Growth Characteristics of Kongwa Weed (Astripomoea hyoscyamoides Vatke verdc) Subjected to Different Soil Texture, in Kongwa District, Central Tanzania

Abstract

Kongwa weed (Astripomoea hyoscyamoides Vatke verdc) is a native annual noxious species to central party of Tanzania. It is able to grow under wide ecological conditions and forms dense stands, covering the top surface soil and causing change in both flora and fauna. The study was conducted to assess the growth performance and seed yield of Kongwa weed subjected to different soil properties collected from different land use types. The experiment was laid out in split-split plot design where three sites (Kongwa Ranch, Sejeli, and Ngomae) were the main factor, while subplots were three land-use types (grazing, bush, and croplands) and sub-sub plots contained soil textural types with three levels (Clay, loamy sand and sandy clay loam) replicated three times to make twenty-seven planted pots. Data for seed emergence were collected at an interval of 7days until 28 days after sowing, while the data for growth characteristics were collected 14 days intervals for 112 days after sowing. General Linear Model (GML) procedure of Statistical Analysis System (SAS) was used to analyze the data and Duncan Multiple Range test was used to compare the mean at 5% level. Results revealed that seed emergence, leaf length, leaf width, and seeds per fruit were not significantly affected by locations, land use types and textural soils. However, the highest stem girth of Kongwa weed were recorded in grazing land (7.4 mm stem girth plant^-1) followed by crop land (6.2 mm stem girth plant^-1) and the lowest was in the bush land soil (5.8 mm girth plant^-1). The mean Kongwa weed height, number of leaves, and branches were highest in sandy clay loam soil texture (81.2 cm height, 155 leaves and 10 branches), followed by loamy sand soil texture (74.3 cm height, 130 leaves and 11 branches) and short plant height (50.1 cm), number of leaves (82) and branches (5) were recorded in clay soil texture . Moreover, the results showed that few numbers of fruits (182), and seeds (728) of Kongwa weed were in the clay textural of soils than the loamy sandy and sandy clay loam textural soils. Poor growth and seed production of Kongwa weed were recorded in Buh land use types and clay soil interaction.  It is recommended that effective strategic control measures require a knowledge of weed growth characteristics. This can contribute development of effective integrated control and prevention strategies among a wider range of stockholders and policy makers.