Assessment of variability, correlation and response to selection in four cultivars of sweet potato "Ipomia batata, L." under alexandria environmental condition

الملخص EN

The efficiency of two cycles of clonal selection on some economical characters in four different varieties of sweet
potato (Abbies, Mabrouka, Beaurogard and local Nigerian variety) were studied.

The magnitude of variability,
heritability and response to selection, as well as phenotypic correlation coefficients among all possible pairs of the
studied characters were measured.

This work was carried out at the Experimental Station Farm (at Abies), Faculty of
Agriculture, Alex.

Univ.

, Alex.

Governorate, Egypt during three summer seasons of 2016 - 2018.

The obtained results
illustrated generally that the estimated coefficients of variability and ranges of the studied characters of the four cultivars
original populations reflected high and enough variability, which suggested high possibilities of conducting successful
and efficient selection.

This lead to produce improved cultivar with better performance than its original population.

Also,
the results demonstrated, in general, that two cycles of clonal selection exhibited high efficiency for improving all
studied characters with different rates, compared with the original population.

The estimated values of heritability (h2
bs)
for the various studied characters were found to be high for dry matter and very low for root diameter.

The highest
estimates of genetic advance as percentage of mean were obtained for root number-1 plant 99.7% , root weight plant-1 89.0
% , root length 77% and vine length 69.2% .

The results also, revealed that phenotypic clonal selection was ended up with
populations that have improved root number plant-1 for Abbies, Mabrouka and beaurogard by 77.87 % , 101.9% and
51.71% , respectively, in respect to the original population.

The increment over original population for fruit number plant-
1 in Nigerian variety was observed in C1 population which reached 53% .

Meanwhile, the results also demonstrated that
Abbies produced the maximum number of tubers plant-1 (5.87 tubers) and the highest root weight plant-1 was observed in
Beaurogard (1.67 kg/ plant).

Moreover, Abbies variety had the highest values for dry matter, TSS and carotene content
and it was statistically different from the remaining three sweet potato varieties.

Furthermore, correlation estimates
revealed significant associations among the various pairs of the studied characters.

These findings appeared to be
desirable for achieving the objectives of the selection in the present study.

Accordingly, improving roots yield and its
components of sweet potato can be achieved through purification of the most important and commercial cultivars to
produce improved clones through clonal selection program.