Bonny R. Ntare

Intercropping morphologically different cowpeas with pearl millet in a short season environment in the Sahel

The effects on yield of varying the planting date and planting pattern of morphologically different cowpea cultivars intercropped with pearl millet were studied in two field trials. The interaction between cowpea cultivars and planting date was highly significant. There was a sharp reduction in cowpea yields with late planting. Millet yields were reduced less when sown simultaneously with early cowpea cultivars than when sown with a late maturing local cultivar. Early maturing cowpea cultivars planted in closely spaced hills had less effect on millet yields than a late maturing cultivar sown in widely spaced hills. An appropriate cowpea cultivar for intercropping with peal millet would be one that was weakly competitive and that yielded both grain and fodder

Utilizing Conjoint Analysis to Design Modern Crop Varieties: Empirical Example for Groundnut in Niger

Preferences for monetary and non-monetary plant traits influence modem crop variety adoption decisions of farmers. To enhance adoption probability of modem crop varieties, it is necessary to identify and focus research on traits that significantly contribute to utility while de-emphasizing insignificant plant attributes. This paper illustrates the potential for applying conjoint analysis to aid the design and targeting of client-responsive modem crop varieties. Farmers ranked eight orthogonally-derived plant trait combinations used in an illustrative example. Utilities were estimated using the choice-probability-based method of ordered probit. Results showed that conjoint analysis can differentiate significant and non-significant traits of modem crop varieties. The usefulness of applying conjoint analysis over identifiable disaggregated groups of a sample was also evident. Future application of conjoint analysis to the design and targeting of modem crop varieties should carefully consider sample composition and size to permit the estimation of relevant sub-models for desired farmer segments.

Evaluation of cowpea cultivars for intercropping with pearl millet in the Sahelian zone of West Africa

Abstract Field trials were conducted at ICRISAT Sahelian Centre, Niger, to examine the performance of contrasting cowpea cultivars intercropped with pearl millet. Significant effects ( P ≤ 0.05) of cropping system and cultivars were observed for cowpea grain yield. Cultivar × cropping system interaction was significant only for fodder yield. Intercropping reduced cowpea yields significantly but the degree of reduction varied among cultivars. Early-maturing erect cultivars exhibited greater yield reduction than the indeterminate spreading types and had the least effect on millet yields. Indeterminate spreading cultivars produced greater grain and fodder yield than erect types and caused the greatest millet yield reduction. The relationship between the yield of cowpea cultivars and millet when intercropped was negative. Linear correlations between yield of cowpea in sole and intercrop were positive and significant ( P r values ranging from 0.45 to 0.91. However, a small proportion of the greatest and least-yielding cowpea cultivars in intercropping would have been selected and rejected, respectively, on the basis of sole-crop grain-yield. It was concluded that selection of cowpea cultivars for intercropping with millet based on their grain yield in sole crop may have limited success. Selection based on fodder yield favoured late-maturing cultivars. Selection of cowpea cultivars for intercropping should be based on their intercropped performance, paying special attention to other agronomic factors. An appropriate cowpea cultivar for intercropping with millet would be the one that is less competitive with millet and yields both grain and fodder.

Farmer preferences for socioeconomic and technical interventions in groundnut production system in Niger: Conjoint and ordered probit analyses

Crop production decisions reflect preferences of farmers which are based on the structure of incentives and constraints that characterize agricultural systems. Therefore, an assessment of the intensities of farmer preferences for technical and socioeconomic interventions can provide useful guidance for the choice of appropriate strategies to improve productivity and incomes. Based on surveys conducted in groundnut-growing zones of Niger in West Africa, utilities of selected socioeconomic and technical interventions to farmers were derived through application of conjoint and ordered probit analyses. Across all regional and gender subgroups of respondents, groundnut farmers attach significant importance to access to credit and reliable markets for pods. The introduction of new and more productive varieties per se would not significantly contribute to utilities of farmers at the present time. This possibly implies that until market and credit constraints are alleviated, farmers have lower utility for more productive varieties. Regional diversities were observed in the significance of utilities groundnut farmers can gain from the availability of local small-scale groundnut oil processing plant, fertilizer and changes to traditional rules governing access to land. There is no evidence of genderbased diversity in utilities and, therefore, prioritization of the interventions on the basis of observed utilities will benefit both gender components.

Response of cowpea cultivars to planting pattern and date of sowing in intercrops with pearl millet in Niger

A two-year study was conducted at two locations in Niger to compare the response of five cowpea cultivars to two planting patterns and two sowing dates relative to the sowing date of pearl millet. All the cowpea cultivars took less time to mature when planted three weeks after millet than when sown one week after. Early-maturing cowpea cultivars had the smallest yield, whereas the yield of the local indeterminate cultivar was nearly double that of the other cultivars at both dates of sowing. Early planting of cowpea significantly depressed millet yield, but when cowpea was planted late millet yields approached those of the sole crop. The local cultivar depressed millet yields more than the other cowpea cultivars. Planting pattern had no significant effect on the yield of either cowpea or millet. Cowpea yield was reduced by more than 50% by two weeks delay in sowing, confirming that the sowing date of cowpea relative to millet is a critical factor in the Sahelian pearl millet/cowpea intercropping system. There were marked differences in the effect of cowpea cultivar on millet yield but these differences were consistent over sowing dates.

Heritability of components of a simple physiological model for yield in groundnut under semiarid rainfed conditions

Use of physiological models has been suggested as a means to improve efficiency of breeding for higher yield. Our objectives were to estimate heritabilities of yield components of groundnut (Arachis hypogaea L.) identified in a yield model [crop growth rate (C), reproductive duration (DR) and partitioning (p)] and determine their predictive value in early generations. Forty bulk populations and nine parental lines were evaluated in replicated trials in 1992 (F2), 1993 (F3) and 1994 (F4) at three contrasting locations in Niger. Physiological components of yield were estimated from final yield and biomass as well as data on ¯owering and maturity. Differences were observed among populations for pod yield and model components. The effects of locations were signi®cant (P<0.01) for C, p and DR in F2 and F3 but nonsigni®cant for yield and C in F4. Heritabilities were estimated by parent±offspring regression of F3 on F2 and F4 on F3. Heritability estimates for C, p, DR and yield based on the F2:F3 regression were 0.10, 0.45, 0.10 and 0.16, respectively. Heritabilities based on F3:F4 regression were 0.20 for C, 0.46 for p, 0.14 for DR and 0.57 for yield. These results reveal that none of the yield-model traits had larger heritability than yield and that selection for these traits in segregating bulk populations is difficult.

Physiological determinants of cowpea seed yield as affected by phosphorus fertilizer and sowing dates in intercrop with millet

Abstract The interaction of cowpea (Vigna unguiculata (L.) Walp.) cultivars with management factors and environments was analyzed in terms of parameters of a simple physiological model. In one set of experiments seven cultivars were sown at three rates of phosphorus (P) fertilizer (0, 8 and 16 kg P ha−1). In another set, five cultivars were sown on two dates relative to sowing of millet (Pennisetum glaucum (L.) R.Br.). All experiments involved factorial combinations of management and cultivar treatments, and were conducted in 1988 and 1989 at two sites in western Niger. Seed yield, shoot dry matter, vegetative (Dv) and reproductive (Dr) durations were determined and crop growth rate (C) and partitioning (p) to seed estimated. Application of P increased seed yield by increasing C. As sowing was delayed from 1 to 3 weeks after the millet was sown, there was a reduction in seed yield due to decreases in C, Dv and Dr. Variation in cultivar performance across years was mainly a function of C and partitioning. In both experiments the C of the landrace Sadore Local was greater than that of other cultivars, although the partitioning to seed of this cultivar was unstable due to variable control of insect pest damage. It is concluded that the primary causes of G × E interactions were differential canopy development and insect damage effects. Therefore in the development of cowpea cultivars for intercropping with millet, emphasis should focus on light capture capabilities. Improved yields would then seem possible with most cultivars, providing insect damage is controlled.

Selection of cowpea cultivars for cool-season production in the Sahel

Cowpea (Vigna unguiculata (L.) Walp.) is traditionally grown during the short rainy season in the Sahelian zone of west Africa, but there are opportunities for dry-season production providing the problems of low night temperatures can be overcome. The objective of this research was to identify cultivars suitable for irrigated cropping during the cool post-rainy season. Four hundred and thirtytwo lines representing breeding and local germplasm lines from Niger were tested for field emergence, flowering and podding in the coolest time of the year. A selected set of lines was evaluated for yield and other characteristics. Seedling emergence began 8 days after sowing and seedlings emerged over a 7-day period. Seventy-four percent of the local germplasm lines recorded 76–100% emergence as compared to 4% of the breeding lines. The growth of seedlings was very slow. The time to maturity was not well related to the maturity during the normal cropping season. Cooler temperatures prolonged time to maturity. All lines flowered but some did not set pods. The highest pod set was recorded in the early-maturity group. Grain yield and related attributes declined sharply when sowing was done in January as compared with the November sowing. The differences observed among selected cultivars and sowing dates were mainly due to variation in crop growth rate.

SSR markers associated to early leaf spot disease resistance through selective genotyping and single marker analysis in groundnut (Arachis hypogaea L.)

Highlights • Marker trait association for ELS in groundnut.• Single marker analysis (SMA) and selective genotyping approaches identified markers associated with ELS resistance.• Four markers were found common between the two trait mapping methods.