and northern Malawi provenances having taller seedlings ranging from 5.2 to 9.0 cm, with the exception of Namoni Katengeza provenance in central Malawi. The root collar diameters were significantly higher for Dzalanyama and Chimaliro (2.5 to 3.9 cm) than southern Malawi provenances whose seedling collar diameter averaged 2.3 centimetres. The nursery provenance trial has shown existence of considerable variation in seed germination, fruit and seed traits in U. kirkiana. Seed and seedling growth traits may prove to be important criteria for selection of provenances for domestication to provide farmers with sustained fruit production for consumption and economic benefits.

Release of cowpea line IT99K-494-6 for yield and resistance to the parasitic weed, Alectra vogelii Benth. in Malawi

Field trials were conducted between 2008/09 and 2009/10 seasons to evaluate four new cowpea lines, selected in preliminary studies, for yield, adaptation and resistance to the parasitic weed Alectra vogelii in Malawi. The design was randomised complete block design with 4 replicates at research stations and 5 at on-farm sites. For on-farm, villages were the sites and each farmer hosted one replicate. The trial sites were Lisasadzi, Mngwangwa, Bunda College, Chitedze Research Station, Rivirivi and Mpokwa in 2008/09 season and in 2009/10 the sites at Chitedze and Mpokwa were replaced by Mkwinda and Chitala Research Station. Four promising cowpea lines, IT98K-503-1, IT97K-825-15, IT99K-7-21-2-2-1 and IT99K-494-6, all originally from IITA and selected for resistance to parasitic weed Alectra vogelii in screen house studies, were compared with released varieties Sudan 1, IT82E-16 and a farmers local entry. The following parameters were evaluated: cowpea grain yield, plants/m2, seeds/pod, seed weight (g/100 seeds), days to mid-flower, days to maturity, disease scores (scale 1 [clean] – 9 [most severe]) and A. vogelii emergence (plants/m2). The line IT99K-494-6 was found to have comparable or better agronomic traits as compared to control varieties and was eventually released in Malawi in January 2011. The line which is medium maturing has brown grain texture with yield potential of 1-2.0 t/ha. Such a resistant variety is important in A. vogelii hot spots to reduce build up in soil seed bank and a viable option for farmers to rotate with cowpeas in order to manage other pests such as Striga asiatica, an important parasitic weed, or improve soil fertility through the nitrogen fixation of cowpeas. Key words: Legumes, witchweeds, parasitic weeds, cowpea, Alectra vogelii, Vigna unguiculata.