MSc

The present study entitled “Standardization of hybrid rice seed production for
Kerala using three line system of breeding” was carried out in the College of
Agriculture, Vellayani and Integrated farming system research station (IFSRS),
Karamana during 2019-2020, with an objective to standardize GA3 and
brassinosteroid and to optimize the planting ratio in restorer line (R line) and male
sterile line (A line) to get maximum hybrid seed yield under Kerala condition. The
study comprised of two experiments, the phenological studies in male sterile line
(Aline) and standardization of GA3 and brassinosteroid dose for the planting ratio of
A, R line in 6:2 and 8:2.
Phenological studies of the CMS line CRMS31A were taken under protected
condition during different growth stages. The production of tillers on male sterile line
started at 23.3 days after sowing. At maturity, the plant height reached up to 123.33
cm length with 18.1 total numbers of tillers. The sterile plant produced total of 91
leaves and the flag leaf had 39.01 cm2 area. The initiation of the panicle was observed
on 58.9 days old plants and panicles were developed between internodes of the first
stem. The panicle initiation was associated with the beginning of stem internodes
formation and the initiated panicle was microscopic in size (2-4 mm) with a fuzzed tip
inside the main culm. The increase in size of the panicle primordia and its upward
extension inside the leaf sheath were detected inside the rapidly elongated culm. The
booting stage was started at an age of 67.2 days then the first panicle was emerged on
74.1 days old plant and fifty percentages of panicles were emerged within a week.
Flag leaf angle play a vital role in the percentage of seed filling (fertility percentage)
by acting as a barrier between pollen from the male parent and the CMS plants
spikelets. The average flag leaf angle of CRMS 31 A was 15.60 which was very less
when compared to traditional varieties. The CRMS 31 A had taken 85.5 days to
anthesis and taken 9 days to finish the anthesis of whole spikelets on panicle.
In the second experiment, field evaluation of hybrid seed production in the
cross between CRMS 31A and the identified restorer „Remya‟ was done in the fields
of IFSRS Karamana for standardising the planting ratio and the doze of growth
hormones. This experiment was laid out in Randomized Block Design (RBD) with
three replication during March-July 2020 (Virippu). The parental lines were sown in
staggered dates according to the duration of the CMS line and the pollen Restorer
line. The sowing of male and female parents were planned to achieve the
synchronization in flowering. The R line was sown in three staggered dates. i.e., one
at three days before the sowing date of CMS lines, the second set along with CMS
line and the third set were sown three days after the sowing of CMS lines. The sterile
R line and pollen parent were sown in the planting raio of 6:2 and 8:2 and two doses
of GA3 (50 and 70 ppm) and brassinosteroid (2 and 6ppm) were sprayed at 15-20%
heading and 35-40% panicle emergence. Observations on eight morphological and
five yield traits were recorded during the crop production.
All the traits used in the study showed significant variations. The mean
performance of CRMS 31 A observed better performance in morphological and yield
parameters at 70 ppm GA3. The treatment T5 (GA3-70 ppm, BRs-2ppm with 6:2
planting ratio) recorded the highest panicle exsertion (8.707 cm), plant height
(145.653 cm) and flag leaf area (64.747 cm2) followed by T6 (GA3-70 ppm, BRs-
2ppm with 8:2 planting ratio). The highest productive tiller (25.00), total tiller (27.00),
number of leaves (135.00) and leaf angle (26.600º) were observed in T6 (GA3-70 ppm,
BRs-2ppm with 8:2 planting ratio) and followed by T5. The higher concentration of
BRs reduced the flag leaf area (42.767) in T3 (GA3-50 ppm, BRs-6ppm with 6:2
planting ratio). The morphological traits of the male sterile line was improved with
respect to panicle exsertion, flag leaf area, productive tillers and leaf area index by the
application of GA3 70ppm and BRs 2ppm.
The 1000 grain weight was higher in T3 (19.400g) followed by T5 (17.267g)
and T6 (16.500g) and the least was in control treatment T4 (13.733g) and T7 (13.900g).
The highest number of filled grain per panicle (33.00 nos) and lowest number of
unfilled grains per panicle (17 nos) were observed in T5 with 70ppm GA3. The highest
number of unfilled grains per panicle was found in control plants (T4 and T7). The
Spikelet fertility percentage was more in T5 (19.507%), followed by T3 (16.140%) and
less fertility percentage was observed in control plants T4 (7.127%) and T7 (7.397%).
Highest seed yield per plot was recorded in T6 (1489.320g) followed by T5
(1355.746g) lowest seed yield was observed in control plants T4 and T7.
The drawback of CMS line could be minimized by the application of
hormones and improve seed set can be obtained. Humidity and the wind velocity
prevailing in the location was not favorable for free flow of pollen and better seed set.
So a more favorable season has to be tested for better yield.
In this study the doze of Brassino steroids 2ppm and GA 70 ppm in both planting
ratios of 6:2 and 8:2 had given substantially higher yield over the control. So hybrid
rice seed production in Kerala can be enhanced by spraying of GA3 70ppm and
brassinosteroid 2ppm at 15-20% heading of tillers and 35-40% panicle emergence.
The row ratio of the female parent to the restorer parent can be 8:2 considering the
increased seed yield realized. More seasons and locations have to be tested to identify
the best season and location for hybrid rice seed production in Kerala.