Idorenyin Asukwo Udo

Salinity episodes that are common in arid regions, characterized by dryland, are adversely affecting crop production worldwide. This study evaluated the effectiveness of brassinolide (BL) in ameliorating salinity stress imposed on soybean at four levels (control (1.10), 32.40, 60.60 and 86.30 mM/L NaCl) in factorial combination with six BL application frequency (control (BL₀), application at seedling (BL₁), flowering (BL₂), podding (BL₃), seedling + flowering (BL₄) and seedling + flowering + podding (BL₅)) stages. Plant growth attributes, seed yield, and N, P, K, Ca and Mg partitioning to leaves, stems and roots, as well as protein and seed-N concentrations, were significantly (p ≤ 0.05) reduced by salinity stress. These trends were ascribed to considerable impairments in the photosynthetic pigments, photosynthetically active radiation, leaf stomatal conductance and relative water content in the leaves of seedlings under stress. The activity of peroxidase and superoxidase significantly (p ≤ 0.05) increased with salinity. Foliar spray with BL significantly (p ≤ 0.05) improved the photosynthetic attributes, as well as nutrient partitioning, under stress, and alleviated ion toxicity by maintaining a favourable K⁺/Na⁺ ratio and decreasing oxidative damage. Foliar spray with brassinolide could sustain soybean growth and seed yield at salt concentrations up to 60.60 mM/L NaCl.

Field experiments were conducted in 2012 and 2013 at the Teaching and Research Farm of the University of Calabar, Cross River State, Nigeria to determine the effectiveness of integration of Fitsextra® (a solution containing Atrazine and Metolachlor herbicides as active ingredients), egusi melon and hand-weeding on weed management and tuber yield of cassava. The twelve treatments which involved individual and combinations of the above mentioned weed control methods were laid out in a randomized complete block design and replicated three times. Irrespective of the method adopted, weeding depressed weed density by 57.33 % and 63.99 % in 2012 and 2013, respectively and weed biomass by 81.00 % and 79.64 % within the same period compared with the unweeded check. Integration of Fitsextra with egusi melon and/or hand-weeding significantly (P<0.05) suppressed weeds more than the sole use of Fitsextra® or egusi melon. Integration of hand-weeding with Fitsextra and/or egusi melon reduced weed dry matter by 43.46, 87.25, 92.34 and 93.51 % in 2012, and by 53.20, 90.20, 94.61 and 94.56 % in 2013 compared with hand-weeding alone, Fitsextra alone, egusi melon alone and no weeding, respectively. Plots that were hand-weeded thrice and those treated with Fitsextra + hand-weeding twice significantly (P<0.05) produced the highest fresh tuber yield of 9.73 and 10.23 t/ha, respectively in 2013. No weeding reduced cassava tuber yield by 4.83 t/ha (84.89 %) on a 2-year average, compared with the weeded plots. Conclusively, the results indicated that, three hand-weeding optimized cassava tuber yield, however, the integration of Fitsextra or egusi melon can effectively replace the first hand-weeding.

Glasshouse experiments were conducted to evaluate the efficacy of application frequency of a bioformulated Paecilomyces lilacinus in combination with five concentration of Lantana camara crude aqueous leaf extract against Meloidogyne incognita race I on tomato. The experiment was a 3x5 factorial laid out in a completely randomized design (CRD) with four replications. Each seedling was inoculated with 5000 eggs of M. incognita. Application of the bionematicide and L. camara leaf extract alone significantly (P≤ 0.05) inhibited root galling and egg production compared with their respective control. However, the severity of root galling and egg mass production was more significantly (P< 0.05) suppressed with the application of P. lilacinus than L. camara leaf extract. Double inoculation with P. lilacinus in combination with 0.80 g mL^-1 of the L. camara leaf extract changed the susceptibility of the tomato cultivar with gall index (GI=4.00) to GI=1.50. Application of P. lilacinus twice (at transplanting and two weeks after transplanting) in combination with 0.80g mL^-1 of L. camara leaf extract was the most effective treatment in gall and egg mass inhibition, growth enhancement and dry matter accumulation. This environment-friendly approach could be incorporated into integrated root-knot disease management in tomato.