Indian Society of Genetics & Plant Breeding


Comparison of efficiency of F1 and F2 generations in identifying potential inbreds for improvement of a reference maize hybrid

Published on Jul 30, 2018 04:20 AM

The estimators namely, the relative frequency of favourable
dominant alleles in a donor inbred (/lG), the net
improvement (NI) and the probability of net gain of
favourable dominant alleles (PNGg) were compared for
their efficiency in ranking donors both within and between
two methods, one using inbred and F, data and the other
using inbred and F2 data. Six donor maize inbreds (TCA21,
TCA22, TCA24, CML32, IPA40 and SC7) were crossed to
each of the parents of a reference maize hybrid, IPA2
x IPA34. Thirteen F,'s, 13 F2's and 8 inbreds were evaluated
in two locations in 1996 for grain yield. Inbreds with the
highest and the lowest estimates of /lG, NI and PNG
were the same in both the methods. The efficiency of
different estimators in identifying donors was highly
consistent within a method and comparison of efficiency
among them did not change with the method used. The
ranking of donors as per /lG and PNG
g varied greatly,
while that as per NI remained the same with the method
used. The donors with the closest relative relationship to
either parent of the reference hybrid were the same in
both the data sets. The differences in ranking of donors,
different assessments of relative relationships of lines
and different decisions on where to backcross prior to
selfing may have stemmed from failure of assumptions
such as no epistasis or difference in precision in the
evaluation of different generations. The study indicated
that direct selfing of the crosses IPA2 x TCA22 and IPA34
x SC7 would release an improved version of IPA2 and
IPA34, respectively in a relatively shorter period.

Keywords: Zea mays, donor, favourable alleles, relative relationship, backcross


Year: 2002
Volume: 62
Issue: 1
Article DOI: NA
Print ISSN: 0019-5200
Online ISSN: 0975-6906


N. Sarma Barua and B. K. MUkherjee info_circle
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