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.