Characterization, propagation and management of Jojoba (Simmondsia Chinensis L.) in Semi-Arid Areas of Voi, Kenya

A THESIS SUBMITTED IN FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY OF SOKOINE UNIVERSITY OF AGRICULTURE. MOROGORO, TANZANIA.Jojoba is a dioecious desert shrub which produces oil of high quality equivalent to that of sperm whale. It is used mainly in the cosmetic and lubrication industry. Currently, there is low production of jojoba globally mainly due to high male to female ratio in the plantations since they are mainly established from seed. To overcome this problem, five experiments were set up with the aim of characterization, propagation and management of jojoba in semi arid areas of Kenya. The experiments included molecular characterization of mature bushes, sex determination in young jojoba seedlings using morphological traits, identifying the most appropriate plant growth regulators and management regimes of mother plants for propagation as well as field established seedlings. Randomized complete block design was used and the treatments were replicated three times. Analysis of variance was carried out using SAS statistical package whereas the differing means were separated using the LSD and DMRT. The experiments were carried out between 2012 and 2014. The results showed that the mature jojoba bushes had a low genetic diversity which was shown by PIC range of 0.2583-0.3748. Single leaf area morphological trait for male seedlings (4.4 cm2) was significantly higher (p < 0.05) compared with the females (3.2 cm2). Anatone gave superior rooting percent of 24.2% for cuttings compared with the other plant growth regulators, IBA, Roothom and the control which were 21%, 14.8% and 11.5% respectively. Consequently, the male genotypes, M2 and M1 showed significantly higher (p < 0.01) rooting percent of 37.6% and 24.2%, respectively compared with the females, F2 and F1 which were 7.6% and 2.2%, respectively. Management regimes performance of the mother plants did not have any significant effect on the rooting of cuttings in the polythene sheet tunnel. However, field established seedlings at 10 months showed that a combination of manure, irrigation and micro catchment was the best management regime since it gave the highest root collar diameter of 17.1 mm which was significantly higher (p < 0.05) compared with the micro catchment (12.2 mm) alone which was the least. On the other hand mcrocatchment and irrigation combination showed the highest height (86.4 cm) which was significantly higher (p < 0.05) compared with the control (61.5 cm) and all the single management regimes. Generally, different management regime combinations gave better growth compared with single management regimes. Due to the low genetic diversity, it is, therefore, recommended that superior genotypes be imported to increase the genetic diversity of jojoba in Kenya. Single leaf area morphological trait should be used for sexing in young seedlings in order to attain the right ratios of male to female of 1:10 respectively during field planting for improved productivity per unit area. On the other hand, Anatone is recommended for propagation of cuttings in a polythene sheet tunnel since it is also cheap and readily available from agri veterinary shops in urban centres. The male genotypes M2 and M1 are recommended for use in future propagation of cuttings although more screening is needed to identify a wide range of genotypes especially the females which are more valued due to their seed production. The ideal management regimes for field planted seedlings are combinations of manure, irrigation and micro catchment as opposed to single management regimes