EFFECT OF YEAR AND SPACING ON COMBINING ABILITY IN PEA

PNL Volume 18 1986 RESEARCH REPORTS

Csizmadia, L.

Research Station of Vegetable Crops Research Institute

Ujmajor, Hungary

Estimates of general and specific combining ability effects and

variances are generally obtained from space planted experiments and in most

cases are not repeated over years or locations. Little is known of the

extent of different genotype x environment interactions and Co what extent

they affect the general (GCA) and specific combining ability (SCA)

variances. The present investigation was undertaken to provide information

on these aspects.

Ten pea varieties and lines (RS-455, Br-52, 'Jof', 'Puget'

'Multipod', 'Extra Rapide ' , Wav. 01, 'Skinado', Wav. 180045, FJ-111) were

crossed in all possible combinations, excluding reciprocals. Parents and

F1 progenies were evaluated in two years in space planted experiments

(single row plots, rows spaced 1 m apart, 20 cm plant-to-plant spacing),

parents, and F2 progenies in one year in a wide (as in F1 ) and in a narrow

spaced experiment (4-row plots, rows spaced 15 cm apart with 10 cm plant-

to-plant spacing). Each experiment was arranged in a randomized block

design with three replications. Plot means were subjected to analysis of

variance and significant interaction variances were analyzed following

Griffing's method II (both fixed and random effects models were studied) as

detailed by Singh (1).

Analysis of variance for combining ability showed that the mean

squares due to GCA, SCA, year effect (in F1), and spacing effect (in F2)

were highly significant for all traits. GCA x year and GCA x spacing

components of interaction variances were significant for all characters

except for seeds per 5 pods. SCA x year was significant only for pods per

plant and SCA x spacing only for seeds per 5 pods (Table 1).

Estimates of various genetic parameters and heritabi1ities are shown

in Table 2. In accordance with the data of Table 1, estimates of s²_g and H_n

were higher for seeds per 5 pods and 100 seed weight both in F1 and F2.

Due to space limitations, estimates of various effects are not

presented here, only correlations between GCA; means of parents and CCA x L

are recorded in Table 3. There are significant correlations between GCA

vs. means of parents (both in F₁ and F₂) GCA in F₁ vs. GCA in F₂ for each

character. In spite of the significant interactions estimates of general

combining ability seem unbiased.

1. Singh, D. 1973. Indian J. Genet. 33:469-481