Yield response of cowpea varieties to sowing dates in a Sudan savannah agroecology of Nigeria

In the Sudan savannah of Nigeria, sowing date of cowpea is an important production constraint due to erratic rainfall at the beginning and towards the end of the rainy season when temperatures are high. Field trials were conducted during the rainy seasons of 2009 and 2010 at Minjibir (lat 12o 08’N, long 08o 32’E, elevation 508 m above sea level) in Sudan savannah of Nigeria, to determine the appropriate date of sowing of some recently developed cowpea varieties. Split-plot design was used with three replications. Sowing dates (10 July, 17 July, 24 July and 31 July) were assigned to main-plots and cowpea varieties (IT98K-205, IT97K-499-35, IT98K-573-2-1, IT89KD-288 and IT99K-241-2) were assigned to sub-plots. The results showed significant differences among cowpea varieties for yield and yield components. Sowing date significantly affected the performance of the five-cowpea varieties. Interaction between sowing date and variety was not significant for grain yield, suggesting that the varieties responded similarly to sowing date. Cowpea sown on 31 July produced significantly higher number of pods, number of seeds and grain yield compared with other sowing dates. Increase in grain yield for a sowing date relative to 10 July sowing was 26, 77 and 106% for 17, 24 and 31 July sowing, respectively. The medium maturing variety IT98K-573-2-1 significantly produced the highest number of pods, number of seeds and grain yield at all sowing dates. Based on these findings, for obtaining optimum yield, cowpea varieties should be sown at the end of July while for maximum yield, medium maturing cowpea varieties such as IT98K-573-2-1 are recommended.Key words: Vigna unguiculata; grain yield; fodder yield; Sudan savanna

Physiological evaluations of maize hybrids under low nitrogen

Open Access JournalAbstract A field experiment was conducted during 2014 and 2016 rainy season at Tudun Wada, Kano and Shika, Zaria in the Northern Guinea Savanna of Nigeria in order to study the physiological responses of maize hybrids under low nitrogen. The experiment consisted of two nitrogen levels 0 and 120 N kg ha−1 as main plot and 8 drought-tolerant maize hybrids and 2 controls as subplot laid out in a randomized split plot design and replicated three times. Physiological parameters of hybrids were significantly affected by low nitrogen at both locations. Interaction between hybrids and nitrogen was significantly affected at both locations. Based on these results, application of nitrogen significantly increased the physiological growth indices of maize hybrids. The extent of increment in physiological reactions was additionally higher in Zaria in view of higher soil natural carbon and nitrogen and higher precipitation was better dispersed at this area. However recent hybrids were more tolerant to nitrogen stress and out-yielded the older hybrids. Therefore the recently released hybrids were more adapted to abiotic stresses

Assessing the use of a drought‑tolerant variety as adaptation strategy for maize production under climate change in the savannas of Nigeria

Open Access Journal; Published online: 26 Apr 2021The Decision Support System for Agricultural Technology Transfer (DSSAT) was used to quantify the impact of climate change on maize yield and the potential benefits of the use of drought-tolerant maize variety over non-drought tolerant variety in savanna ecological zones of Nigeria. Projections of maize yields were estimated for three locations representing different agro-climatic zones and soil conditions, in the mid-century (2040–2069) and end-century (2070–2099) under representative concentration pathways scenarios (RCP 4.5 and 8.5) against the baseline period (1980–2009). Relative to the baseline period, the ensemble Global Circulation Models (GCMs) predicted significant increase in minimum and maximum temperatures and seasonal rainfall across the sites. In the mid-century, ensemble GCMs predicted temperatures increase between 1.7–2.4 °C for RCP4.5 and 2.2–2.9 °C for RCP8.5. By end-century, the temperature increases between 2.2–3.0 °C under RCP4.5 and 3.9–5.0 °C under RCP8.5. Predicted seasonal rainfall increase between 1.2–7% for RCP4.5 and 0.03–10.6% for RCP8.5 in the mid-century. By end of century, rainfall is expected to increase between 2–6.7% for RCP4.5 and 3.3–20.1% for RCP8.5. The DSSAT model predictions indicated a negative impact on maize yield in all the selected sites, but the degree of the impact varies with variety and location. In the mid-century, the results showed that the yield of the non–drought tolerant maize variety, SAMMAZ-16 will decline by 13–19% under RCP4.5 and 19–28% under RCP8.5. The projection by end-century indicates a decline in yield by 18–26% under RCP4.5 and 38–47% under RCP8.5. The yield of the drought-tolerant variety is projected to decline by 9–18% for RCP4.5 and 14–25% for RCP8.5 in the mid-century and 13–23% under RCP4.5 and 32–43% under RCP8.5 by the end-century. The higher temperatures by both emission scenarios (RCP 4.5 and 8.5) were primarily shown to cause more yield losses for non-drought-tolerant variety than that of the drought-tolerant variety. There will be 1–6% less reduction in yield when drought-tolerant variety is used. However, the higher yield reductions in the range of − 13 to − 43% predicted for the drought-tolerant variety by the end of the century across the study areas highlighted the need to modify the maize breeding scheme to combine both tolerances to drought and heat stresses in the agro-ecological zones of northern Nigeria

Seed dressing maize with imazapyr to control Striga hermonthica in farmers’ fields in the savannas of Nigeria

Open Access Journal; Published online: 17 Mar 2020Use of small doses of imazapyr and pyrithiobac for seed coatings of imazapyr-resistant maize hybrids (IR-Maize) offers an effective means to control Striga hermonthica. Field trials were conducted in Bauchi and Kano States of Nigeria in 2014 and 2015 under heavy Striga infestation to evaluate the potential effectiveness of herbicide coated hybrids maize on Striga control in farmers’ field. Results showed that herbicide coated seeds reduced number of emerged Striga per m2 and Striga damage symptoms in farmers’ fields in all the locations. In Kano the number of emerged Striga was 4.9 to 7.9 times less in herbicide treated hybrids in comparison with those of the same hybrids planted without herbicide treatment. The Striga-resistant open pollinated variety (OPV) (TZL COMP1 SYN) had 6.7 to 8.0 times more Striga than the treated hybrids. In Bauchi, the number of emerged Striga on the untreated IR-maize hybrids were over four-times higher on the treated IR-maize hybrids than on the untreated hybrids. The Striga-resistant OPV check had four-times more Striga than the treated IR-maize hybrids and twice more than the untreated IR-maize hybrids across the two years. However, the effects of herbicide seed coating on grain yields were not consistent because of strong seasonal effects. The result revealed that coating of imazapyr-resistant hybrid maize seeds with imazapyr was effective in reducing Striga infestation in farmers’ fields. Although herbicide seed coating did not give consistent yield advantages of the hybrids over the untreated checks, a combination of herbicide seed treatment and genetic resistance to Striga would serve as an effective integrated approach that could significantly reduce the parasite seed bank from the soil and prevent production of new seeds. The IR-hybrids and the OPV checks contained Striga resistance/tolerant genes that protected them against drastic yield loss in the Striga infested fields in both Bauchi and Kano

Maize-soybean intercropping for sustainable intensification of cereal-legume cropping systems in northern Nigeria

Article purchased; Published online: 20 Nov 2017Field studies were conducted during the 2014 and 2015 wet seasons at Zaria in the northern Guinea savanna and at Iburu in the southern Guinea savanna of Nigeria to determine the productivity of maize– soybean intercropping system. There were four treatment combinations in the experiment: sole maize; sole soybean; maize spaced at 50 cm and intercropped with soybean; and maize spaced at 65 cm and intercropped with soybean. The experiment was laid out in a randomized complete block design with three replications. The results showed that sole cropped maize and soybean generally outperformed the intercropped component crops. Land Equivalent Ratio (LER) was greater than 1 for all the intercrop treatments, indicating that it is advantageous to grow maize and soybean in association than in pure stands. Except for 2014 in Zaria, LER for intercropped maize spaced at 50 cm was higher than that for maize spaced at 65 cm. Gross Monetary Value (GMV) was generally higher for intercrops than sole crops except in Iburu in 2015 where GMV for intercropped maize spaced at 65 cm was similar to those of sole maize and soybean. Monetary Advantage Index (MAI) was positive for all intercrop treatments in both locations and years, which shows definite yield and economic advantages compared to the sole cropping systems. This suggests that farmers can intercrop soybean and maize with maize spaced at 50 cm and 65 cm

Mitigating Striga hermonthica parasitism and damage in maize using soybean rotation, nitrogen application, and Striga-resistant varieties in the Nigerian savannas

Open Access article; Published online: 14 Aug 2020Striga hermonthica infestation causes significant losses of maize yield in the Nigerian savannas and several technologies have been developed and promoted to control Striga in maize. However, since no single technology has been found to be effective against Striga, integrated management is needed to achieve satisfactory and sustainable Striga control. Both on-station and on-farm trials were undertaken from 2013 to 2015 in Bauchi and Kano States of Nigeria to evaluate the performance of integrated Striga control technologies. In the on-station trials, a soybean–maize rotation did not suppress Striga in maize in either location. However, nitrogen application suppressed and reduced Striga infection, except in Bauchi in 2014. The soybean–maize rotation accompanied by N application reduced Striga damage in both locations. On farmers’ fields, rotating soybean with maize significantly reduced Striga infection. At the same time, the use of maize varieties with a combined tolerance to drought and resistance to Striga parasitism also increased maize grain yield on farmers’ fields, probably due to three factors: a reduction in Striga infection, reduced effects of a mid-season moisture deficit, and increased uptake of nutrients from the soil. We concluded that the use of Striga-resistant maize varieties in combination with the application of N fertilizer and rotation with soybean could increase the productivity of maize in Striga-infested fields in the Nigerian savannas

Yield, N uptake and N utilization of early maturing, drought and striga-tolerant maize varieties under low N conditions

Performance under sub-optimal nitrogen (N) conditions, of early maturing maize cultivars bred for tolerance to drought and Striga parasitism in the Nigerian savanna is not known. This study evaluated the tolerance of selected early maturing drought and Striga-tolerant maize cultivars to low N conditions in Northern Nigeria. The cultivars were evaluated at 30 and 100 kg N ha−1. The varieties were compared with an improved maize cultivar that is not tolerant to drought and Striga. Maize grain yield was 26% higher at 100 kg N ha−1 than at 30 kg N ha−1 in 2010 and 161% higher100 kg Nha−1 than at 30 kg Nha−1 in 2011. The drought and Striga-tolerant varieties produced consistently higher yields than the non-drought-tolerant variety particularly at 30 kg Nha−1. These cultivars also accumulated higher amount of N, had higher N-uptake efficiency or N-utilization efficiency than the non-drought-tolerant variety ACR 95 TZE-COMP4 C3. Grains yield at low nitrogen rate was associated with high ears m−2, high dry matter accumulation, high grains m−2, suggesting that these traits are linked to low-N tolerance. The good performance of the drought-tolerant maize varieties under low N suggests that varieties developed for drought tolerance may be tolerant to low-N conditions

Agronomic Response of Soybean Varieties to Plant Population in the Guinea Savannas of Nigeria

populations were the main plots, whereas varieties were subplots. The proportion of intercepted photosynthetically active radiation (IPAR) and leaf area index (LAI) increased with increasing plant population at both locations, indicating that high leaf area indices and high degree of canopy closure at higher plant population intercepted more light than the canopy at lower population and subsequently resulted in relatively high grain and fodder yields. At both locations, optimum plant populations ranged from 533,300 to 666,700 plants ha-1 across the years. The northern Guinea savanna location (Samaru Zaria) produced more pods m-2, grain yield, and fodder at higher plant populations than that at the southern Guinea savanna (Samaru-Kataf ). Varieties TGx1448-2E and TGx1904-6F intercepted higher proportion of IPAR had higher LAI and produced a greater number of pods m-2, seeds m-2, grain yield, and fodder than TGx1835-10E at both locations in years of good rainfall. These data suggest that soybean yields in the Guinea savanna of northern Nigeria can be increased using higher plant populations than those currently recommended

Assessment of the impact of crop management strategies on the yield of early-maturing maize varieties in the drylands of Niger Republic: Application of the DSSAT-CERES-Maize model

Maize is increasingly becoming important in Niger for use as food and feed. Production is however, faced with several abiotic and biotic constraints. Researchers have developed early-maturing maize varieties that are tolerant to drought, the parasitic weed Striga hermonthica and diseases that fit into the short growing production environment. The evaluation and deployment of these varieties would, however, involve costly and time-consuming field trials across the maize production zones of the country. The CERES-Maize model was applied to assess the performance of two early-maturing maize varieties under varying planting windows and nitrogen application in three agroecological zones of the country. The model was calibrated with datasets collected from field trials conducted under optimal conditions (supplementary irrigation and full nutrient supply) at three locations in northern Nigeria. The model was validated with independent data set obtained from field trials conducted in 2020 and 2021 at 4 locations in the Republic of Niger under rainfed conditions. For each variety the treatments were five nitrogen (N) rates (0, 30, 60, 90 and 120 kg ha−1). The results from model calibration and validation revealed that the model accurately reproduced the observed value for days to flowering, physiological maturity, aboveground dry biomass and grain yield with low nRMSE (0.4–12.7%) and high d-index (0.70–0.99) for both varieties. The long-term simulation results (1985–2020) showed that the maize performance was dependent on location, planting window and nitrogen rates. The variety 2014 TZE-Y yielded higher than Brico in all locations for all treatments because it takes longer to mature and accumulate higher dry matter and have higher number of kernels. Simulated yields were generally higher in the Sudan savanna agroecological zone than in the other zones because of higher rainfall and higher clay content of the soil in this zone. The response to N application was influenced by planting window in each agroecological zone. With the exception of two sites, grain yield declined with planting beyond July 14 (PW3) and response to N was not significant beyond this date in the Sudan savanna agroecological zone. Grain yield declined with planting beyond July 7 in the Sahel and Sudan Sahel agroecological zones. There was no further response to N beyond 30 and 60 kg N ha−1 when planting is delayed beyond July 7 in the Sahel and Sahel-Sudan agroecological zones, respectively