The effects of fertilizers and mulberry (morus alba l. ) variety on cocoon and silk quality in Kenya
The study was carried out in two sites already with existing mulberry trees comprising three varieties, Kanva , Noi (Thailand), and Embu (local variety). The main objective of the study was to determine the effect of soil fertility and better mulberry varieties (grown locally) on cocoon and silk quality. The study compared the growth and yield performance of the three mulberry varieties being used by farrriers in silkworm rearing. It also involved comparisons of silk production using the three varieties and their quality response due to fertilizer (NPK) and manure treatments. These treatments were applied in 2 sites, ICIPE Farm at Kasarani and Thika government sericulture Farm. Growth of mulberry varieties due to response of different treatments, NPK alone, NPK and manure, manure alone, and control (no manure and no fertilizer) was determined. Growth measurements were taken in terms of height of shoots; number of shoots, and number of leaves per shoot. Additionally leaf analysis was carried out to compare leaf quality in terms of crude protein and crude fibre due to the different varieties and treatments. Groups of 50 silk worms were reared with leaf harvests from the different treatments. Larva weights were taken at 4thand 5th instars. After;spinning semi wet cocoon weight, dry weight, shell weight, and pupa weight were taken. Silk quality was based on cocoon weight, shell weight, length and weight of silk filament. These activities were done in two seasons, starting in the short rain season November 2004 to January 2005 and rearing in February 2005. The same procedure was repeated in the long rain season from March 2005 to July 2005 and rearing in August 2005, in order to evaluate the influence of seasonality on the parameters studied. Data was analyzed by Genestat statistical package using analysis of valiance (ANOV A) method. Means were separated by the least significant difference (LSD) according to Gomez and Gomez, 1984 at p:SO.05.The results showed that there were statistically significant effects of fertilizers and mulberry variety on mulberry growth performance, silkworm larva performance and consequently on cocoon weight and filament length. The cocoon weight was used to illustrate that there were significant effects of fertilizers and mulberry variety on economics of sericulture enterprise, fertilizer and manure giving higher gross margins than controls and Thailand variety giving higher gross margins than Embu variety.