PhD

The studies on “Sucker production and activation techniques in banana
(Musa spp.)” taken up at the Central Orchard of the College of Horticulture,
Vellanikkara
and
at
Regional
Agricultural
Research
Station
(RARS),
Kumarakom, Kottayam during January 2013 to September 2015. These studies
were taken up exclusively for a basic understanding of the sucker genesis (origin),
variation in sucker production of important cultivated clones with different ploidy
and genomic constitution, photosynthate and nutrient allocatory pattern to
different suckers using
14
C and
32
P and for probing the effects of physical and
cultural methods (manurial doses) of sucker activation techniques.
Among the different clones tested in the studies for sucker production,
Karpooravalli (ABB) recorded the highest number of suckers followed by
Njalipoovan (AB), Nendran (AAB), Kadali (AA), Robusta (AAA) and Bodles
altafort (AAAA) respectively. Suckering habit was positively correlated with
decreasing ploidy level and an increase in the M. balbisiana blood in the genomic
constitution of the particular clone. Kadali (AA) recorded the highest sucker
production followed by Robusta (AAA) and Bodles altafort (AAAA) within the
M. accuminata ploidy. In diploids, Njalipoovan (AB) recorded the highest number
of suckers over Kadali (AA) and in triploids, Karpooravalli (ABB) recorded the
higher number of suckers followed by Nendran (AAB) and Robusta (AAA)
respectively. Differences in sucker production were observed between the
different clones with respect to planting seasons. Kadali (AA), Njalipoovan (AB),
and Robusta (AAA) recorded the higher number of suckers in Sept-Oct planting,
whereas in case of Nendran (AAB) and Karpooravalli (ABB), Feb-March planting
recorded the best sucker production. Bodles altafort (AAAA) recorded almost the
same number of suckers in all the three plantings.
Morphological characters like plant height, collar girth and total number of
leaves recorded very strong and positive correlation with sucker characters but
negative correlation was observed with average leaf production interval. Bunch
weight recorded strong significant negative correlation with improved sucker
production and was positively correlated with number of dead suckers. Number ofdead suckers produced were found positively correlated with plant height, collar
girth, ‘D’ leaf area and average leaf production interval and almost a similar
correlation between these characters was observed in PCA and factor analysis.
The cluster analysis of six banana varieties, planted in three different
seasons (18 entries) revealed that the clones fell in four distinct clusters. NJALI-1,
NJALI-2, NJALI-3, NEND-1, NEND-3, KARP-2 and KARP-3 were grouped in
the first cluster. ROB-1, ROB-2, ROB-3 and KAD-1 were grouped in the second
cluster. KAD-2, KAD-3 and NEND-2 formed the next cluster and BOD-1,
BOD-2, BOD-3 and KARP-1 formed the last cluster. In case of cluster analysis
obtained from pooled data of six banana varieties planted in three seasons (6
entries), first cluster was composed of NJALI, NEND and KARP. Cluster II, III
and IV were composed of KAD, ROB, BOD respectively and almost similar
grouping was obtained from PCA and factor analysis.
PCA and factor analysis revealed that diversity contributed by different
banana traits for sucker production in first, second and third components was
46.8, 27.0 and 12.2 per cent respectively. The first three major factors / principle
components contributed total 85.9 per cent of the diversity. PCA and factor
analysis revealed that average dry weight of quality suckers, average dry weight
of total suckers, total number of suckers produced, number of underdeveloped
suckers produced, total number of leaves produced, number of quality suckers
produced, plant height and collar girth characters recorded their dominance in first
component/factor and were the most important traits for deciding the diversity of
banana varieties in the present study. Communality values in factor analysis
clearly revealed that the collar girth was the high relative contributory trait for
deciding sucker yield in banana.
The origin or genesis and early development of the sucker primordia was
observed in the cortex region of the mother corm and this is the first confirmatory
report on this aspect.
The photosynthesis partitioning from the mother plant to daughter suckers
using
14
C in six sucker retention intact system revealed that the last formed
suckers got maximum share of photosynthates. In case of 1 st , 2 nd and 3 rd suckerremoval as an individual treatments, more allocation of the photosynthates was
observed to the immediately next sucker and when 4 th and 5 th suckers were
removed 6 th and 3 rd suckers showed the highest recovery of
14
C, revealing the
positional effects in garnering more photosynthate. This report on actual
photosynthate translocation from the mother plant to the daughter suckers is also
the first of its kind under actual field conditions. Again this is also the first report
on the redistribution of photosynthates to daughter suckers as a consequence of
individual sucker removal.
The experiment conducted on nutrient cycling from mother plant to
daughter suckers using 32 P at two different stages i.e. fortnight before harvest and
at harvest again confirmed that the mother plant has a definite dominant role in
the distribution of nutrients and also redistribution to the daughter suckers
consequent to sucker removal that was more destructively observed when the
bunch was retained or not harvested. The very high recovery of 32 P in the mother
plant was due to the high recovery observed in the bunch.
At a fortnight before harvest, in all the treatments the highest recoveries of
32
P was observed in the mother plants. When 1 st sucker was removed the next best
recovery was observed in the 2 nd sucker followed by 4 th sucker, when 2 nd sucker
was removed the next best recovery was observed in 4 th sucker, when 3 rd sucker
was removed the next best recovery was seen in 1 st sucker followed by 2 nd sucker,
when 4 th sucker was removed the 2 nd sucker resulted the next highest recovery
followed by 5 th sucker and when 5 th sucker was removed the next highest
recovery was observed in 1 st sucker.
At the time of harvest the removal of 1 st sucker resulted the highest
recovery of the activity in the mother plant followed by 2 nd sucker. Removal of
2 nd sucker resulted the highest recovery in the 1 st sucker and mother plant. The 3 rd
sucker removal resulted the highest recovery in the 1 st sucker followed by 2 nd
sucker, removal of 4 th sucker resulted the highest recovery in the 3 rd sucker
followed by the mother plant. The removal of 5 th sucker resulted the highest
recoveries in 2 nd and 4 th sucker.Both the studies on nutrient recycling revealed a trend of higher recovery
in the immediately next sucker. The recovery was the highest in the mother plant
in the studies on fortnight before harvest due to retention of the bunch. Nutrient
redistribution pattern to daughter suckers as a consequence of phased removal of
individual suckers is also being reported for the first time.
With respect to the sucker activation techniques, the studies on physical
methods revealed that replanting the entire clump in trenches in oblique manner
ten days after harvest produced maximum total number as well as quality suckers
which performed equally well with the next best treatment of cutting the
pseudostem at half height ten days after harvest. However, the latter treatment was
the most economical one.
In case of cultural methods (manurial doses) of sucker activation,
application of NPK mixture (17: 17: 17) @ 5 and 10 g N equivalent clump -1
yielded maximum number of total as well as quality suckers, but the lower dose
was found to be more economical based on B: C ratio.