Malt barley is typically grown in dryland conditions in South Africa. It is an important grain after wheat, but little is known about its water requirements and, most importantly, how it responds to water stress. Determining when water stress sets in and how malt barley responds to water deficit during its growing season is crucial for improved management of crop water requirements. The objectives of this study were to evaluate the response of transpiration (T), stomatal conductance (SC), and leaf water potential (LWP) to water stress for different growth stages of malt barley and to characterise water stress to different levels (mild, moderate, and severe). This was achieved by monitoring the water stress indicators (soil- and plant based) under greenhouse conditions in well-watered and water-stressed lysimeters over two seasons. Water stress was characterised into different levels with the aid of soil water content ‘breaking points’ procedure. During the first season, at the end of tillering, flag leaf, and milk/dough growth stages, which represent severe water stress, plant available water (PAW) was below 35%, 56%, 14%, and 36%, respectively. LWP responded in accordance to depletion of soil water during the growing season, with the lowest recorded value to −5.5 MPa at the end of the milk/dough growth stage in the first season. Results also show that inducing water stress resulted in high variability of T and SC for both seasons. In the second season, plants severely stressed during the anthesis growth stage recorded the least total grains per pot (TGPP), with 29.86 g of grains. The study suggests that malt barley should be prevented from experiencing severe water stress during the anthesis and milk/dough stages for optimum malt barley production. Quantification of stress into different levels will enable the evaluation of the impact of different levels of stress on the development, growth, and yield of barley.

For adequate mitigation and adaptation measures, it is essential to have detailed analysis of droughts patterns. This study determined the i) occurrence and severity of droughts ii) drought recurrence frequencies and iii) drought trends across different agro-ecological zones in the Kingdom of Eswatini for the period 1981 to 2018. A Standardised Precipitation Index (SPI) computed from long-term precipitation data measured from six meteorological stations was used to determine drought occurrence and severity. Python software (Version 3.6) was applied on the SPI values to predict the recurrence of drought events over time in years. The SPI showed that in the Highveld, 42% of the droughts were moderate, 32% were severe and the remaining 26%, which all occurred post 1980 were extreme (SPI -2.34 to -2.82). The Middleveld had an even proportion of drought categories (29–35%). The Lowveld recorded 62% of moderate, 8% severe and 30% extreme droughts of which 70% occurred post 2000. Moderate droughts were found to recur every 4–5 years while extreme droughts are expected every 13–21 years. These findings are essential for mitigation and adaptation measures geared towards the adverse effects of droughts.

Global diminishing water resources, especially due to climate change have serious impacts on evaporation (E) from the soil surface, transpiration (T) from plants (crops) and grain yield, which relates to water use efficiency of different crops. A study was conducted at Kenilworth over two wheat cropping seasons (2007 and 2008) with the objectives of: (i) evaluating the effect of soils and seasons on T, E and yield, and (ii) relating these parameters to transpiration efficiency coefficient. The treatments included two soil types and two soil surface treatments (bare and mulched), which were all replicated four times. Weekly irrigation was done using a surface drip system while maintaining the water table at a constant depth. Soil water content was monitored using a neutron probe. Neither soils nor seasons were found to significantly influence the partitioning of evapotranspiration (ET), and T varied from 74 to 76% of ET while E varied between 24 and 26%. Surface treatments caused significant differences in grain yield in both seasons. Reducing evaporative loss improves the water productivity of wheat, which has an important implication in dryland farming.