Ethnobotanical study of edible oil crops as a companion of Sorghum bicolor L. Moench and biochemical genetic analysis of in situ and ex situ conserved Guizotia abyssinica (L.f .) Cass. germplasm from North Shewa and South Welo
Date
2001-06
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Abstract
South Wela and north Shewa are the center for the diversity of Sorghum bicolor. Sorghum is
cultivated in close association with oil crops mainly because of their combined uses in the
cultural feeding system of local people. The presence of multipurpose sorghum landraces in
the area have played a significant role for oil crop species diversity and their in situ
conservation, as each oil crop has its own unique domain in its combined use with sorghum. ·
The companionship of sorghum and oil crops is multidimensional, which includes multiple
cropping practices at the field level, multi-component food values. Their companionship is
deep rooted to the level of society's traditional beliefs and sacrifices and cultural life.
Guizotia abyssinica and Sesamum indicum are the most important oil crops of the area with
strongest companionship with sorghum both at the field level and home level. The stronger
the companionship of a given oil crop with sorghum at home level, the stronger the
companionship at field level too. This result is based upon (i) the interviews with local
farmers (both males and females) with heterogeneous age groups, and (ii) field survey
together with local farmers and the in situ team in order to collect data on the cropping
patterns and degree of companionship of sorghum and edible oil crops. Different
Agromorphological traits from six oil crops were analyzed for the purpose of obtaining the
level of variability among populations of each oil crop and correlation between traits.
Analysis of variance (ANOVA) and correlation analysis were conducted for quantitative
traits, while Shannon 's diversity index analysis was conducted for qualitative traits, to see the
potential genetic diversity of these oil crops. Capsule length, number of capsules per plant
and number of seeds per capsule are important for high yield in Sesamum indicum. Number
of branches per plant and number of heads per plant are the main traits that determine yield
in Guizotia abyssinica. In Carthamus tinctorius, number of capitulum per plant, which is a
primary trait to determine yield, did not show significant correlation with other traits studied.
In Brassica carinata, number of primary branches per plant, plant height and number of
seeds per capsule show significant positive correlation between themselves implying that
these traits might be important agronomic traits for high yield. Shannon diversity estimates
revealed that more than 7 4% of the total variation is due to within populations or area, for all
species analyzed. Multilocus enzyme electrophoresis (MLEE) was used to assess genetic variability in twenty in
situ conserved populations and twenty ex situ conserved populations of Guizotia abyssinca.
MLEE analysis at four enzyme loci scores 19 alleles. All 19 alleles were recorded in both in
situ and ex situ populations. Dendrograms constructed based on Nei 's genetic distance values
show that there is no clear differentiation between the two groups. All four loci were ·
polymorphic and characterized by significant heterozygote deficiency (P<0.001) and
significant deviation from Hardy-weinberg equilibrium (P<0.001). Mean Shannon's diversity
index between the two groups is too small which explained only 0.8% of the total variation.
Both group show almost the same level of diversity as revealed by both F-statistics and
Shannon's diversity index. Marked differentiation between populations (Fst= 0.313 and
0.237, for in situ and ex situ populations, respectively) was observed. Averaged overall
populations there was a mean number of alleles per locus (A) of 2.125 and 2.265, a mean
percentage polymorphic loci (P) of 72.50 and 76.25, and a mean observed heterozygosity
(Ha) of 0.249 and 0.265 for in situ and ex situ conserved populations, respectively, which
suggest a rather higher level of genetic diversity in ex situ populations than that of in situ
populations. The values of these variables, deferred considerably between populations, which
might be because of small sample size used and few number of loci studied. Although there
are some biases introduced due to small sample size used and few number of loci studied, the
parameters calculated have shown large level of genetic variability, which is the result of
hundreds of generations of continuous in situ conservation that have been reshaped by
farmers ' selection criteria.
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Keywords
ETHIOPIA, ETHNOBOTANY, SORGHUM, OIL CROPS, PLANT GENETICS, GENETIC RESOURCES, FOOD SECURITY, TRADITIONAL KNOWLEDGE, GENETIC DIVERSITY AS RESOURCE, INTERCROPPING, AGRICULTURAL PRACTICES