Phenological characteristics, wool yield and quality of three selected provenances of Calotropis procera (Ait) in the South Eastern drylands of Kenya

Abstract

Calotropis procera is a dryland species which produces wool. In order to domesticate the species for wool production, a study was undertaken to evaluate growth, phenology and wool productivity of selected provenances of C. procera in the drylands of South Eastern Kenya. The research site was located at South Eastern Kenya University (SEKU) off Kwa Vonza, Kitui County, Kenya. Geographically, it lies at 01.313580S, 037.755460E & 01.314220S, 037.755760E at an elevation of 1173m above sea level (a.s.l.). The objectives of the study were to: i) determine the germination and early growth of three C. procera provenances in three soil types under nursery conditions, ii) to determine growth and phenological characteristics of three provenances under field conditions and at different spacing, iii) to quantify seasonal wool yield and quality from three provenances and iv) determine soil chemical characterization of the study site. The experiments were done at nursery and field levels. The experiments were done at nursery and field levels. The nursery and field experiments were laid out in a randomized complete block design and replicated three times. The nursery media treatments were three provenances and three soil media while field treatments were three provenances and three spacing levels. At the nursery, data on germination energy, energy period, germination rate, germination value and seedlings mortality were collected. Field data included growth data, phenological data, soil data and plant tissue data. Charts were generated to depict germination attributes. Computations of germination values were done using Czabator and Djavanshir and Pourbeik methods. Correlation analysis of germination attributes were also done. Seedling leaf production and height data were subjected to analysis of variance (ANOVA) and means separated using Tukey’s test (post hoc, p < 0.05). The field data was subjected to ANOVA to detect significant statistical differences (p < 0.05). Wool quantification and wool quality analysis were done in the laboratory. ANOVA was applied to assess the significance of variations in the soil chemical properties, plant tissue data, C. procera provenances and spacing variables in relation to the field plots. Tharaka provenance and sand soil had the highest germination energy of 76% and 83%, respectively, and a similarly high germination value of 87.67% and 86.21%, respectively. Analysis of Variances for branching indicated significant differences (p<0.05) with Baringo provenance recording a p-value of 0.043, Kibwezi, 0.01 and Tharaka, 0.0001. Dancun Multiple Range Test (DMRT) showed no significant differences in diameter growth for all the three provenances though height growth was significant (p < 0.05). All the three provenances showed strong and positive correlations (Pearson, p <0.01) for branching, DBH and height with Baringo recording rs=0.975, Kibwezi (rs=0.988) and Tharaka (rs=0.996). Flowering was characterized by clear-cut phenophases. Spearman rank correlations between wet seasons and flowering ranged from 0.89-0.96 and were highly significant. Growth, flowering and fruiting was impeded by periodic attack by Aphis nerii. 1.5*1.5m spacing level had highest wool production per Ha, followed by 2*2m then 3*3m, while 3*3m spacing gave the highest amount of wool per plant. Despite the fact that C. procera wool quality compared relatively well with that of cotton, spinning of the wool presented a challenge. There were no significant differences in subplots soil chemical properties. The study concluded that C. procera can be grown as a plantation crop with 1.5*1.5m spacing being the most appropriate from the economic perspective. Attack of C. procera by Aphis nerii is a major challenge in adopting the species as a plantation crop while failure of the fibres to separate during spinning presents a challenge in large scale use of the wool in textile industry. The study strongly recommends use of normal nursery soil (forest soil) due to its ability to promote early growth. Further, seeds for raising plantation stock should be obtained from the nearest source to reduce effects of seed transfer distance. Further research on improvement of the spinning properties of the wool is strongly recommended.