Albizia lebbeck is a multipurpose tree species prioritised for conservation in Malawi. The different plant parts are used in traditional medicine to treat different diseases. However, the seeds are dormant, and the tree species remain undomesticated. A study was conducted to evaluate the effect of seed size and presowing on the germination of Albizia lebbeck in a nursery. Seeds were grouped into four categories in regard to their length, small (≤0.5 cm), medium ( cm), large (≥0.8 cm), and mixture of small, medium, and large seeds. The seeds were subjected to five main seed pretreatment methods, namely, soaking in sulphuric acid for 2 minutes, nicking, soaking in hot water for 5 minutes, soaking in cold water for 24 hours, and control where seeds were sown without any treatment. The results indicate that combination of nicking and large seeds produced the highest (100%) germination. Hot water treatment was effective in large seeds producing 67.5% germination. The increased germination for mechanically scarified seeds through nicking suggests that seed dormancy in Albizia lebbeck is mainly due to its hard seed coat. Therefore, it is recommended to farmers to adopt use of nicking and large seeds, since it is safe and effective.

SUMMARYA study was conducted to evaluate performance of two rice (Oryza sativa L.) varieties under water saving irrigation through alternate wetting and drying in sandy clay loams of Southern Malawi. The varieties, Nunkile and NERICA 4, are adapted to upland and lowland irrigated conditions, individually, and commonly grown by farmers. Four irrigation regimes were used in the study: (1) continuous flooding with surface water level kept at approximately 5 cm throughout crop duration (CFI), (2) alternate wetting and drying up to start of flowering after which continuous flooding was applied (AWD1), (3) alternate wetting and drying up to start of grain filling after which continuous flooding was applied (AWD2) and (4) alternate wetting and drying throughout the crop duration (AWD3). While seasonal crop water requirement was 690 mm, total irrigation depths were 1923.61, 1307.81, 1160.61 and 807.87 mm for the four regimes respectively. The CFI treatment used 32%, 40% and 58% more water than AWD1, AWD2, and AWD3 regimes respectively. In the same treatment order, the average yields per treatment for Nunkile were 4.92, 4.75, 4.74, and 4.47 t ha−1 with significant yield differences among CFI, AWD2 and AWD3 treatments. The average yields per treatment for NERICA 4 were 3.93, 3.75, 3.75, and 3.71 t ha−1 with significant yield differences only between CFI and all AWD treatments. Crop water productivity (CWP) was higher for Nunkile compared with NERICA 4 across all irrigation treatments, while CWP for CFI treatment was superior to all three AWD treatments grown under either variety. Thus, CWP was not increased with AWD irrigations. AWD till flowering and grain filling did not significantly differ with respect to yield and CWP. It is suggested that for similar conditions and where water is scarce, rice can be grown by AWD till grain filling as it saved more water. An important part of the research is to extend the initial results beyond the climate and soils of study.

Manual weeding, maize-cowpea intercropping, pre-emergence (PRE) and early post-emergence (EPOST) herbicide applications comprised ten weed control practices evaluated in the 2015-16 cropping season on weed species structure and maize (Zea mays L.) yield in the Middleveld and Highveld of Swaziland. The herbicides used were Harness (acetochlor) and Dual Gold (S-metolachlor) as preemergence applications and Micro-Tech (alachlor) and Callisto (mesotrione) as early post-emergence applications. PRE and EPOST herbicides were used as once-off or combined applications besides manual weeding or intercropping practices. Results indicated that the combination of PRE and EPOST herbicides reduced both species richness (number) and evenness (dominance) but weed species composition (types) were not distinguished amongst treatments. Manual weeding in combination with PRE herbicides or maize-cowpea intercropping resulted in significantly lower weed density and biomass as compared to singular or combinations of PRE or EPOST herbicides in both locations. The effects of weed control practices on grain yield of maize were not significantly distinguished among weed control practices between the two sites. The study reaffirmed that herbicides may need to be supplemented with other weed control strategies to obtain acceptable weed control.