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Plant Gene and Trait, 2013, Vol.4, No.4, 17
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plant productivity, as they are responsible for capturing
light energy and using it as a driving force for
producing the assimilates. Water deficit induces
disintegration of thylakoid membranes and causes
degradation of chlorophyll pigments. This could
substantially contribute to the overall inhibition of
photosynthesis in leaves of water deficit plants
(Farquhart et al., 1982). As observed in the present
study, the water deficit caused considerable reduction
in chlorophyll content during shooting stage (7
th
MAP)
of about 5 to 18 per cent in Matti, Matti ×Anaikomban,
Matti × cultivar rose and Pisang jajee × Matti over
control. The mechanism of reduction in chlorophyll
content due to the enhancement of chlorophyllase
activity in water stressed plants could be the cause for
chlorophyll degradation. Ghavami (1973) noticed a
drastic reduction in the total chlorophyll content under
water deficit condition due to the disruption of fine
structure of chloroplast and instability of pigment and
enhanced chlorophyllase activity. Thomas and Turner
(2001) also observed a decrease in chlorophyll content
in banana cultivars leading to decrease in photosynthesis.
Besides these results, Alberte et al. (1977) reported
that water deficit also caused similar inhibitory effect
on chlorophyll content in Jack bean. Water stressed
plants suffered reduction in chlorophyll level probably
due to the action of reactive oxygen species, mainly
by hydrogen peroxide that is accumulated under water
deficiency, because its provokes the inactivation/
oxidation of the pigments pre-existing in chloroplast
(Patonnier et al., 1999). Similar to this finding, Havaux
et al. (1991) noticed a decreased in chlorophyll content
leads to the reduction of oxidized quinon-A portion,
thus representing a fraction of PS-
Ⅱ
centers prone to
suffer photoinhibitory damages by chronic over
excitation and subsequent changes in D
1
protein.
Besides these results, Robinson and Bower (1988)
reported that resistant banana cultivars maintained
higher amount of total chlorophyll content at the
active growth stage. In the present study also, the
cultivars of Karpuravalli, Karpuravalli × Pisang jajee,
Saba and Sannachenkathali recorded lesser reduction
in total chlorophyll content with only 5 to 8 per cent
loss due to water deficit and thereby maintained
higher level of total chlorophyll content than the other
cultivars. It was also exhibited that higher leaf relative
water content induced increase in total chlorophyll
content due to higher amount of chlorophyll ‘a’ under
water stress conditions (Turner et al., 2007). Graan
and Boyer (1990) found that accumulating higher
photosynthetic pigments in leaves under water
stressed conditions could help capture more light
energy per unit leaf area thus improve photosynthetic
capacity per unit leaf area in water stressed plants.
3.2 Soluble protein (mg/g)
Progressive increasing trend of soluble protein content
was observed from 3
rd
to 7
th
MAP stage with a
remarkable decline towards harvest (Table 2). The two
main plot treatments differed significantly, with the
higher value of 11.2 mg/g being recorded by M1 at 7
th
MAP stage. Treatment M
2
(9.9 mg/g), however,
recorded around 13 per cent lesser soluble protein
content than M1 at the same stage of growth. Among
the sub-plot treatments, S
1
registered higher soluble
protein content of 12.7 mg/g. Other treatments viz., S
3
,
S
4
, S
7
, S
8
and S
10
were on par with each other, and
their performance were significantly lesser than S
1
(12.7 mg/g). Interaction effects of M at S and S at M
revealed significant differences at all the stages of
growth. The treatment M
1
S
1
recorded higher soluble
protein content of 13.3 mg/g followed by M
1
S
5
(12.1 mg/g). However, a considerable reduction per
cent trend could also be noticed in soluble protein
content due to interaction of M
2
and subplot
treatments. M
2
S
1
, M
2
S
2
, M
2
S
3
and M
2
S
4
was found
better than the other treatments in recording about 9 to
11 per cent reduction, whereas, M
2
S
5
to M
2
S
12
was
found to show reduction with 13 to 18 per cent in
soluble protein content over the M1 and sub plot
treatments.