Effects of water stress and substrate fertility on the early growth of Acacia senegal and Acacia seyal from Ethiopian Savanna woodlands

Abstract

Key message Acacia senegal and Acacia seyal present different drought stress coping mechanisms that are independent of substrate fertility. Higher substrate fertility increased aboveground plant growth, even with low watering. Abstract The potential of native African tree species for agriculture and forestry have not yet been thoroughly investigated. In this experiment, we studied the early growth of Acacia senegal and Acacia seyal plants in an experiment with two substrates of contrasting fertility (low/ high) and two watering frequency regimes (low = 24.40 l/m 2 per month, high = 48.80 l/m 2 per month). Our objectives were: (1) to study whether the mechanisms by which nutrients affect plant growth at the seedling stage operate differently when water availability varies, and (2) to look for differences in the growth strategies of the two species in early stages. Higher substrate fertility increased aboveground plant growth at the expense of roots in both water regimes. Though water stress significantly limited growth under both soil conditions, substrate fertility effects were relatively higher in plants with low water supply than in those with high water supply. However, even with low resources the root-to-shoot ratio was between 0.7 and 0.9, plants presented adequate nutrition and no mortality was observed. This indicates opportunistic mechanisms for water and nutrient use. A. seyal showed the lowest negative pre-dawn stem water potential value (-0.15 MPa) and shed nearly all leaves in the hottest month of the assay, which suggests a different drought avoidance strategy and adaptation to water stress than A. senegal. Both species can be produced successfully in local nursery conditions and can survive and thrive with low watering. The study also demonstrated that fast growing genotypes can be effectively isolated in nursery conditions.

Nursery Production of Pinus engelmannii Carr. with Substrates Based on Fresh Sawdust

“…The most widely used morphological attribute with which to estimate the quality of the seedlings is root collar diameter [8,11,34]. Because the survival and growth of plants in the field is associated with the root system of the seedling, the diameter has been defined as an important indicator [35,36].…”

Role of Acacia seyal on Selected Soil Properties and Sorghum Growth and Yield: A Case Study of Guba Lafto District, North Wollo, Ethiopia

“…Acacia seyal is one of the drought-tolerant agroforestry tree species found in eastern and southern Africa and native trees to the Sahelian zone of Africa [18,19]. It has a typical drought avoidance strategy and is adaptable to water stress conditions [20]. Unlike most other legume tree species, it nodules with both fast-growing (Rhizobium) and slowgrowing (Bradyrhizobium) bacteria strains which strengthen its role in nitrogen fixation and soil improvement ability [21].…”

Root Traits Determine Variation in Nonstructural Carbohydrates (NSCs) under Different Drought Intensities and Soil Substrates in Three Temperate Tree Species

“…Variations in climatic conditions, high temperatures, and low rainfall have caused most parts of the world to become dry, especially in temperate regions, resulting in tree death and forest ecosystem rapidly under favorable environmental conditions [38]. Conversely, they can also adapt to seasonal and unpredictable drought stress and can minimize their water loss by reducing their leaf size under drought conditions, thereby better protecting stems with a greater carbon cost from catastrophic hydraulic failure and withering than would be the case for typical hydraulic segmentation behavior [39,40]. However, the interspecific variation of fine root NSC levels in compound leaf species under different environmental conditions remains unclear, and the relationship between root morphological traits and NSCs has not been clarified.…”