Pheno-morphological traits of diverse Brassica juncea (L.) genotypes determining variability in Lipaphis erysimi (Kaltenbach) population build-up

Abstract

Role of Brassica juncea pheno-morphological variation in imparting resistance to Lipaphis erysimi was studied. There
was significant variation for most phenotypic and yield attributing traits, and aphid resistance indices on the test
genotypes, across seasons, and for genotype × season interactions. Genotype RBJ 49 with longer siliquae, greater
number of siliquae and seeds per siliqua was found with moderate aphid resistance. Taller genotypes PDZ 6 and RBJ 11
with small siliquae although took longer time to flower and mature, aphid resistance indices were lower than on other
genotypes. Genotype IC 355399 having bunchy inflorescence, dark yellow flowers and higher siliquae, harboured
greater aphids, while GP 454 and RP 11-2-1-3-1 having cream colour petals displayed opposite reaction towards aphids.
In spite of significant variability in test genotypes for seedling colour, petal colour and siliquae orientation, their
regression coefficients were nonsignificant with number of aphids and aphid resistance indices. However, path coefficient
analysis revealed that number of aphids, aphid population and damage indices, point to first branch and siliqua, seeds
per siliqua, total siliquae and siliquae length have significant association with aphid resistance index, indicating that
these traits directly or indirectly contribute to differential reaction against L. erysimi in B. juncea.