A nature-based approach for managing the invasive weed species Gutenbergia cordifolia for sustainable rangeland management

Eco-friendly management of Parthenium hysterophorus

In sub-Saharan Africa, the invasive plant Parthenium hysterophorus (Parthenium) is threatening ecosystem integrity, biodiversity, and smallholder livelihoods. But, there is no single effective method of controlling it. Desmodium intortum, Lablab purpureus, and Medicago sativa were tested for their capacity to suppress Parthenium, as well as the allelopathic potential of Desmodium uncinatum leaf crude (DuLc) extract. While the study investigated the effect of DuLc extract concentrations on seed germination and seedling growth in laboratory, pot, field plot, it also assessed the effect of selected suppressive plants on Parthenium growth. It was found that high levels of DuLc concentrations and suppressive plants inhibited Parthenium germination and growth. When Parthenium was grown with suppressive plants, its growth was inhibited compared to when it was grown alone. When grown with all three test plants, the stem height and total fresh biomass of Parthenium seedlings were lowered by more than 60% and 59% in pots, and 40% and 45% in plots, respectively. Parthenium seed germination was decreased by 57% in plots, 60% in pots, and 73% in petri dishes at higher DuLc concentrations (i.e. 75% and 100%). Parthenium seedling stem heights were 36% (in plots) and 30% (in pots) shorter when sprayed with higher concentrations of DuLc. Overall, the findings of this study suggest that suppressive plants and those containing allelochemicals can be employed as a management tool to combat Parthenium invasion in sub-Saharan Africa, notably in Tanzania.

The effects of extreme climate on the invasive plant Gutenbergia cordifolia: implications for its future management in savannah ecosystems

The aim of this study was to assess the effects of varying water stress levels on morphological and physiological parameters of an invasive plant Gutenbergia cordifolia. The assessment was conducted in the screenhouse at the Nelson Mandela African Institution of Science and Technology following a completely randomized design (CRD). Both morphological and physiological parameters were variable under water stress levels. While the maximum (159 cm) and minimum (9 cm) plant heights for G. cordifolia were observed under flood and drought water stress respectively, its maximum root collar diameter of 5 mm and the minimum of 1.3 mm were observed under moderate flood and drought water stress respectively. Generally, the number of leaves was highest under moderate flood stress (194 leaves/plant), and lowest under drought stress (13 leaves/plant). Similarly, the largest and smallest leaf surface area of 9 × 10³ and 1 × 10³mm² were observed under flood and drought water stress respectively due to G. cordifolia's tendency to retain water when exposed to water stress through a reduction in number of leaves and leaf surface area when under drought stress condition. While a decrease in leaf chlorophyll was observed across water stress levels with the lowest chlorophyll levels of 0.02 under drought water stress, an increase in leaf anthocyanin levels (0.29 Abs g.DM^-1) was observed particularly under flood stress due to increased chlorophyll breakdown and plants' water stress, respectively. This study informs that extreme climatic events such as excessive floods will likely facilitate invasions by G. cordifolia leading to decreased biotic resistance of native communities in savanna rangelands. Efforts to manage G. cordifolia's effects in a changing climate must therefore include the development of strategies and action plans that account for catastrophic events like floods and drought.