Having inadequate roughages in cold areas in Tanzania? Consider forage oat and barley

Proper livestock feeding is key to improving the livestock sector in sub-Saharan Africa. Limited availability of well-performing forage technologies matched with production environment and context is often a constraint to increase forage quality and quantity for livestock productivity. To contribute towards forage technologies for cold areas, we selected four promising small grain varieties and evaluated them in 2020-21. They included two (Conway, Glamis) oat varieties and two (Rihane, Kounouz) barley varieties. In two village sites in Mufindi District in the southern highlands of Tanzania, we established trials in a randomised complete block design replicated three times. While the cultivars produced similar dry matter yields (t/ha), they returned significantly different crude protein (CP%), Neutral Detergent Fiber (NDF%) and in vitro organic matter digestibility. Digestibility was in the order Glamis Conway Kounouz Rihane, while crude protein yield (t/ha) was in the order Glamis Kounouz Rihane Conway. Based on dry matter and crude protein yields and digestibility, Glamis oat would be the most preferable in the study area and other similar ecologies

Physiological and productivity evaluation of Napier grass ('Pennisetum purpureum' Schumach.) cultivars under variable water supply, temperature and carbon dioxide conditions

Grasses have always been and will continue to be the most important resources for humans and their domestic animals. This study focused on one species of grass, Napier ('Pennisetum purpureum' Schumach.), that is valuable for fodder in both tropical and sub-tropical regions of the world. Napier grass cultivation is likely to increase, especially in east Africa, associated with the increase in human population coupled with a growing demand for livestock products. However, because the present arable land is fully committed, cultivation is expanding into marginal areas. These areas are usually characterised by high temperatures and reduced precipitation, likely to be adversely impacted by global warming associated with increased atmospheric CO₂ levels. This study was designed to increase understanding about how different Napier grass provenances respond to reduced water supply through rainfall and rising temperatures and their impacts on herbage productivity and quality. Such understanding would guide recommendations for farmers in these marginal areas to improve Napier grass management. Techiniques in tissue water status and gas exchange were applied to assess if they could be effective predictors of herbage yield and quality in Napier grass when subjected to water-stress and high temperature stress. The project was implemented in three phases: (1) a glasshouse study that tested the physiological techniques on two Australian cultivars, (2) field trials that tested the techniques on 10 acessions of Napier grass in two contrasting environments in Kenya, and (3) glasshouse study comparing Napier grass (C₄) with a common reed (C₃) subjected to water and heats tress and exposed to high atmospheric CO₂ concentrations

Water relations in two cultivars of Napier grass under variable water supply and temperature conditions

Napier grass ('Pennisetum purpureum' Schumach.) is the main fodder for the dairy industry in eastern and southern Africa as in many other tropical/subtropical regions of the world. Plant water relations were assessed for two cultivars of Napier grass; Local and Bana, the latter being an infertile hybrid between 'P. purpureum' and 'P. glaucum'. Plants were grown in a controlled environment at diurnal maximum temperatures of either 25 or 35°C to assess their tissue water relations in response to variable water supply (25, 50 or 100% field capacity) to mimic current and possible future climatic conditions in east Africa. At 25% watering and 25°C Local had higher midday relative water content (RWC) than Bana, but not at 50 or 100% field capacity, at which RWC was higher for Bana than for the Local. At the cooler 25°C, Bana attained a leaf water potential (LWP) minimum of -2.88 MPa at 25% watering, while Local had -2.27 MPa. At 100% watering and 35°C, Bana had higher RWC and LWP than Local at 25%. In a hotter environment, Bana appears to maintain higher water status than Local at 25% when soil is at field capacity while other watering responses appear similar for both cultivars

Use of plant water relations to assess forage quality and growth for two cultivars of Napier grass ('Pennisetum purpureum') subjected to different levels of soil water supply and temperature regimes

Napier grass ('Pennisetum purpureum' Schumach.) is an important fodder and relatively drought-tolerant crop in tropical and subtropical regions, especially in developing countries. For this and other species, tools are needed for identifying drought-tolerant cultivars to aid selection for semi-arid environments. We determined tissue water status, carbon assimilation, biomass yield and forage quality for Napier grass cvv. Bana and Atherton grown in bins and subjected to three soil-water supply levels (100, 50 or 25% of field capacity) in glasshouses set at either low (15-25°C) or high (25-35°C) temperature regimes, over three growing cycles. Our aim was to explore whether differences in leaf water potential (LWP) and carbon assimilation rates could be reliable indicators of the relative yield potential and forage quality of the two cultivars in environments prone to water and heat stresses. At the low soil-water supply of 25% and low temperature, Bana had lower (more negative) LWP and relative water content (RWC) than Atherton, while at 50% and 100% soil-water supply, Bana had a higher tissue water status. Under the high temperature regime, Bana had consistently more positive LWP and RWC than Atherton, but the differences were not significant. The two cultivars had a similar CO₂ assimilation rate (A) and there were no significant differences in the total dry matter yields over the three growing cycles. Water-use efficiency for above-ground biomass (kg ha⁻¹ mm⁻¹) was similar for both cultivars and was 28.5-35.1 under the low temperature regime and 16.9-22.9 under the high temperature regime. Neutral detergent fibre (NDF) was often higher for Bana at low water supply and low temperature than for Atherton, but the trend was reversed under the high temperature regime. Digestibility was generally improved under water-stressed conditions, and there was a positive correlation between NDF and both LWP and RWC measured at midday, but only under the low temperature regime. We conclude that LWP, RWC and A'', alone or together, are inadequate for selecting cultivars for dry and hot environments, because cultivars may differ in other mechanistic responses to water stress and high temperatures