Phenotypic characterization of Kenyan and south African spider plant (cleome gynandra l.) ecotypes
Abstract
Spider plant (Cleome gynandra L.) is an important leafy vegetable that has been used by local
African communities as a source of nutrition in their diets for many years. The plant has recently
attracted an increasing demand since it is highly nutritive and contains health promoting
bioactive compounds important in combating malnutrition and reducing human degenerative
diseases. Despite the great value of spider plant, there are limited efforts towards its
improvement especially in the area of phenotypic diversity. Spider plant has a rich genetic
resource base in Kenya and South Africa and knowledge of its phenotypic diversity in these
countries will aid on selection of accessions with desirable traits for breeding and conservation
purposes. The aim of this study was to determine the extent of phenotypic variation among
selected spider plant accessions from Kenya and South Africa and select those with desirable
qualitative and quantitative characters for future improvement. Field and greenhouse
experiments were conducted in 2013 and 2014 at the University of Nairobi‟s Kabete field
station, Kenya. A total of 32 spider plant accessions, 23 sourced from Kenyan genebank and nine
from South African genebank were used in characterization and evaluation. Both field and
greenhouse experiments were laid out as a randomized complete block design with three
replications. Eleven qualitative and quantitative traits based on modified FAO (1995) spider
plant descriptors were used in characterization. Qualitative characters evaluated included growth
habit, flower colour, stem colour, stem hairiness, petiole colour, petiole hairiness, leaf colour,
leaf pubescence, leaf shape, leaf blade tip shape, and number of leaflets per leaf. Quantitative
characters evaluated were days to 50% flowering, soil plant analysis development values, plant
height, stem girth, number of primary branches, leaf length, leaf width, single leaf area, number
of leaves per plant, number of pods per plant and seed yield per plant.
The qualitative and quantitative data were analyzed using DARwin software version 5.0 and
Genstat version 14. Shannon diversity index (H‟), multivariate methods of principal coordinate
analysis, principal component analysis and hierarchical clustering analyses of unweighted pair
group method of arithmetic averaging were assessed for all the qualitative traits. Analysis of
variance was performed at 5% level of significance for the quantitative data and variability
calculated using statistical measures of mean, standard deviation and coefficient of variation.
Correlation was also performed to estimate quantitative relationships among the traits
Estimates of Shannon-Weaver diversity index (H‟) for the qualitative characters assessed in the
field and glasshouse were generally high (H‟>0.500). The H' index indicated inter-country
diversity to be greater than the intra-country diversity. The second plane of principal coordinate
analysis separated the two groups of accessions (Kenyan and South African) clearly. Principal
component analysis identified seven important qualitative characters for characterizing spider
plant accessions. These were stem colour, stem hairiness, petiole colour, petiole hairiness, leaf
hairiness, leaf shape and number of leaflets per leaf. The hierarchical cluster analysis revealed
two major clusters (Cluster I and II) for the thirty two accessions grown in the field, with
clustering of accessions occurring along regional basis. Cluster I consisted of South African
accessions only while cluster II had mainly Kenyan accessions and two South African accessions
(accession numbers 1959 and 2289). The cluster phenogram grouped the glasshouse grown
accessions into three major clusters (Cluster I, II and III). Cluster I had only one accession,
GBK045436. Cluster II had two Kenyan accessions, GBK027195 and GBK027212. Cluster III
consisted mainly of a mixture of the Kenyan and South African accessions with two subclusters
(sub-cluster „a‟ and „b‟). Sub-cluster „a‟ had six South African accessions and two
Kenyan accessions. Sub-cluster „b‟ had a total of 21 accessions most of which were Kenyan
accessions.
The analysis of variance indicated significant differences (P<0.05) for most of the accessions
grown in the field and glasshouse. Number of leaves per plant was significant (P<0.05) and
positively correlated with SPAD values % (r = 0.34 and 0.03), stem girth % (r =0.59 and 0.29),
number of pods per plant % (r = 0.69 and 0.57) and seed yield per plant % (r =0.21 and 0.03) for
field and glasshouse grown accessions, respectively. However, number of leaves per plant
correlated both positively and negatively with days to flowering % (r = -0.17 and 0.12), leaf area
(r = -0.05 and 0.03), plant height % (r = 0.52 and -0.15) and number of branches per plant % (r =
0.35 and -0.09), respectively, for field and glasshouse grown accessions. Twelve accessions,
namely 1959, 2000, 2279, 2289, GBK027195, GBK027212, GBK031990, GBK031996,
GBK032302, GBK040606, GBK043261 and GBK045451 were found to be different from the
other accessions for important characters such as late flowering, high SPAD content, large leaf
area, high number of primary branches, high number of leaves per plant, high number of pods
per plant and high seed yield per plant. These accessions can therefore be used for future spider
plant improvement programmes through breeding in view of variety release.
Citation
Master of science in agronomyPublisher
University of Nairobi