Allelopathic Effect of Argel (Solenostemma argel L.) Additives on Seed Germination and Vigour of Two Snap Bean (Phaseolus vulgaris L.) Cultivars

Abstract

Two laboratory and one field experiments were conducted at the laboratory of Seed Administration and at the Farm of the Horticulture Sector, Federal Ministry of Agriculture and Forestry, Khartoum, Sudan, respectively, to study the allelopathic effect of argel additives on snap bean seed germination and vigour. Seeds of two bean cultivars (Paulista and Star2000) were sown on filter paper in petri dishes (18cm in diameter) and on sand medium in plastic pots (18cm in diameter) at the laboratory. On filter paper they were moistened with four concentrations of argel shoot water extract (0.2, 0.4, 0.6 and 0.8% w/v of distilled water and pots they were mixed as powder with sand to have the same concentrations w/w of sand, and irrigated with tap water at 70% of sand water holding capacity, in addition to a control with distilled (on filter paper) or tap water (in pots). In the field experiment the seeds were mixed with four different amounts of argel powder (20, 40, 60 and 80% w/w of seeds), in addition to a control without powder. The experimental units were in completely randomized for laboratory and completely randomized block (in split units) designs for field experiments, with three and four replications, respectively. The allelopathic effects were evaluated as seed germination and emergence percentage, seed vigour, germination or emergence rate and uniformity and growth (seedling length, number of leaves per seedling and seedling shoot fresh and dry weight).The results showed that the cv. Star2000 was more sensitive to argel extracts under field conditions than controlled condition (lab.). The reverse was noticed with cv. Paulista. Argel shoot extract or powder of concentration of 0.2% in the lab.or argel powder at 40% in the field increased seed germination or emergence percentage, vigour and seedling growth, whereas the reverse was noticed with the higher extract or powder concentrations compared to control. It was also noticed that the percentage of fungal infected seeds decreased with increased argel concentrations, where the lowest percentage of infected seeds was obtained by the highest argel concentration. It could be concluded that argel shoot extract or powder concentration 0.2% on filter paper or in pots (in lab), respectively, or powder at 40%.w/w of seed under field conditions had positive effect on snap bean seed germination, vigour and seedling growth, whereas, the higher ones had negative effect, irrespective of cultivar. Argel seed dressing of 40%w/w of seeds concentration could be used for improvement of field establishment of bean seedlings. Further studies are required to find which is more effective argel shoot extract or powder under field conditions.