Eucalyptus camaldulensis Dehnh is an exotic species found in Sahel agroecosystems, often growing alongside annual crops. However, there is limited documentation regarding its ecological impacts on these crops. This study aims to assess the influence of eucalyptus on crop physiological traits and yield. To accomplish this, on-farm experiments were conducted over two years (2022 and 2023), employing a tree effect gradient called a gradient-based design with 4–7 replications for cowpea, millet, and sorghum. The experimental design included three plot locations based on their proximity to the eucalyptus trunk: one directly under the crown, another centred at 11 m, and a control plot situated 22 m away. Various parameters, such as height, relative chlorophyll content, leaf area index, photosynthetically active radiation, and yields of grain straw, were measured across all plots and years. Results from pairwise tests indicated significant differences among the plots for most parameters studied. Notably, plant height significantly decreased in proximity to eucalyptus (p < 0.000) throughout the two years. For relative chlorophyll content, the millet and sorghum in 2022 presented significant differences between plots located at 22 m and plots under the crown (p = 0.000). The photosynthetically active radiation indicated significant differences between the plot located at 22 m and the plot under the crown in cowpea, sorghum (2022 and 2023). Additionally, grain and straw yields were significantly lower near the eucalyptus in both years (p < 0.05). These findings suggest potential ecological risks associated with growing certain crops close to eucalyptus in the Sahel context.
Tag: cowpeas
Weed population in cowpeas (Vigna Unguiculata) (L) Walp) as influenced by water table, moisture regime and cultivar
Experiments were conducted during the 1987-88 dry season to determine the influence of irrigation water and naturally occurring water table depths in a toposequence, on the weed ecology of two cowpea [Vigna unguiculata (L.) Walp] cultivars at Los Banos, Philippines. In the line source sprinkler irrigation experiment on a Typic Tropudalf, saturated and wet treatments had a higher weed population than the dry treatment. In the toposequential agrohydrology experiment, the shallow and medium water table depths had greater weed populations than the deep water table depth regime. In both experiments the early maturing cultivars had a higher LAI [leaf area index] in their early phase of growth. This was associated with reduced weed competition as compared to the medium maturing cultivars, irrespective of moisture regimes.
Cowpea water relations and growth on a toposequence water table gradient
Cowpea sown after wetland rice in tropical monsoon climates is frequently subjected to soil saturation and a high water table during early growth. We compared the effects of variation in water table regime on the shoot and root growth, and plant water relations of two medium-maturing (cv. TVX3236-01G and TVX3410-02J) and two early maturing (cv. BS6 and IT82D-889) cowpea [Vigna unquiculata (L.) Walp] cultivars in three water table depth regimes on a Typic Tropudalf toposequence. Our objective was to elucidate the possible mechanisms of differential cultivar adaptation to shallow water table conditions. The shallow water table regime (SWT) significantly reduced the total dry matter accumulation and harvest index for BS6, an early maturing cultivar (reductions in stems, leaves, pods, and total dry matter by 82, 77, 88, and 84% respectively), while the least reductions (reductions by 44, 3, 57 and 55%, respectively) was observed for TVX 3410-02J, a medium-maturing cultivar. Roots of the medium cultivars were more concentrated in the top 0.2m in the SWT Site than those of the early-maturing cultivars. Roots of the medium cultivars later penetrated to 0.8-m maximum depth compared to 0.6-m maximum depth for the early cultivars, and extracted soil water from 20 cm deeper in the soil profile than the early maturing cultivars. The medium-maturity cultivars maintained higher leaf water potentials and lower canopy temperatures throughout the season. This was associated with greater end-of-season total soil profile water extraction. The medium-maturing cultivars showed better adaptation to shallow water table conditions due to superior plant water status, rooting pattern, and biomass production and partitioning.
Cowpea production in rice-based cropping systems of the Philippines—Extrapolation by simulation
There is a growing interest in cultivating cowpeas (Vigna unguiculata (L.) Walp.) in the tropics to meet the protein requirements of small farmers, forage requirements of ruminants, and to attain more sustainable agricultural systems. A mechanistic crop growth model was used to estimate yields of partially irrigated and strictly rainfed crops of IT82D-889, an early maturing cowpea cultivar, and TVX1948-012F, a medium maturing cowpea cultivar. Average yield and yield stability of these cultivars were determined for fields with a shallow and a deep water table before and after the growth of rice (Oryza sativa) in various parts of the Philippines. Long-term simulation results indicated that the yield of TVX1948-012F varied from 100 to 2250 kg ha1, and that of IT82D-889 varied from 50 to 1600 kg ha1 for fields with a shallow water table and for partially irrigated conditions. Yields were greater for the post-rice than for the pre-rice season. Partial irrigation increased long-term biomass compared with those for strictly rainfed situations by 30% in the pre-rice season and by 104% in the post-rice season. Yields were more stable at Davao than at Los Baños or Iloilo. The two maturity classes of cowpea cultivars appear to have somewhat different extrapolation domains. The study demonstrates that mechanistic simulation modelling can be a useful tool to delineate the extrapolation domains of crops and cultivars.
Yield stability of cowpea cultivars in rice-based cropping systems: Experimentation and simulation
There is potential in cultivating cowpeas (Vigna unguiculata (L.) Walp.) in rice-based cropping systems in the humid tropics as a source of proteins for humans, forage for ruminants, and for improvement of soil fertility. Seasonal and yearly variability is, however, a major constraint. A statistical stability model and a mechanistic simulation model were used to quantify yield variability of early and medium maturity groups of cowpea cultivars in pre- and post-rice environments at Los Baños, Philippines.Four field experiments, with 24 cultivars in each experiment, were conducted in pre- and post-rice environments, to determine the response of the cultivars to varying moisture and to water table depth regimes, and a stability analysis was performed across the regimes using a statistical model. In the post-rice environment, irrespective of moisture and water table depth regimes, the medium maturing cultivars tended to outyield early maturing cultivars, whereas in the pre-rice environment, early maturity demonstrated a distinct yield advantage.The statistical stability model indicated that medium maturing cultivars performed well in high-yielding environments, whereas in low-yielding environments their yields were comparable with those of early maturing types. However, results of the statistical stability model are limited because of the short time series of basic data. To broaden the analysis, a simulation model of the cowpea crop was calibrated and validated for its performance. Measured and simulated dry weights of crop parts (leaves, stems and pods) and soil moisture contents at 10-cm soil depths throughout the growing season indicated satisfactory performance of the simulation model. Long-term simulation results using the validated model indicate that TVX1948-012F (medium maturity) performs betters (800–2250 kg ha1) than IT82D-889 (early maturity) (430–1620 kg ha1) with a fluctuating shallow water table in the post-rice environment, whereas IT82D-889 is superior (80–1150 kg ha1) to TV1948-012F (30–1150 kg ha1) in the pre-rice environment. Yields are highest and least variable for the 15 January planting in the post-rice environment, and for the 15 April planting in the pre-rice environment.