INHERITANCE OF GROWTH RATE AND NODE DEVELOPMENT IN A DIALLEL CROSS OF PEAS AND CORRELATIONS WITH OTHER TRAITS

8 PNL Volume 16 1984

RESEARCH REPORTS

INHERITANCE OF GROWTH RATE AND NODE DEVELOPMENT IN A DIALLEL CROSS OF

PEAS AND CORRELATIONS WITH OTHER TRAITS

Csizmadia, L. Research Station of Vegetable Crops Research Institute

Ujmajor, Hungary

The vigorous early growth of plants is one of the prerequisites of

a high pea yield, inasmuch as vigorous plants are better able to

withstand many of the problems which commonly occur in the Middle

European climate, e.g. drought, heat and leaf weevil. Although environ-

mental and cultural conditions are important factors influencing

seedling establishment, smooth-seeded peas usually show more rapid early

growth than wrinkled-seeded types. There are, however, considerable

differences among the wrinkled-seeded varieties themselves.

To study the inheritance of growth rate and node development in the

first three weeks following emergence, six wrinkled-seeded varieties

('Skinado', 'Green Arrow', 'Jof', 'Puget', 'Wav. 18045' and 'Rapid')

and their F1 hybrids ( without reciprocals) were evaluated. Four plants

of each parent or hybrid were grown in a 25-cm container replicated 3

times in a randomized block design. The experiment was carried out in a

growth room under the following conditions: 23/18C day/night tempera-

tures, a 16 hr photoperiod and at least 60% relative humidity. Shoot

extension per week, node development (number of days required for the

full development of a node), plant height at flowering, days to first

flower, and first flowering node were determined. The statistical

analysis of data was done by Griffing's Method 2, Mode] 11.

Only the specific combining ability (SCA) variance component was

significant for rate of growth, indicating that non-additive effects are

important for this trait (Table 1). In accordance with the insig-

nificant s²_g, the narrow sense heritability value was low. Both GCA and

SCA variance components were significant for node development and they

were nearly of the same magnitude. The narrow sense heritability value

(52.8) suggests that progress in node development could be achieved by

breeding procedures that are able to increase the frequency of those

genes that are primarily additive.

PNL Volume 16 1984

RESEARCH REPORTS

Table 2. Phenotyplc and genotyplc correlations in parental and F1

generations.

Most of the significant phenotypic correlations (r_p) had negative

signs (Table 2). The association was stronger in the parental popula-

tion except rate of growth vs days to first flower. More rapid node

development was associated with late flowering, flowering at higher

nodes and taller plants. The behavior of rate of growth was different:

an increased rate of growth was associated with early flowering. The

associations noted in the rp values were indicated again in the similar

genotypic correlation coefficients (r_g ).