MSc

The present study entitled “Genetic evaluation of F2 generation for yield
and water stress tolerance in upland rice” was carried out in the Department of
Plant Breeding and Genetics, College of Agriculture, Vellayani during 2016-2018.
The objective was to evaluate the pattern of variability in F2 for yield and yield
contributing traits under upland and drought situations and to select superior
segregants combining drought tolerance and high yield. The study material
included four parents and three F2 populations selected from the Ph.D project
entitled “Genetic analysis of drought tolerance in rice (Oryza sativa L.)”.
The study comprised of two experiments .In experiment- I,
the parents
and F2 segregants were raised under rainfed upland condition exposed to natural
stress. Among the F2 populations, Vaishak x Harsha (T6) recorded the highest
mean grain yield plantˉ1 (38.45g – 48.15g) and lowest mean spikelet sterility
(7.76%-21.18%). T6 recorded the highest mean values for number of productive
tillers plantˉ1 (9 - 16) and leaf area index (mean: 1.67). Vaishak x Vyttila 6 (T5)
recorded the highest mean values for number of spikelets panicleˉ1 (149 - 178),
harvest index (44.88% – 48.15%) and proline content (mean: 0.29mg g−1).
Thottacheera
x
Harsha
(T7)
recorded
the
highest
mean
values
for
chlorophyll(mean: 1.78mg g−1) and leaf soluble protein content (mean: 9.36mg
g−1). The data obtained was subjected to transgressive segregation analysis and in
T5 more than 50 percent positive segregants were observed for number of
productive tillers plantˉ1, spikelet sterility, number of spikelets panicleˉ1 and
panicle length. T6 recorded high percentage of positive segregants for number of
productive tillersˉ1, grain yield plantˉ1, plant height and spikelet sterility. In T7
percentage of positive segregants were the highest for spikelet sterility and
number of productive tillers plantˉ1. Dendrogram drawn on the basis of squared
Euclidean distances classified the genotypes into four clusters. Cluster I -T1,T5,T6,
cluster II- T4, cluster III -T2,T7 and cluster IV-T3.
In experiment II, another set of parents and F2 segregants were grown
under rainshelter imposing reproductive stage moisture stress. Irrigation was
given at 20mm depth once in seven days from panicle initiation stage onwards.
Among the F2 segregants, T5 recorded the highest mean values for grain yield
plantˉ1 (11.80g – 18.88g), number of spikelets panicleˉ1 (128 - 174), grain weight
panicleˉ1 (2.60g – 4.33g ), harvest index (42.44 % - 68.13%) and proline content
(mean: 0.57) and the lowest for spikelet sterility (5.50% - 22.27%). T6 recorded
the highest mean value for panicle length (19.60cm – 27.50cm). T7 marked the
highest mean values for number of productive tillers plantˉ1 (3 – 7), chlorophyll
(mean: 1.28mg g−1) and leaf soluble protein content(mean: 8.82mg g−1) and leaf
area index (mean: 0.71). In T5, more than 50 percent of positive segregants were
recorded for grain weight panicleˉ1, number of filled grains panicleˉ1 and number
of spikelets panicleˉ1. T6 recorded higher percentage of positive segregants for
straw yield plantˉ1 whereas T7 recorded the highest positive segregants for 1000
grain weight. On the basis of dendrogram drawn the genotypes were grouped into
four clusters. Cluster I -T4 and T6, cluster II-T2,T7, cluster III - T3, T5 and cluster
IV - T1.
Among the F2 segregants, Vaishak x Harsha (T6) performed well under
upland condition whereas Vaishak x Vyttila 6 (T5) performed well under stress.
The high yielding variety Vaishak released for uplands might have transferred its
superior yield characters to the progeny. The transgressive segregants with
favourable traits thus obtained can be effectively utilised for selecting superior
genotypes combining drought tolerance and high yield.