Varieties By Environment Interaction And Its Effect On Zoning Egyptian Cotton:

Ibrahim Sayed Mohamed Hassan

SUMMARY AND CONCLUSIONCotton in Egypt ranked first in relation to fiber crops and efforts are exerted toincrease cotton production and quality through agricultural policies and breeding newvarieties.It is well known that the productivity of any variety is the outcome of theinteraction between the genetical constitution and environmental conditions. For thisreason, cotton should be grown under suitable environmental conditions to achievethe highest yield and the best quality.Therefore, 30 field experiments were conducted during the three successiveseasons 1992 , 1993 and 1994 at ten different regions :-- Upper Egypt (Sohag, Assuit, El-Minia and EI-Faiyum).- Southern and Middle Delta (Dakahlia, EI-Gharbia and sharkeih.- Northern Delta (Kafer El-Sheikh, El-Beheira and Damaitta), to evaluate 15cotton genotypes of which twelve are the commercial varieties namely, dendera, Giza45, Giza70, Giza 75, Giza76, Giza 77, Giza 80”Giza 81, Giza 83, Giza 84, Giza 85and Giza 86, in addition to the three promising strains (Giza 75 x Rus. 6022), (Giza77 x Giza 45A ) and (Giza 77 x Giza 45B) .Varieties and strains all together were grown following the routine adapted in theexperimental stations. A complete randomized blocks design with four replications ineach of the 30 environments (combination of ten locations in three years).Variance components and different stability estimates over location and years werecalculated for seed cotton yield and yield components, in addition to fiber propertytraits.The resuhs obtained could be summarized as follows :-I . mod: or mttgn IUOtxDg.1gqtjsm •• yem aDd the iDtcgctjOD’ bctpwplb. ;-I .1. Effect of cotton variety :-I • 1. A • Varietal effect on the yield and yield components :-Results obtained revealed that yield and yield component characters werehighly significantlyaffected by cotton variety.1- Mean seed and lint cotton yields showed that Giza 85 and the promising strainGiza 75 x Rus. 6022 had the highest values, while Giza 45 gave the lowestyields.2- Regarding boll weight and seed index, Giza 75 and Giza 85 gave the highestvalues for these traits, while Giza 80 and Giza 83 had the highest values for lintpercentage and lint index. On the other hand, Giza 45 and the promising strainGiza 77 x Giza 45A had the lowest values for lint percentage and lint index.L 1. B. Varietal effect on the fiber properties :-The results demonstrated that all the studied fiber properties were significantlyaffected by variety .Mean values of the micronaire reading were lowest for Giza 45 and Giza 77 xGiza 45A.As for fiber strength and fiber length, it was clear that Giza 70, Giza 45 andGiza 77 x Giza 45B had the highest values.L 2 • Effect of the years :-L 2 : A Seasonal effect on the yield and yield components :-Results revealed that the climatic conditions during the second year (1993)affected favorably all characters under study in comparison with the other twoyears of 1992 and 1993. The differences among the three years weresignificant for all characters, except number of bolls per plant and lintpercentage .L 2. B. Seasonal effect on the fiber properties :-Results revealed that the climatic conditions during the second year (1993)were more favomable than those in the other two years (1992 and 1994) inaffecting the two characters micronaire reading and 50 %span length only.The differences were significant among the three years in all characters, exceptfiber strength trait.L3. Effect of the location :-I .J. • A • location effect on the yield and yield components :-The ten locations differed significantly concerning seed cotton yield, lint yieldand lint percentage. EI-Faiyum governorate favourably affected seed cottonyield, lint yield, boll weight, number of bolls per plant and seed index ascompared with the other locations. While, El-Beheira was better than EIFaiyumfor lint index trait. El-Dakahlia governorate favourably affected lintpercentage. On the other hand, El-Minia and Assuit governorates were lowerthan other locations tested in all characters studied.I • 3, • B • location effect on the fiber properties :-The ten location differed significantly concerning fiber properties, except themicronaire reading. EI-Faiyum and Sohag governorates favourably affectedfiber strength and fiber length (2.5 % and 50 % span length) and recorded thehighest values as compared with the other locations, while the lowest valueswere observed in El-Mioia and Sharkeih locations.L 4 • Effect of the interaction between cotton varieties and yean :-Significant interaction effects were detected for seed and lint cotton yields,number of boDs per plant, lint percentage, lint index, seed index and all fiberproperty traits under study.These results give evidence that the varieties differed in their responses to theenvironmental conditions from one year to another.This means that the superiority of a certain variety depends on the conditionsprevailing dwing the growing season.I • 5 • Effect of the interaction between cotton varieties and locations r-Significant effects for genotype x location were found except, with boll weightand lint index which were not significantly affected with this interaction.1. from the resuhs of seed and lint cotton yields, it is apparent that for producingthe highest seed and lint cotton yields, it is recommendable to grow Gina 80variety at Upper Egypt (Sohag and Assuit), Gina 85 and Gina 83 at MiddleEgypt (El-Minia and El-Faiyum), the promising strain Giza 75 x Rus. 6022 atSouth and Middle Delta (El-Gharbia and EI-Sharkeih) and to grow Giza 83,Gina 86 and Giza 75 x Rus. 6022 genotypes to get the highest yield at NorthDeha (Dakahlia, Damiatta, EI-Beheira and Kafer EI-Sheikh).2. High mean seed cotton yield and yield components exhibited by the long staplegenotypes are due to their genetic constitution in addition to their highadaptability for wide environmental conditions at several locations and it couldbe recommended that they are to be included in the breeding programs aimingto improve yield and its components. On the other hand, the extra-long staplegenotypes were less adapted for wide environmental conditions thus, thesegenotypes have to be grown in the North Delta regions as the environmentconditions are more suitable for producing the best fiber properties, becauseExtra-long staple genotypes produce higher fiber strength and longest fiberlength than the long-staple ones, mainly due to genetic differences betweenthemI • 6. Effect of the interaction between locations and years :_This interaction had highly significant effect on all yield and its componentsand fiber properties traits under study.from the resuhs of the interaction between location and years, it could be seenthat the different traits changed in these means from location to another andfrom year to another, but generally it can be seen that Sobag in 1992 was thebest environment for fiber properties, while EI-Faiyum at the same year gavethe best yield.I • 7 • Effect of the interaction between cotton varieties. locations and years:-This second order interaction affected significantly all traits of yield and itscomponents. The effect was highly significant for all fiber property traitsexcept, fiber length (2.5 % and 50 % span length), which were insignificantlyaffected.The results show the important role of each of (genotypes, locations, years,locations x years interaction, as well as genotypes x environment interaction)that affect seed cotton yield and yield components and also fiber propertytraits ..Therefore, it seems necessary to continue evaluating cotton genotypes, old ornewly produced, by growing them at several locations over an adequatenumber of years before recommending any variety for a certain location.n.Varian” component’ and beritabjlilv :_I . High heritability values were reached for seed cotton and lint cotton yields,being 89.55 % and 94.05 %, respectively.2 High heritability values of95.71 %.85.58 %. 99.22 %.99.06 % and 93.92 %were also reached for boll weight, number of bolls per plant, lint percentage,lint index and seed index traits, respectively.3 There was an essential amount of genetic variance for each trait hence, thebroad sense heritabilty estimates were high for all traits. Genetic coefficient ofvariability ranged from 4.37 % for seed index to 17.28 % for lint yield, thesevalues indicated the environmental effects on all traits studied.4 The high heritability values for fiber properties were 97.89 %. 97.82 %,99.26 %and 97.84 %for micronaire reading, fiber strength, 2.5 % span lengthand 50 % span length, respectively.5 . Genetic coefficient of variability ranged from 5.24 % (for 50 % span length) to8.92 % (for micronaire reading). These values indicated that environmenteffects on all traits studied were considerable.m • r...enptynje; ’tahUin for djffercut &CU0types :-1. Adaptability estimates indicated that Giza 45, Giza 76, Giza 70, Giza 77 andGiza 77 x Giza 45A which yielded below average mean yield overenvironments are poorly adapted to all environments. However, the genotypesGiza 75 x Rus. 6022, Giza 85, Giza 83, Giza 86, Giza 75, Giza 84 and Giza 80which were above average mean yielding ability had general adaptability orwell adapted to all environments. The remaining genotypes (Dendera, Giza 81and the promising strain Giza 77 x Giza 45B) which were not significantlydifferent from the average mean performance of all cultivars had averagestability.2 - The several stability estimates used, indicated that for selection for stability withthe objective of incorporating this important trait in the Egyptian cottongermplasm, the following genotypes may be considered as breeding stocks forspecific traits :-Seed cotton yieldLint cotton yieldBoll weight and seed indexNumber of opening bolls per plantLint percentageLint indexGiza 75 x Rus. 6022.Giza 84.Giza 80 and Giza 86.Giza 86.Giza 86 , Giza 81 , Giza 77.and Giza 77 x Giza 45B.Giza 86 and Giza 85.3- Only extra-long staple met the performance response and stability characteristicsof ideal genotypes for all fiber property measurements. Therefore, the extralongstaple genotypes may be used as a breeding stock for incorporating in anycrosses with the objective for selection for stable :fiber properties (micronairereading, :fiber strength and :fiber length).