Agriculture Reference
In-Depth Information
symptoms of chilling injury such as chlorosis, necrosis or
growth retardation. In contrast, chilling tolerant species are
able to grow at such cold temperatures.
Conventional breeding methods have met with limited
success in improving the cold tolerance of important crop plants
involving inter-specifi c and inter-generic hybridization.
According to previous research, cold tolerance is controlled
by many different genes. The mechanism of how these
genes control cold tolerance is still not clear. Importance of
cold tolerance by conventional breeding techniques is very
diffi cult and time consuming. It requires expensive facilities
for screening and it takes many breeding techniques to bring
together all the important agronomic, physiological and quality
traits. The solution would be marker assisted breeding, but fi rst
a better understanding of the molecular basis of cold tolerance
is required.
In Chile there was breeding of 12 parents into the previously
developed local population PQUI-I that segregates for a
recessive male sterile gene, the parents are from different
origins and represent a broad genetic base. Individual crosses
were made between each parent and male sterile plants of
PQUI-1. The F
1
seeds of each individual cross were mixed in
different proportions and sown in Chile. F
2
seeds were sent
to the International Centre for Tropical Agriculture (CIAT) in
Colombia, for recombination, by harvesting seeds produced on
the male sterile plants. Seeds from the fi rst recombination were
sent back to Chile for second recombination. The population
PQUI-2, with broad genetic base represents a new starting point
for temperate climate rice improvement through recurrent
selection breeding and opens possibilities to breeders in the
near future to use it as segregating population to derive and
