GENETIC-VARIABILITY, HERITABILITIES AND CORRELATIONS OF 15 CHARACTERS IN A JERUSALEM-ARTICHOKE CLONE POPULATION (HELIANTHUS-TUBEROSUS L)

Fifteen developmental and yield component characters were recorded from 16 different Jerusalem Artichoke clones, sampled among a large clone collection. The clone differences were highly significant, showing a wide range of variation in respect of all characters under study (table I). Broad sense heritability estimates ranged between 19.5 and 96.1%. They were very low for yield related characters and very high for tuber dry matter content and developmental characters. Expected genetic advance with selection of the highest 5%, expressed as the percentage of the mean, varied from 9.5 for emerging time to 30.7 for stalk height (table II). Path analysis was used to partition the genetic correlations between 5 characters into direct and indirect effects. Whole plant dry matter had high positive direct and indirect effects on tuber dry matter yield (tables IV and V). The mean clone effects for the 15 characters were submitted to a principal component analysis. The first 4 components explained 90% of the total variation. The dispersion of clones along the first principal component showed the existence of 2 separate morphologic clusters: early clones (a limited number) and late clones (table VI, fig 1). Genetic and environmental correlations between characters were evaluated (table III). Tuber dry matter yield had high positive genetic correlations with fresh tuber weight, whole plant dry matter, green leaf duration and flowering time. Flowering time appeared to be the most efficient character to be associated in a selection for the improvement of tuber yield. However the possibilities for increasing tuber yield by selecting for a later flowering time appeared limited and uncertain.