Characterisation and diallel analysis of commercially planted cotton (Gossypium hirsutum L.) germplasm in Tanzania
Abstract
English: 1. Thirty cotton varieties were studied. Seven parents generated 21 F1 diallel progenies.
The main objective was to evaluate genotypes through oil content, fatty acids,
morphological and molecular characteristics. Statistical procedures were performed with
Agrobase, NCSS and NTYSS computer programmes. Correlation, heterosis, heritability,
G x E interaction and stability values were obtained. Stability across four environments
was analysed by five stability measures, that of Shukla, Wricke, Lin and Binns, Eberhart
and Russell and the AMMI analysis.
2. Significant differences were observed for oil and fatty acids content. Oil content results
revealed an average of 20.23%. The ratio for polyunsaturated:saturated fatty acid was
2:1 and for unsaturated:saturated 3:1. The predominant fatty acids were linoleic,
palmitic, oleic, stearic, myristic, palmitoleic, arachidic and behenic. Palmitic fatty acid
was high while oleic and stearic fatty acids were low for almost all varieties studied. Oil
and fatty acid content were significantly influenced by the environment. CIM 70 and
Cyto 12/74 can be selected as parents for increased oleic and stearic fatty acid and
Stoneville 506 as a parent for reduced palmitic fatty acid, increased oleic, stearic and
linolenic fatty acids in hybridisation.
3. ANOVA results indicated significant differences between varieties for all agronomical
characteristics studied, where NTA 93-21 and NTA 93-15 were the best performers almost
for all characteristics. Genetic distances for morphological (qualitative characteristics)
analysis ranged from 0.18 to 0.80. Two major groups, one including many varieties from
Africa and the other including varieties from the USA, were revealed.
4. AFLP analysis showed high genetic similarities (0.85 to 0.98). Varieties were
distinguished according to pedigree and origin. The increased genetic similarity
observed, indicates the need for the introduction of more diverse cotton material.
Comparison of agronomical and AFLP markers for determining genetic diversity indicated that genetic similarities between varieties were low for agronomical compared
to AFLP markers. The correlation coefficient between AFLP analysis and agronomical
genetic similarities was not significant,
5. Highly significant differences between genotypes over environments were observed and
NTA 93-21 crosses outperformed the seven parents for almost all characteristics. The
parent Okra leaf performed poorly for many characteristics. Trial sites Ukiriguru
followed by Kanziga were high yielding environments.
6. Combining ability analysis results indicated significant variation in GCA estimates
among parents for different characteristics. Genotypes having high positive GCA
estimates for yield components exhibited negative GCA estimates for fibre quality,
excluding NTA 93-21. Some combinations indicated positive and significant SCA
effects for seedcotton, boll weight, GOT and lint yield. The GCA/SCA ratios for most of
the studied characteristics were larger than one.
7. Correlation among characteristics indicated highly significant positive and negative
correlations. The observed high and significant GCA and SCA effects for those
characteristics are promising for cotton population improvement. Positive heterosis for
boll weight was observed for more than 90% of the combinations. Hybrids with high
SCA values presented high values of heterosis. Heritability values for the studied
characteristics were moderate to high.
8. The combined ANOVA over four environments indicated significant differences
between genotypes and locations for all characteristics. The percentage contribution of
location to total variation was high compared to genotype variation except for a few
characteristics. Highly significant differences of G x E for lint yield and fibre strength
were observed.
9. Three stability procedures (Wricke, Shukla and ASV) identified similar stable
genotypes. Eberhart and Russell’s procedure, was in harmony with the above three
methods but with some divergence. Cultivar superiority measure deviated from the other
four measures. Therefore the procedures of Wricke, Shukla and AMMI can be applied
for cotton stability studies. Afirkaans: 1. Dertig katoen cultivars is gebruik in die studie. Sewe ouers het 21 F1 dialleel nageslagte
gegenereer. Die hoof doelwitte was om die genotipes te evalueer deur bepaling van olie
inhoud, vetsure, morfologiese en molekulêre eienskappe. Statistiese prosedures is
uitgevoer met Agrobase, NCSS en NTYSS rekenaar programme. Korrelasie, heterose,
oorerflikheid, GxE interaksie en stabiliteitswaardes is bereken. Stabiliteit is oor vier
omgewings getoets met vyf stabiliteitsmetings, die van: Shukla, Lin en Binns, Eberhard
en Russel en AMMI.
2. Betekenisvolle verskille is waargeneem vir olie en vetsuur inhoud. Olie inhoud was
gemiddeld 20.23%. Die verhouding van polie-onversadigde:versadigde vetsure was 2:1
en onversadig: versadig was 3:1. Die oorwegende vetsure was linoleïen, palmitien,
oleïen, stearien, miristien, palmitoleïen, eikosanoë, en dokosanoë suur. Palmitien suur
was hoog, terwyl oleïen en stearien vetsure baie laag was vir meeste inskrywings. Daar
was ‘n groot omgewingseffek op olie en vetsure. CIM 70 en Cyto 12/74 kan gebruik
word as ouers vir verhoogde oleïen en steariensuur inhoud en Stoneville 506 as ouer vir
verlaagde palmitiensuur, verhoogde oleïen, stearien en linoleïensuur in kruisings.
3. ANOVA resultate het betekenisvolle verskille aangetoon tussen cultivars vir gemeette
agronomiese eienskappe. NTA 93-21 en NTA 93-15 het die hoogste waardes gehad vir
byna al die eienskappe. Genetiese afstande vir morfologiese (kwalitatiewe eienskappe)
het gewissel van van 0.18 tot 0.80. Twee hoofgroepe, een met die meeste inkrywings van
Afrika en die ander met inskrywings van die VSA is gekry.
4. AFLP het hoë genetiese ooreenkomste getoon (0.85 tot 0.98). Cultivars is onderskei
volgens hulle stamboom en oorsprong. Hierdie hoë genetiese ooreenkoms het aangedui
dat meer diverse katoen materiaal gebruik moet word. Vergelyking van agronomiese en
AFLP merkers vir genetiese diversiteit het getoon dat genetiese ooreenkomste vir
agronomiese eienskappe tussen cultivars laag was in vergelyking met die AFLP merkers.
Die korrelasie koeffisiënt tussen die AFLP’s en agronomiese merkers was nie
betekenisvol nie. 5. Hoogs betekenisvolle verskille is gesien tussen genotipes oor omgewings, en NTA 93-21
kruise het die sewe ouers oortref vir byna alle eienskappe. Die ouer “Okra leaf” het
swak presteer vir baie eienskappe. Ukiriguru gevolg deur Kanziga was die hoogste
opbrengs omgewings.
6. Kombineervermoë analise resultate het betekenisvolle variasie vir GCA waardes
aangetoon. Genotipes wat hoë positiewe GCA waardes gehad het vir opbrengs
komponente het negatiewe GCA waardes gehad vir veselkwaliteit, behalwe NTA 93-21.
Sommige kombinasies het positiewe betekenisvolle SCA effekte gehad vir saadkatoen,
bolgewig, GOT en lintopbrengs. Die GCA/SCA verhoudings vir meeste gemeette
eienskappe was meer as een.
7. Daar was hoogs betekenisvolle positiewe en negatiewe korrelasies tussen eienskappe.
Die hoë en betekenisvolle GCA en SCA effekte vir hierdie eienskappe is belowend vir
toekomstige verbetering van katoen populasies. Positiewe heterose is gesien vir
bolgewig in meer as 90% van die kombinasies. Basters met hoë SCA waardes het hoë
heterose waardes gehad. Oorerflikheidswaardes vir die gemeette eienskappe was
gemiddeld tot hoog.
8. Die gekombineerde ANOVA oor vier omgewings het betekenisvolle verskille tussen
genotipes en omgewings aangetoon vir alle eienskappe. Die persentasie bydrae van
omgewing tot totale variasie was hoog in vergelyking met die bydrae van die genotipes
behalwe vir ‘n paar eienskappe. Hoogs betekenisvolle verskille vir GxE vir lint opbrengs
en veselsterkte is gesien.
9. Drie stabilteitsprosedures (Wricke, Shukla en ASV) het dieselfde stabiele genotipes
uitgewys. Eberhart en Russel se presedure was baie dieselfde as die ander metodes met
enkele afwykings. Cultivar superioriteits meting het afgewyk van die ander vier
metodes. Daarom kan Wricke, Shukla en die AMMI prosedures gebruik word vir katoen
stabiliteitsstudies.