Selection of High Yielding and Farmers’ Preferred Genotypes of Bambara Nut (<i>Vigna subterranea</i>(L.) Verdc) in Malawi

Bambara nut (Vigna subterranea (L.) Verdc) is a nutritious legume, however, its production is characterised by use of landraces, which have been maintained by farmers. Lack of improved varieties has contributed to low yields. This re- search was done to identify potentially high yielding and farmers’ preferred genotypes for improved production of Bambara in Malawi. A completely Randomised Block Design experiment with eight genotypes (181CR, 181RD, 194, 137CR, 137RD, 317, 2762 and 2768) and four replicates was implemented at Chitedze, Chitala and Mbawa Research Sta- tions to identify high yielding genotypes. In addition to the yield, farmers’ criteria based on plant vigour, ability to fully bury its pods in the ground (mounding), yield at harvest, maturity period, seed colour, grain size, taste of boiled dry grain and taste of fresh pods were used to identify farmers’ preferred genotypes. Significant yield differences were identified between genotypes (P < 0.0001), sites (P < 0.001) and interaction between genotypes and sites (environment) (P < 0.001). Yield means across sites show that genotype 181CR yielded highly (1322 kg/ha) followed by 2768 (1066 kg/ha), 181RD (1064 kg/ha) and 2762 (841 kg/ha). In contrast to the high yielding genotypes, genotype 137RD gave the lowest yield (485 kg/ha) followed by 194 (573 kg/ha), 317 (617 kg/ha) and 137CR (620 kg/ha). Mbawa Research Sta- tion showed significantly high yields with site mean of 1177 kg/ha compared with Chitedze and Chitala with site means of 703 kg/ha and 530 kg/ha respectively. Farmers ranked the eight accessions in order of importance as follows: 181RD, 181CR, 2768, 137CR, 194, 137RD, 2762 and 317. Combination of yield and farmers’ preference identified three geno- types (181RD, 181CR and 2768) as potential varieties for production in Malawi. Accessions 181RD and 2768 were specifically selected for relish unlike 181CR, which has been selected for use as snack. However, further research on nutrition, value addition and marketing needs to be conducted on the identified genotypes.

Impacts of Small-Scale Water Management Interventions on Crop Yield, Water Use and Productivity in Two Agro-Ecologies of Malawi

A study was conducted in Malawi to compare the performance of improved agricultural water ma- nagement interventions with traditional water management practices to assess the impact of the interventions on crop yield and water use productivity. The study used questionnaires and focused group discussions to collect data from farmers and key informants. The results showed significant gains in crop yield, farmer income, and water use productivity using the regulated surface irrigation compared with unregulated surface irrigation. Treadle pump irrigation increased crop production by 5% - 54% compared with water can irrigation. Treadle pumps also increased gross and net incomes by >12% suggesting that farmers using the treadle pump were able to realize higher incomes across all crop enterprises compared with farmers using water cans. However, there is a dire need to improve the efficiency of the surface irrigation systems for rice production because the water applied was about 2 to 3 times the gross irrigation requirement (~10,780 m3·ha-1) which could result in environmental degradation through increased salinity and water logging.

Photosynthetic Water Use Efficiency of Heritage and Modern Potatoes under Limited and Unlimited Water Environments

Photosynthetic capacity for heritage (Taewa) and modern potato cultivars were compared at different water and nitrogenregimes in the glasshouse and field. The glasshouse was 2*2*4 factorial design with two irrigation: 100% ET and 60% ET;two applied N: 50 kg N ha-1 and 200 kg N ha-1, two Taewa (Moe Moe, Tutaekuri) and two modern potatoes (Moonlight, Agria). The 2009/2010 field experiment was a split-plot, with irrigation and rain-fed regimes as the main treatments: four potatoes above were sub-treatments. The 2010/2011 field experiment was a split-split-plot, with three water regimes as the main treatments: three cultivars (Moe Moe, Tutaekuri, and Agria) were subplots;two N rates were sub-sub-treatments. Gaseous exchange was measured by CIRAS-2 at different days from emergence. Leaf water potential was measured using pressure chamber method. Taewa achieved high photosynthetic WUE in glasshouse and 2010/2011 experiment by maintaining high An, low gs and low Ci compared to modern cultivars (p The An, gs and T increased with irrigation and N increase while decreasing Ci (p < 0.01). Water stress significantly increased VPD resulting in low An and photosynthetic WUE in Moonlight in the glasshouse. The leaf water potential for Taewa was very tolerant while modern potatoes were weakened by water stress. The study indicated that Taewa can be scheduled at partial irrigation without more detrimental effects on photosynthetic capacity while modern potatoes need full irrigation to avoid detrimental effects on photosynthetic capacity.