Distribution of commercial Mobydick (Gomphocarpus spp) grown in Kenya as revealed by morphological characterization

The genus Asclepias of Gomphocarpus subspecies commonly known as mobydick is currently grown commercially as a cutflower in Kenya. Asclepias refers to milkweed species grown in America and other Western worlds while Gomphocarpus refers to Asclepias species in Africa and Arabia continents. The varieties are distinguished mainly by boll characteristics which include size, shape, and plant height. In the farmers’ fields, Gomphocarpus physocarpus and Gomphocarpus fruticosus integrate to form a continuum and are difficult to distinguish. However, there is no precise data on the available commercial varieties of Gomphocarpus species grown and exported from Kenya. The species has recently been domesticated in Kenya but characterization has not been done. The objective of the study was to determine the distribution of major Gomphocarpus varieties in Kenya. A preliminary survey was done using the morphological characteristic of height to determine the prevalent type among farmers. The survey was conducted between April and June, 2011. The sampled areas were Machakos, Murang`a, Nandi, Nyeri, Bomet, Embu, Laikipia, Kisumu, Meru, Kajiado, Migori and Makueni districts. In order to get accurate information on the data collection sites, each farm was mapped by Global Positioning System (GPS) receiver; this instrument gave the altitudes (elevations), latitudes and longitudes of the sampled areas. A line level was used to establish the slope of the various sampled sites. Using boards graduated in the metric system, a distance of 10 metres between the boards was used. The board was moved up and down the slope until the spirit level showed that the string was horizontal. In this case, a difference in height of 10 cm would mean a slope of 1 %, whereas a height difference of 5 cm meant a gradient of 0.5% and 2.5 cm difference in height represented 0.25% gradient. A total of 145 farmers were selected at random and interviewed using a questionnaire. Soil samples were collected from sampled farms and analyzed in JKUAT laboratory using the hydrometer method. Materials used for soil structural analysis were water, sieves, hydrometer, sodium hexametaphosphate solution, amyl alcohol, soil dispersing stirrer, reciprocating shaker and soil textural triangle. The results showed that of the 145 farmers, 84.8% grew tall mobydick variety while 15.6 % grew the short variety. The results also indicate that 30.9% of all farmers growing the tall variety are in Machakos, Muranga (6.5 %), Nandi (11.4 %), Nyeri (14.6 %), Bomet( 7.3%), Embu (4.9 %), Laikipia ( 6.5%) , Kisumu (4.1%) , Meru (11.4 %) and the least were in Kajiado, Migori and Makueni each recording 0.8 %. As regards altitude, 84.8 % of all mobydick farmers grow the tall variety between 887-1388 m above sea level. Data collected on agro-ecological zones indicate that mobydick grows across UM4, LU4, UM2, LM4, SU3, LM3, LM1 and LM5 with 84.8 % of all farmers growing the tall variety. In conclusion, the tall variety is the most dominant of the commercial mobydick varieties among the Kenya farmers. The variety also dominates all agro-ecological zones at the current status.Key words: Asclepias, characterization, cutflower, distribution, Mobydic

Morphological characterisation of two endemic species of Gomphocarpus (Mobydick) in Kenya

The genus Gomphocarpus comprises 25 – 32 species that occur in Africa and the Arabian Peninsula. In Kenya, two common species; Gomphocarpus physocarpa and Gomphocarpus fruticosus are commercially cultivated as a cut flower for its inflated green bolls. As a comparison, Gomphocarpus physocarpa has larger and more rounded bolls whereas Gomphocarpus fruticosus have small bolls with a sharp pointed end. However, these two species can not be differentiated as they easily hybridize. No precise information on morphological or molecular characterization is available locally. The objective of the study was morphological characterization of commercial Gomphocarpus species grown in Kenya. Gomphocarpus germplasm was collected from Juja farm, Thika, Molo, Narok and Chumvi in Machakos. The experiment was laid out as randomized complete block design with three replications and five treatments per block. The collections were characterized for morphological diversity complimenting with principal component analysis (PCA) and cluster characters using the XLSTAT statistical software. The results showed no morphological variation on qualitative characteristics of leaf, growth habit and stem length. The coefficient of variations (CV) and standard deviations (SD) for all qualitative traits were zero. Boll length was positively correlated to boll weight with a factor of 0.355. Leaf length was inversely correlated to leaf width with a factor of negative 0.064. A PCA based on morphological traits of boll weight and length consistently separates populations of Gomphocarpus physocarpa and Gomphocarpus fruticosus and reveals a close relationship between them. All the qualitative characteristics of leaf colour, leaf shape, boll shape and flower shape were all clustered at the origin, displaying zero variations. The hierarchical clustering dendrogram revealed a 99.9% similarity among Gomphocarpus collections. The study showed that Gomphocarpus characteristics did not reveal any significant divergence in morphological qualitative traits observed. This could be an indication of low reproductive isolation in the collections. The two lines also hybridize, creating intermediate forms. Probably, there is need for complimenting similar work with other techniques such as DNA genetic markers to further accurately characterize Gomphocarpus germplasm existing in Kenya.Key words: Characterisation, cut flower, mobydick, morpholog

Molecular and Physiological Adaptations of Tea Plant in Response to Low Light and UV Stress

The sensory quality, economic value, and health functions of tea liquor depend on several metabolites in leaves of tea (Camellia sinensis L.), such as polyphenols (the most representative quality- and function-related compounds, especially catechins), caffeine, amino acids, aroma compounds, vitamins, and carbohydrates. The biosynthesis of these molecules is significantly affected by both management practices in the field and environmental factors, such as shading and ultraviolet (UV) stress. In this chapter, therefore, we review existing literature reporting the effects of shade and UV irradiances on tea plants with the aim to reappraise morphological, biochemical, physiological, and molecular responses found in this species. Cultivation of tea plants under shade can (i) induce anatomical and ultrastructural adaptations; (ii) influence leaf color, providing characteristic vivid greenness due to incremented chlorophyll content; (iii) decrease the risk of photoinhibition; and finally (iv) improve the quality of tea beverages by causing the reduction of the concentration of phenylpropanoids and caffeine (which contribute to astringency) while increasing the level of amino acids (the compounds that contribute to sweetness). However, the shade practice in tea is still subjected to controversy, and the correct managing of the shade practice is essential. Elevated UV irradiances, especially UV-B, can alter the plant morphology and affect several biochemical and physiological processes; most plant species respond to UV in a dose dependent manner. Protracted exposition to low UV-B doses (similar to UV peaks actually perceive by plants in the ambient) leads to an enhancement of phenylpropanoid metabolism and in particular stimulates the biosynthesis of UV-protecting flavonoids (mainly catechins). Conversely, UV-B doses much higher than those usually experienced in natural environment lead to the downregulation of the phenylpropanoid metabolism likely due to irreversible (to some extent) UV-triggered damages. The understandings of the reactions of tea plants to different light conditions, including situations of low light and high UV, are of pivotal importance to enhance both plant yield and tea quality by “driving” the accumulation of desired compounds in tea leaves