Abstract:
A comprehensive understanding of Genotype X Environment interactions (G X E) and
yield stability facilitate cultivar recommendation across diverse environments. The
objective of the present investigation was to study G X E interaction and yield stability
of tea. Fifteen TR I4000 series tea cultivars were tested for cycle yields in a randomized
complete block design with three replicates, in three agro climatic regions in Sri Lanka.
A combined analysis of variance revealed significant differences between genotypes
and environments where they were tested. Furthermore a substantial amount of
significant G X E interaction for tea yield was detected in the tested genotypes. Five
parametric stability statistics viz Finlay and Wilkinson regression coefficient (b),
Eberhart and Russell parameters, environmental variance (S2j), Shukla’s stability
variance (c^i) and Lin and Binns Superiority Index (PI) were used to study the stability
of genotypes. Certain genotypes exhibited stability for some type of measures and
instability for others, making it difficult to reconcile these assessments in to a unified
conclusion. Hence, the level of association among the stability parameters was assessed
subsequently using SpearmanDs rank^correltion. Cultivar mean yield was correlated
significantly and positively with Superiority Index (i=0.914) whereas it was negatively
correlated with environmental variance (r=0.825) indicating that these parameters could
be used for simultaneous selection for yield and stability. Regression coefficient and
Eberhart and Russell parameters showed positive correlation (r=0.992) indicating that
any of these parameters could be used to study G X E interaction in tea. The principal
components analysis was performed for the ranks of genotypes obtained from different
stability parameters to assign genotypes in to groups that correspond with different
stability statistics. The first two principal components (PC) accounted for 97% of the
total variability enable grouping of genotypes in to four distinct classes and those
groups provide useful information for identification of high yielding stable genotypes
for better commercial exploitation.
