Maize is an economically important crop in Africa including South Africa. To maintain and produce maize varieties with specific agronomic traits and qualities, management is required in the form of identity preservation (IP). Identity preservation is becoming increasingly important with the advent of modern biotechnology. The purpose of IP is to minimize gene flow of which the principal factor is pollen movement. Maize pollen movement has been previously studied measuring out-crossing, measuring pollen concentrations and computer modelling. In this study, genotypic detection of trapped pollen as well as the phenotypic observation of out-crossing was used. Field trials were performed at two geographic locations in South Africa and spatial as well as temporal isolation was used to ensure that surrounding maize production did not influence the result of this study. It was determined that although various methods of pollen preservation were not effective to maintain pollen DNA integrity, storage in CTAB buffer proved successful for up to nine months for PCR analysis. An inexpensive pollen trapping system was devised using Tween 20 coated on glass slides. From pollen trapping experiments it was determined that maize pollen, with a specific genotype, could be detected at up to 400 m from the source even though the pollen load on the traps was low. Phenotypic evaluation of out-crossing revealed a very high incidence (between 22.3 and 39.1%) of out-crossing between yellow and white adjoining maize rows, and decreased to 1% at a distance of 25 m, and thereafter was an average of 0.36% up to 81.6 m. The two geographic locations were not significantly different in terms of out-crossing data. The analysis of out-crossing data over distance, determined that distance is not solely responsible for the pattern of out-crossing. The analysis of weather data taken during the flowering period indicated that temperature and relative humidity were not significantly different across the different locations. However, wind differed significantly between the different locations with more relevant wind, regarding the orientation to maize plots, in Delmas than in Lichtenburg. Low levels of out-crossing were detected using PCR that would otherwise have remained undetected. The 35S promoter from the Bt gene was detected at 0.12 and 0.9%, respectively, across the different locations, in sampled cobs of white maize up to a distance of 2 m. The quantification of the Bt gene in yellow hybrid seed was consistent with expected values, taking the development of the yellow maize parent into consideration. During the course of this study different areas of research were identified that have not been addressed adequately in this or other studies, this includes, in hind sight, several ways in which the experimental design of this study could have been improved. The assessment of the impact of individual environmental variables on pollen longevity warrants a more detailed study. The correlation between pollen DNA viability and fertilisation potential should be further investigated. It would also be useful to have included data over multiple years but was not possible due to the time constraints of an M.Sc. In conclusion, this study has determined that maize pollen of a specific genotype can be detected at 400 m from its source and that even though out-crossing declines rapidly up to 25 m, out-crossing events average 0.36% up to 81.6 m. Out-crossing is determined by distance in conjunction with environmental factors, making geographic specific data important for region specific identity preservation requirements. This study makes an important contribution to available data on pollen movement, as no other published data is available for South Africa.

The objectives of the study were to evaluate different statistical methods to describe genotype x environment interaction over three years, with maize hybrids across several environments. The environment and soil variables have a major effect on the performance of maize hybrids in South Africa. The second objective was to evaluate and compare the different statistical stability models and procedures, to identify the best stability model to accurately assess and rank maize hybrids according to their stability over environments and years. The third objective was to describe genotype x environment interaction and the adaptation of maize hybrids to different environments over years. Twenty three maize hybrids were evaluated at 42 environments between 2001 and 2003 in the major maize producing areas in South Africa. Grain yield and other agronomic traits were determined but mean grain yield was used to determine stability with the following stability procedures: CV (coefficient of variation), Linn and Binns, Shukla, Wricke, Finlay and Wilkinson, Eberhart and Russell, and the ASV (AMMI stability value). The comparison of the procedures were done with Spearmanâs rank correlation coefficient and the significance determined with studentâs t-test. Linn and Binns cultivar performance measure ranked the hybrids, with high (Pi) values as the most stable. CRN 80-10 was ranked first, CRN 3505 ranked second and SNK 8520 ranked third. The unstable hybrids with low (Pi) values were SNK 6025, PHB 32A03 and PAN 6615. Linn and Binns procedure was not significantly correlated, with any of the other procedures. It was only significantly correlated with mean yield (r = 0.97332**), thus confirmed that it is more a measure of performance and not really a stability parameter. Finlay and Wilkinsonâs regression coefficient indicated that DKC 80-10, CRN 3505 and PAN 6568 showed average stability and were adapted to most of the environments. SB 7551, PHB 3203W and SA 7401 have below average stability and adapted to the higher yielding environments. DK 617, DKC 61-24 and SNK 8520 were of average stability but were specifically adapted to low yielding environments. This method was also not comparable to the other methods and was only positive and significantly correlated with CV. Shuklaâs stability variance indicated that CRN 3549, PAN 6615, DKC 63-20, PAN 6573 and SA 7401 were stable and SNK 2551, CRN 4760B, CRN 3505, PHB 3203W and SNK 8520 were unstable hybrids. DKC 80-10 was the highest yielding hybrid but only average on stability. This method compared well with the procedures of Eberhart and Russell, Nassar and Hühn, Wricke and the ASV (AMMI). The comparison of the rank correlations were all significant and positive. Shuklaâs and Wrickeâs methods had total correspondence (r = 1.000**). These methods will rank hybrids equivalently according to their stability. Wrickeâs ecovalence ranked CRN 3549, PAN 6615, DKC 63-20 and PAN 6573 as the most stable hybrids with SNK 2551, CRN 4760B, CRN 3505, and PHB 3203W as the most unstable hybrids. Wrickeâs ecovalence was positively and significantly correlated with Shukla, Eberhart and Russell, Nassar and Hühn and ASV. Eberhart and Russellâs deviation from regression indicated that CRN 3549, PAN 6615, SA 7401, DKC 63-20 and PAN 6573 were the stable hybrids. SNK 2551, CRN 4760B and CRN 3505 were the unstable hybrids. It corresponded with the methods of Shukla, Wricke, Nassar and Hühn and the ASV. Nassar and Hühnâs mean absolute rank method indicated PAN 6615, CRN 3549, SNK 6726 and DKC 80-10 as the stable hybrids. CRN 3505, CRN 760B, SNK 2551 and DKC63-20 were the most unstable hybrids. This method was significantly and positively correlated with Shukla, Wricke and Eberhart and Russell. It was not correlated with ASV, Linn and Binns and Finlay and Wilkinson. The AMMI stability value (ASV) ranked DKC 63-20, DK 617, DKC 61-24 en SB 7551 as stable. SNK 2551, CRN 4760B, PHB 3203W en CRN 3760 was unstable. ASV was significantly correlated with the methods of Shukla, Wricke and Eberhart and Russell. Die AMMI model 2 indicated Delmas (quadrant II), Petit, Meerlus, Bergville, Piet Retief and Ermelo (quadrant III) as the high yielding environments. DKC 80-10, CRN 4760B, PAN 6568, SNK 8520 and SA 7401 were adapted to the high yielding environments but specific to Delmas. CRN 3505, SB 7551, SNK 2551 and CRN 3549 are also adapted to high yielding environments but more specific to Petit, Meerlus, Bergville and Ermelo. Kroonstad, Kameel, Bothaville, Viljoenskroon and Rietgat are the average to low yielding environments and are clustered in quadrant I. DK 617, SNK 6726, DKC 63-20 and DKC 61-24 were adapted to these environments. Ficksburg, Wonderfontein and Ogies were clustered in quadrant IV and shown to be average to low yielding environments, hybrids that were specific adapted to these environments were PHB 3203W, PHB 32A03, DKC 71-21, PAN 6615 and PAN 6573. Die AMMI method successfully summarized patterns and relationship of the hybrids with the environments. AMMI indicated the genotype x environment interactions and clustered the hybrids according their adaptability to certain environments. The graphical AMMI biplot explained and described the hybridâs adaptation and interaction with the environments.

Sun lower (Helianthus annuus) is a commercially important crop plant. Susceptible plants in ected with lea rust (Puccinia helianthi) leads to great yield losses. The aim o this study was to identi y putative protein kinase genes rom a resistant sun lower cultivar that are involved in the early resistance response when the plant is in ected with lea rust. Several di erentially expressed cDNA ragments were isolated rom in ected resistant sun lower. One o these identi ied clones (D15) showed an 8.5 old induction o gene expression 3 h.p.i. in in ected resistant sun lower, while the expression in the susceptible in ected cultivar was repressed. A second 31 old activation was ound 15 h.p.i. This second induction most probably orms part o induced SAR in the unin ected plant tissue. This cDNA clone showed homology to several protein kinase genes. In addition, the gene is present as a single copy within the genomes o susceptible and resistant sun lowers. A polymorphism in size was however evident between the genes present in the two cultivars. Three other cDNA clones were also selected on the basis o their expression pro iles. These cDNAs showed homology to Apyrases, a Rac-protein and Xyloglucan endotransglycosylases respectively. The involvement o all our cDNAs in the activation o plant de ense however still needs to be con irmed.

The subject of this study is the family Amaryllidaceae with emphasis on 14 genera which represent six of the 15 tribes in this family. The genera are Amaryllis L., Ammocharis Herb., Boophone Herb., Brunsvigia Heist., Clivia Lindl., Crinum L., Crossyne Salisb., Cyrtanthus Aiton, Gethyllis L., Haemanthus, Hippeastrum, Narcissus L., Scadoxus Raf. and Strumaria Jacq. ex Willd. The Amaryllidaceae is a cosmopolitan, predominantly pantropical, family of petaloid, perennial or biennial monocots. The Amaryllidaceae form one of the climax groups in the Asparagales. They are probably more closely related to Alliaceae and Hyacinthaceae. The Amaryllidaceae is a large group consisting of about 860 species in 59 genera. Its centre of diversity is in Africa (19 genera) and South America (28 genera). Some genera also occur in the Mediterranean (8 genera) and temperate regions of Asia. Only one genus, Crinum L., is represented in both the Old and New Worlds because of seeds well adapted for dispersal over water. For this study a chloroplast gene and DNA region: matK and trnL-F, respectively, and a nuclear DNA region: ITS, were used in the phylogenetic reconstruction. All three give DNA sequences that are useful for comparing species and closely related genera. Despite a lack of consensus on generic limits and tribal delimitation within the Amaryllidaceae, cladistic analysis has only rarely been applied to problems in the family. Homoplasy for many conspicuous characters within some ge nera impedes the application of phylogenetic studies for the entire family. The combined trnL-F and matK matrix gave better results than the separate trnL-F analysis. The results of both the matK data and the combined matrix were well supported by bootstrap and jackknife. The sister status of the Eurasian/American/Mediterranean clades were better resolved in the separate matK analysis than the combined matrix. The indigenous tribes Amaryllideae, Haemantheae, Cyrtantheae and Gethyllideae were resolved and well supported in the separate matK and combined analysis. The results between the two combined matrices were very similar but the different tribes were better resolved in the combined matrix of all three DNA regions. In this study, the combined matrices indicated stronger bootstrap and jackknife support compared to the separate data sets of trnL-F, matK and ITS. Reported chromosome numbers of genera in the Amaryllidaceae indicates that variation between somatic chromosome numbers in each tribe is not high, except where hybridization may occur. Most of these somatic chromosome numbers agree with the given basic chromosome numbers that may occur in each tribe. As more becomes known of the southern African species in the family Amaryllidaceae, the lack of knowledge regarding chromosome morphology and behaviour becomes more apparent. In this study, the results of a cytogenetic study on several Cyrtanthus species are included. Chromosomes in this genus are large, as in the rest of the Amaryllidaceae. Variations in their karyotypes have been described. A somatic chromosome number of 2n = 2x = 16 was observed in most of the Cyrtanthus species except for two specimens of C. mackenii var. mackenii. A somatic chromosome number of 2n = 4x = 32 was indicated by these specimens. A tetraploid Cyrtanthus species has not been previously reported. However, this study did not support previous studies that ideograms vary among the different Cyrtanthus species and may be used in the identification of certain species. The variation in the ideograms was minimal and not sufficient for identification purposes. The results of this study strongly support those from previous studies and can be used in the classification of Amaryllidaceae.

Grain sorghum is an important cereal crop for food security in developing countries. The crop is mainly preferred due to its adaptability to harsh environments including extreme temperatures and water limiting environments. However, for grain sorghum to compete equally with maize, certain improvements must be made. The objectives of the study were to measure the 1) yield potential of genotypes 2) identify bird-resistance genotypes 3) compare Group I and Group III genotypes in terms of food quality characteristics. Thirty genotypes including two standards, developed by the Agricultural Research Council, Potchefstroom, South Africa were used. These genotypes were planted in Potchefstroom and Taung, in the North West province of South Africa. The experiment was laid out in a randomized complete block design with three replications. Data collected for yield potential included grain yield, seed weight per panicle, full panicle weight, and thousand seed mass. Data was analyzed per location and across locations using Agrobase, 2000. The results showed highly significantly differences among genotypes in the locations and across locations in all yield characteristics measured. The interaction between entry and location was highly significant. Genotypes were evaluated for bird resistance through the percentage grain yield loss. Percentage bird damage was highly significantly different between groups and among genotypes in Potchefstroom. The damage was severe in group I compared to group III. Taung resulted in 100% bird damage. Two hundred and fifty gram per sample was assessed in a Tangetial Abrasive Dehulling Device for abrasive hardness index (AHI), followed by milling and flour color assessment. The samples were not replicated except for endosperm texture, and grand means were used to compare the groups. Group I performed better than group III in terms of milling yields, flour color, AHI, percentage kernel removed and endosperm texture. These milling quality characteristics showed significant correlation with each other and most importantly correlated with endosperm hardness. Therefore, many food quality characteristics in sorghum are determined by endosperm texture. A 12% solution (flour and water) was used to analyze viscosity of the porridge using the Brabender ® Viskograph âEâ. The response of genotypes during cooking showed highly significant differences. Groups were highly significantly different for maximum viscosity, start of cooling period, breakdown, and setback and non-significant for beginning of gelatinization, end of cooling period, and end of final holding. Viscosity parameters measured were positively correlated to each other.

The aim of this study was to determine the inheritance and environmental factors that regulate stem strength in irrigation wheat. The strength of the stem is defined by its length and as an index of the function of the pressure which it takes to break the stem, the pith thickness of the stem wall at breaking point and the length of the internodes. In the first experiment a set of parents was evaluated to determine the differences amongst parents for stem strength and its components. The parents significantly differed in stem length and strength. Some parental genotypes had shorter and more solid stems. For the second experiment the same parental genotypes were used to create a diallel set of progeny. The progeny and the parents were planted in pots in the tunnel in a replicated experiment to evaluate plant height and stem strength. It was found that the variances for all characteristics were significant, but the additive component (general combining ability) was higher than the dominance component. The parents differed significantly in their ability to produce F1 progeny with stronger stems. The calculated heritability was high and significant, which showed that the best way to select for improved stem strength is to select amongst plants in the progeny of the parents with the highest combining ability for the desirable traits. The third experiment was done to determine the interaction of higher plant density and higher N fertilisation on the expression of stem strength. This experiment (parents and progeny) was planted in pots in a tunnel. It was found that genotype, plant density and N fertilisation had a highly significant effect on stem strength. The ability of the parents to produce progeny with strong stems differed. The parents with the solid stem phenotype and shorter stems generally produced progeny with stronger stems. The variance for general combining ability (additive genetic variance) is significant. The heritability for all characteristics was high, but higher in increased plant density or increased nitrogen application but with the highest expression where both plant density and nitrogen application were increased. This indicates that selection for stem strength should be more successful in populations with a higher plant density under high N conditions.

This study represents the first comprehensive genetic study based on local cultivars of Mozambique. Five cassava (Manihot esculenta Crantz) parents were crossed in a full diallel. The parents and F1 progeny were evaluated for eight agronomical and 17 morphological traits in two consecutive seasons. General combining ability (GCA) was higher than specific combining ability (SCA) for number of roots, root taste, fresh root yield, root pulp hardness and harvest index. Positive heterosis was seen for number of roots, fresh root weight and harvest index. Negative heterosis was present for cassava brown streak virus disease. Harvest index showed high broad sense heritability, which indicated that phenotypic variance was additive. The predictability ratio was close to unity, which confirmed that this trait is highly heritable, and determined by additive gene action. Cassava brown streak root necrosis had SCA effects significantly higher than GCA effects indicating the presence of non-additive genetic effects. A selection index comprised of the most relevant characters was compiled. Amplified fragment length polymorphism (AFLP) analysis showed high genetic similarity among 17 accessions. A total of 425 fragments were produced by eight primer combinations. Mocuba and Nikwaha were the most distinct among the accession and two heterotic groups were suggested. Morphological analysis showed genetic distance ranging from 0.105 to 0.833. The correlation coefficient between AFLP and agronomic clustering was not significant. The AFLP and morphological analysis did not group the accessions according to geographical origin. The principal component analysis provided diversity structure, suggesting the effectiveness of this analysis in genetic diversity studies. The narrow genetic similarity observed, indicates the need to introduce new cassava germplasm.

Maize is the dominant staple crop in most regions of Africa. The nutritional value of maize protein, however, is deficient in the essential amino acids such as lysine and tryptophan. This study was conducted to (1) investigate the level of variability among elite QPM inbred lines, (2) analyze combining ability of the inbred lines and G x E interaction of the resulting hybrids under stress and optimal conditions, (3) study the associations of parental genetic distances with F1 performance, heterosis and SCA of the hybrids under stress and optimal environments, and (4) investigate the effects of low N stress on endosperm modification, protein quantity and quality of QPM and identify best donor parents. The genetic variability of 35 maize inbred lines (32 QPM and three normal maize line checks) was studied using morpho-agronomic traits and SSR markers. Both methods indicated genetic variability among the lines. UPGMA cluster analysis based on morphoagronomic data grouped the inbred lines into four clusters and two outliers mainly based on grain yield, days to anthesis, plant height and leaf area. SSR markers grouped the inbred lines into six clusters which were different from the morpho-agronomic clustering. SSR markers grouped the inbred lines more efficiently in accordance with pedigree relationships. A diallel analysis of 15 QPM inbred lines showed significant GCA and SCA mean squares for most traits under optimal environments. GCA effects were significant while SCA effects were not significant for most traits across sites with drought and low N stress. Additive genetic effects were important under stress, and both additive and non-additive genetic effects were important under optimal conditions. Inbred lines VL054178, VL05482, VL05561, VL05483, CML511, CML159, CML491 and VL06375, which had good GCA effects for most traits under stress and non-stress conditions can potentially be used in QPM breeding programs in Africa and similar environments worldwide. Mean MPH ranged from -9.1% for days to silking to 112.7% for grain yield and HPH ranged from -12.0% for days to silking to 89.8% for grain yield. All the crosses showed negative MPH and HPH for days to anthesis and silking, and positive MPH for plant and ear height, number of kernels per row and kernels per ear. SSR marker-based genetic distance was positively and highly significantly correlated with grain yield; and negatively and highly significantly correlated with days to anthesis and silking. The correlations of SSR marker distance with heterosis and SCA were low to be of predictive value. Morphological distances were not useful in predicting heterosis and SCA effects of hybrids. Environment affected the correlations of genetic distance with hybrid performance, heterosis and SCA, with lower values under stress conditions. AMMI stability value and linear regression models were positively correlated in ranking the stability of QPM hybrids. AMMI analysis based on inbred line means and selected hybrids clearly discriminated the genotypes on the base of adaptation patterns. Hierarchical clustering based on hybrid grain yield and inbred line means grouped the 13 environments mainly according to geographical location and prevailing growing conditions. QPM hybrids showed higher levels of tryptophan content and protein quality index than the normal maize hybrids under both low N stress and optimal conditions. Low N stress increased the frequency of soft or poorly modified grains and decreased tryptophan and protein concentration in grain and increased protein quality index. Tryptophan concentration was more stable than protein concentration across low N stress and optimal conditions. Additive gene effects were primarily responsible for variation in endosperm modification and protein quality in the QPM inbred lines. Inbred lines VL05200, VL05468, VL054178 and CML144 were the best general combiners for endosperm modification; hence can be used as o2 donor parents. Information from the genetic diversity analyses of the inbred lines can be used for effective utilization of the inbred lines in the breeding programs for the formation of heterotic populations and development of desirable varieties. The inbred lines used in this study, in general, were found to be useful sources for genetic variability for the development of new genotypes for stress tolerance and the study confirmed the possibility of achieving good performances across stress and non-stress conditions in QPM germplasm. However, more breeding efforts should be devoted to the development of QPM inbred lines with better field performance and acceptable levels of protein quality and quantity under both stress and optimal conditions. Inbred lines identified as good o2 donors can be used for the conversion of well adapted normal maize genotypes into QPM counterparts.

Induced phytoextraction is an emerging soil remediation technology that makes use of soil amendments and high biomass crop species to accumulate and remove heavy metals from soils. The failure to rehabilitate an uranium trial mine on Rietkuil 307 in the Karoo Uranium Province of South Africa, has led to above normal concentrations of uranium (U), molybdenum (Mo) and arsenic (As) in topsoil in the vicinity of U ore stockpiles. A greenhouse evaluation was executed to assess the potential of citric acid to induce metal uptake in the shoots of Indian mustard [Brassica juncea (L.) Czern, cultivars: 211000 and 426308] and sunflower (Helianthus annuus L.) to decontaminate the low-level U (28 mg U kg-1 soil), Mo (4.1 mg Mo kg-1 soil) and As (8.9 mg As kg-1 soil) contaminated soil to background concentrations. A further greenhouse study was performed in a soil with high levels of metal concentrations; U (165 mg U kg-1 soil), Mo (125 mg Mo kg-1 soil) and As (49 mg As kg-1 soil), to assess the feasibility of phytoextraction on a high-level metal contaminated soil. Citric acid proved to be effective in enhancing shoot-U, -Mo and -As concentrations and the highest concentrations were observed in B. juncea 211000 (1788 mg U kg-1; 467 mg Mo kg-1; and 24 mg As kg-1) grown in the lowlevel contaminated soil. With a biomass yield of 5.51 tonnes per year for B. juncea 211000, it would take 9 to 14 years to decontaminate Mo and U on Rietkuil 307 soil to background concentrations. As a result of the low As solubility in soil and subsequent low shoot concentrations of the plant species, it is suggested that other measures for As remediation be investigated. Furthermore, plants grown in the high-level contaminated soil achieved considerably lower biomass yields and shoot-metal concentrations than in the low-level soil due to metal toxicity. Phytoextraction will, therefore, not be a feasible remediation technology on high-level U, Mo and As contaminated soils. These results suggest that citric acid induced phytoextraction may provide an environmentally friendly alternative for the decontamination of low-level U and Mo contaminated soils.

Kenaf (Hibiscus cannabinus L.) is one of the worldâs most economically important fibre crops. The traditional use of kenaf focuses on its fibre production, for the making of products such as ropes, sacks, canvases, and carpets. New applications of kenaf have been developed such as pulping and papermaking, board making, filtration media, potting media, animal feed, and oil absorption. The fibres are also processed for use in the automotive industry. Kenaf was introduced to South Africa during the last few years. The crop is being explored as a potential commercial crop for fibre production in South Africa. · The objectives of this study were to conduct glasshouse and field trials on commercial kenaf cultivars to evaluate morphological and agronomic differences between them; to compare the oil content and fatty acid composition of the seed of eight cultivars; to determine genetic relationships between commercial cultivars and nine wild type varieties and to determine the genotype x environment (G x E) interactions and stability of commercial cultivars. · Seeds were obtained from several sources and sown directly into pots. Seedlings were grown in a heat-controlled glasshouse. A field trial was also planted in another location. These plants were used in various investigations. · Two field trials were planted in two different locations to determine the G x E interactions. The experimental designs were complete randomised blocks with four replications. Eight morphological and agronomic characters studied were subjected to an ANOVA and significant differences were found for some traits between cultivars tested in the glasshouse. Significant differences also occurred among replications for some traits in both trials. There were not many morphological differences between cultivars and therefore it is difficult to identify individual cultivars merely by morphological characters. · Seeds of eight cultivars were used to determine the oil content and fatty acid composition of the seed oil. The percentage oil was relatively high for all cultivars; however, there was not much difference between cultivars for oil content. The percentages of each fatty acid varied greatly among different cultivars and therefore there is a potential for genetic improvement in oil quality. · AFLP analysis was used fingerprint commercial cultivars and three wild type varieties. Six primer combinations between EcoR I and Mse I were used to determine genetic relationships. A total of 406 fragments were generated, of which 229 (56.4%) were polymorphic. A low level of genetic diversity was detected in kenaf genotypes. · Separate and combined analyses of variance across locations, three types of stability parameters and correlation analyses were performed. · The separate trial analyses for two locations have shown significant differences among cultivars for three yield traits. With the exception of plant length, there were no significant differences between replications. The combined analysis of variance across locations showed highly significant differences among locations for three yield traits. There were, however, no significant differences among genotypes and their interactions with localities for three traits. All cultivars performed on average better in location 1 (under irrigated conditions) for six measured traits. According to Wrickeâs (1962) ecovalence, El Salvador, Everglades 41, and SF 459 were the most stable cultivars for the three yield traits respectively. Lin and Binnsâ (1988) cultivar superiority measure indicated that El Salvador and Tainung 2 were the most stable cultivars for the three traits. Nassar and Huehnâs (1987) non-parametric measure of stability revealed that El Salvador and SF 459 had the smallest changes in ranks and thus were the most stable cultivars.