The effect of covariate of alternate bearing in adaptation studies in olive (Olea europaea L.)

In order to confirm the existence of interactions in quantitative terms, the most obvious method is to participate in the results of each year in combined analysis. In the meantime, horticultural products are affected by the influence of the inner (not the year) of the plant, and their alternate bearing from year to year, low or high. In this research, in order to eliminate this effect and Adjusting the mean of the years, the alternate bearing index of each genotype is used as auxiliary variable in the model in order to determine the changes of each component of combined analysis and finally, using stability parameters, varieties and genotypes compatible with The environmental conditions of this climate are introduced.

For this research, 100 genotypes and cultivars collected from all over Iran were used. These genotypes and cultivars were planted in a completely randomized block design (RCBD) with three replications at Olive Tarom Research Station and estimated yield of each tree in kg per tree for 6 years from 2011 to 2016. The Alternate bearing effect was deduced from the data by calculating the ABI for each genotype during successive two-year periods and correcting the averages using it. Finally, the data were analyzed and combined in two main and corrected formulas, and finally from Ten stability parameters were used to identify a stable cultivar in year.

The results of combined analysis of variance for different methods had a significant difference. So that the genetic component of the combined analysis table increased 61 percent in the corrected data compared to the original data. Also, the effect of the year of this table was dramatically justified from 37 to 14 percent, down 23 percent. The amount of interaction in both cases for corrected and non-corrected data was significant with 35% and 32%, respectively. The comparisons performed for the pair of corresponding years using the t-student test indicated the difference in mean performance for both the same year for the original and corrected data. The value of this parameter was calculated positively and negatively in succession. Which shows that the effect of interacting the auxiliary variable is the alternate bearing index in the calculations. The absolute value of this parameter represents more exposure genotypes or varieties of the phenomenon of alternate bearing. The most stable cultivars in this study with desirable function and using the data correction method, Koroneiki and Conservalia cultivars, were determined according to three factors of stability in yield, yield and oil quality.

The existence of an alternate bearing in horticultural products can significantly alter the results of compatibility studies in these products. The internal phenomenon, which does not depend on the year and its parameters, changes the actual suitability of the genotypes and the numbers of participants in the experiment. Intervening the alternate bearing index in compatibility analysis as an auxiliary variable is an important factor in reducing the effects of alternate bearing in calculations, adjusting the meanings of each genotype environment, and ultimately making the correct decision to reject or accept the adaptation of a genotype. This difference in the overall survey and determining the compatibility of cultivars is obvious in the two corrected and main data sets. On the other hand, consideration of the amount of yield, in addition to stability, is essential in determining the optimal cultivar.