Cassava-maize intercropping systems in southern Nigeria: radiation use efficiency, soil moisture dynamics, and yields of component crops

Open Access Article; Published online: 30 Apr 2022Efficient utilization of incident solar radiation and rainwater conservation in rain-fed smallholder cropping systems require the development and adoption of cropping systems with high resource use efficiency. Due to the popularity of cassava-maize intercropping and the food security and economic importance of both crops in Nigeria, we investigated options to improve interception of photosynthetically active radiation (IPAR), radiation use efficiency (RUE), soil moisture retention, and yields of cassava and maize in cassava-maize intercropping systems in 8 on-farm researcher-managed multi-location trials between 2017 and 2019 in different agro-ecologies of southern Nigeria. Treatments were a combination of (1) maize planting density (low density at 20,000 maize plants ha-1 versus high density at 40,000 maize plants ha-1, intercropped with 12,500 cassava plants ha-1); (2) fertilizer application and management targeting either the maize crop (90 kg N, 20 kg P and 37 kg K ha-1) or the cassava crop (75 kg N, 20 kg P and 90 kg K ha-1), compared with control without fertilizer application. Cassava and maize development parameters were highest in the maize fertilizer regime, resulting in the highest IPAR at high maize density. The combined intercrop biomass yield was highest at high maize density in the maize fertilizer regime. Without fertilizer application, RUE was highest at low maize density. However, the application of the maize fertilizer regime at high maize density resulted in the highest RUE, soil moisture content, and maize grain yield. Cassava storage root yield was higher in the cassava fertilizer regime than in the maize fertilizer regime. We conclude that improved IPAR, RUE, soil moisture retention, and grain yield on nutrient-limited soils of southern Nigeria, or in similar environments, can be achieved by intercropping 40,000 maize plants ha-1 with 12,500 cassava plants ha-1 and managing the system with the maize fertilizer regime. However, for higher cassava storage root yield, the system should be managed with the cassava fertilizer regime

Developing recommendations for increased productivity in cassava-maize intercropping systems in southern Nigeria

Open Access Article; Published online: 31 Aug 2021Cassava-maize intercropping is a common practice among smallholder farmers in Southern Nigeria. It provides food security and early access to income from the maize component. However, yields of both crops are commonly low in farmers’ fields. Multi-locational trials were conducted in Southern Nigeria in 2016 and 2017 to investigate options to increase productivity and profitability through increased cassava and maize plant densities and fertilizer application. Trials with 4 and 6 treatments in 2016 and 2017, respectively were established on 126 farmers’ fields over two seasons with a set of different designs, including combinations of two levels of crop density and three levels of fertilizer rates. The maize crop was tested at low density (LM) with 20,000 plants ha−1 versus high density (HM) with 40,000 plants ha−1. For cassava, low density (LC) had had 10,000 plants ha−1 versus the high density (HC) with 12,500 plants ha−1.; The fertilizer application followed a regime favouring either the maize crop (FM: 90 kg N, 20 kg P and 37 kg K ha−1) or the cassava crop (FC: 75 kg N, 20 kg P and 90 kg K ha−1), next to control without fertilizer application (F0). Higher maize density (HM) increased marketable maize cob yield by 14 % (3700 cobs ha−1) in the first cycle and by 8% (2100 cobs ha−1) in the second cycle, relative to the LM treatment. Across both cropping cycles, fertilizer application increased cob yield by 15 % (5000 cobs ha−1) and 19 % (6700 cobs ha−1) in the FC and FM regime, respectively. Cassava storage root yield increased by 16 % (4 Mg ha−1) due to increased cassava plant density, and by 14 % (4 Mg ha−1) due to fertilizer application (i.e., with both fertilizer regimes) but only in the first cropping cycle. In the second cycle, increased maize plant density (HM) reduced cassava storage root yield by 7% (1.5 Mg ha−1) relative to the LM treatment. However, the negative effect of high maize density on storage root yield was counteracted by fertilizer application. Fresh storage root yield increased by 8% (2 Mg ha−1) in both fertilizer regimes compared to the control without fertilizer application. Responses to fertilizer by cassava and maize varied between fields. Positive responses tended to decline with increasing yields in the control treatment. The average value-to-cost ratio (VCR) of fertilizer use for the FM regime was 3.6 and higher than for the FC regime (VCR = 1.6), resulting from higher maize yields when FM than when FC was applied. Revenue generated by maize constituted 84–91% of the total revenue of the cropping system. The highest profits were achieved with the FM regime when both cassava and maize were grown at high density. However, fertilizer application was not always advisable as 34 % of farmers did not realize a profit. For higher yields and profitability, fertilizer recommendations should be targeted to responsive fields based on soil fertility knowledge

Key benefits of dexamethasone and antibody treatment in COVID-19 hamster models revealed by single cell transcriptomics

For COVID-19, effective and well-understood treatment options are still scarce. Since vaccine efficacy is challenged by novel variants, short-lasting immunity and vaccine hesitancy, understanding and optimizing therapeutic options remains essential. We aimed at better understanding the effects of two standard-of-care drugs, dexamethasone and anti-SARS-CoV-2 antibodies, on infection and host responses. By using two COVID-19 hamster models, pulmonary immune responses were analyzed to characterize effects of single or combinatorial treatments. Pulmonary viral burden was reduced by anti-SARS-CoV-2 antibody treatment, and similar or increased by dexamethasone alone. Dexamethasone exhibited strong anti-inflammatory effects and prevented fulminant disease in a severe disease model. Combination therapy showed additive benefits with both anti-viral and anti-inflammatory potency. Bulk and single-cell transcriptomic analyses confirmed dampened inflammatory cell recruitment into lungs upon dexamethasone treatment, and identified a specifically responsive subpopulation of neutrophils, thereby indicating a potential mechanism of action. Our analyses confirm the anti-inflammatory properties of dexamethasone and suggest possible mechanisms, validate anti-viral effects of anti-SARS-CoV-2 antibody treatment, and reveal synergistic effects of a combination therapy, thus informing more effective COVID-19 therapies

Dye-modified and Photoswitchable Macrocycles by Multiple Multicomponent Macrocyclizations Including Bifunctional BuildingBlocks (MiBs)

The multiple multicomponent macrocyclization including bifunctional building blocks (MiB) strategy is suitable to obtain macrocycles with inherent dye or photoswitchable subunits. Provided as dicarboxylic components in Ugi-MiBs, these functional subunits can be combined with natural like biarylether and peptoid moieties. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA

On-farm assessment of cassava root yield response to tillage, plant density, weed control and fertilizer application in southwestern Nigeria

Cassava is growing in importance in Nigeria as a food and industrial crop. Current yields are low due to poor soil fertility and because farmers do not use improved germplasm, clean planting material, or improved crop management in Nigeria. To provide feasible agronomic recommendations targeting increased root yield, the effects of tillage intensity, fertilizer application, plant density and weed control were tested in 230 farmers’ fields in southwestern Nigeria over two years. In 2016, tillage treatments were zero, single and double passage with a disc plough, followed by ridging (soil shaping) versus leaving the soil flat. Fertilizer application at 75:20:90 kg ha−1 NPK was tested against a control and two plant densities (10,000 versus 12,500 ha−1) were compared. In 2017, plant density at 10,000 ha−1 and double plough were excluded, while pre- and post-emergence herbicide application versus farmer’s choice of weed control (i.e. manual weeding using hand hoe) was introduced. Cassava was harvested at 12 months after planting, and yields were recorded as fresh root mass. In 2016, double plough (15.9 Mg ha−1) had a minor advantage over single plough (14.3 Mg ha−1), while zero plough produced 12.9 Mg ha−1 (P < 0.001). Ridging increased yield significantly (P < 0.01) by 2.3 Mg ha−1 after single and zero plough, but not after double plough. Across tillage treatments, planting at 12,500 plants ha−1 and fertilizer application increased yields by 1.5 and 4.2 Mg ha−1, respectively. In 2017, ridging resulted in a yield increase of 1.7 Mg ha−1 after single plough and 5.6 Mg ha−1 after zero plough. Fertilizer application increased root yield by 2.9 Mg ha-1 across tillage treatments. The use of herbicides negatively affected cassava yields in zero plough fields, compared with manual weeding. After ploughing, yield in herbicide based and manual weed control were not different. Cassava root yield response to tillage intensity strongly varied across fields, with low-yielding fields commonly responding less frequently to tillage. We conclude that unresponsive fields require measures other than increased tillage intensity to increase cassava root yields and that cost-intensive tillage operations must be targeted to responsive fields together with fertilizer application and improved weed control.ISSN:0378-4290ISSN:1872-685