Effects of Soil Type and Watering Regime on Performance of C4 Grass Ecotypes in A Simulated Semi-Arid Environment in Kenya

Abstract

Perennial grasses form the bulk of nutrition for livestock in semi-arid grassland ecosystems in addition to the provision of other ecosystem services such as carbon storage. A study was undertaken to evaluate the performance of ecotypes of two common perennial semi-arid grasses (Panicum maximum and Cenchrus ciliaris) under different soil types and watering regimes. Four indigenous perennial grass ecotypes namely Panicum maximum ISY, Panicum maximum TVT, Cenchrus ciliaris KLF and Cenchrus ciliaris MGD grown in three different soil types (ferralsols, fluvisols, and gleysols) and subjected to varied watering regimes (enhanced, depressed and normal) in greenhouse study. Interactively, soil types and watering regimes strongly influenced the morphological attributes among the grass ecotypes. Shoot and root biomass production among ecotypes was significantly (p < 0.05) higher in fluvisols subjected to enhanced watering and lower in gleysols under depressed watering. Shoot biomass of the different grass ecotypes was higher in fluvisols by between 7-34 % and 10-35 % compared to those grown in ferralsols and gleysols respectively. Similar trends were observed in rood biomass. Enhanced watering resulted in enhanced growth irrespective of the soil type. Depressed water regimes contributed significantly (p < 0.05) to a decline in biomass. Root biomass of the grass ecotypes was higher by between 50-89 % in fluvisols compared to ferralsols and between 41-163 % in gleysols respectively. Root: shoot ratios ranged from 0.41 - 1.73 in in the grass ecotypes with soil types and watering strongly driving biomass allocation patterns. These findings suggest that soil types and watering are key drivers of the productivity of the grass ecotypes, and precipitation variability is likely to have a strong influence on the productivity of semi-arid perennial grasses. Establishing appropriate grasses in suitable soils and with adequate moisture can enhance the success of fodder production and rangeland restoration initiatives for increased resilience.