Genetical studies of quantitative characters in peas. 1. A seven-parent diallel cross of cultivars

Abstract

l . Results from the F 2 generation of a set of half diallel crosses involving seven pea cultivars are discussed with reference to a number of plant characters likely to be of commercial interest . These characters are days to and node of first flower, mean internode length, number of flowers per node and number of ovules per pod.2 . An outline is given of a series of analytical steps to which the data for each character were subjected . 3 . All characters were found to be under genetic control ; a polygenic system in the case of four of the characters, the fifth, mean internode length, being additionally controlled by a major gene, In general, the genetic system was of an additive nature, dominance and interaction being of minor importance . 4 . The policy of the majority of pea breeders has been to intercross the most desirable cultivars and as far as the seven parents used in those experiments are concerned, this will continue to be the right policy .

Analysis of a 5-parent half diallel in dried pea (Pisum sativum L). I. Seed yield heterosis

“…This result is in contrast to those generally reported on this subject (Krarup and Davies, 1970;Snoad and Arthur, 1973;Srivasta et al, 1986; Singh and Singh, 1987). Gritton (1975), from an 8-parent full diallel analysis, found significant SCA effects for yield accounting for 17-51% of the total combining ability variance depending on year and location.…”

“…Heterosis for yield components was significant only for the number of pods/plant and the number of sseds/pod on the branches, but not for the number of seeds/pod on the whole plant or for dry weight/seed. (Krarup and Davies, 1970; Snoad and Arthur, 1973;Srivastava et al, 1986;Singh and Singh, 1987). These results supported the view that the appropriate breeding approach is the development of pure lines on the basis of the parents used in each study.…”

Genetical studies of quantitative characters in peas. 2. A six-parent diallel cross of cultivars and primitive forms

“…The characters with which it proved possible to complete the series of analytical steps outlined by SNOAD & ARTHUR (1973) will be taken and discussed individually .…”

“…Records were kept of as many characters as possible and the data were then subjected to the series of analytical steps outlined in an earlier paper (SNOAD & ARTHUR, 1973) ; these analytical steps are based upon the work of JINKS (1954) and HAYMAN (1954) which is reviewed by MATHER & JINKS (1971) . The main difference between the analysis of these data and that published earlier was that a full set of diallel crosses was available in the present experiments so that reciprocal differences could also be recognised .…”

“…During the past eight years a number of sets of diallel crosses have been analysed in peas (ROWLANDS, 1964 ;WATTS, STEVENSON & CRAMPTON, 1970 ;KRARUP & DAVIS, 1970 ;SNOAD & ARTHUR, 1973) . In all these experiments the parents used were European and North American cultivars and, generally speaking, there was a fair measure of agreement regarding the systems of genetic control that were revealed .…”