MSc

The experiment entitled " Physiological and biochemical studies on growth,development and yield of ginger (Zingiber officinale Rosc.) as influenced by bionoculants and phosphorus fertilization," was undertaken at Department of Plant Physiology, College
of Agriculture, Vellayani during 2016-18. The objective of the study was to elicit
information on the physiological, biochemical attributes on plant growth, development and
yield of ginger as influenced by bioinoculants such as mycorrhiza and Trichoderma viride
combined with phosphorus fertilization.
In this study ginger cultivar maran was grown in pots under completely randomized
block design (CRD). Different levels of ‘P’ were applied to soil in pots viz. low (P2O5 -50%
POP), medium (P2O5 as per POP) and high (P2O5 double dose of POP). The pots were
inoculated with AMF or Trichoderma or both together in combination as per the treatments
during the time of planting. Control plants were also maintained. The treatments were T1-
control(P2O5 as per POP ),T2(P2O5 as per POP +AMF),T3 (P2O5 as per POP
+Trichoderma), T4( P2O5 as per POP +AMF+ Trichoderma),T5 (P2O5-50% of POP),T6 (
P2O5-50% of POP +AMF),T7( P2O5-50% of POP +Trichoderma),T8 (P2O5-50% of POP
+AMF+ Trichoderma ), T9 (P2O5-Double dose of POP), T10 (P2O5-Double dose of POP
+AMF),T11 (P2O5-Double dose of POP +Trichoderma) and T12(P2O5-Double dose of
+AMF+ Trichoderma).
Effect of microbial inoculation and phosphorous fertilization on growth parameters
such as shoot height, number of leaves , number of tillers and fresh ginger yield were
observed at fourth ,sixth and eighth month. T6 recorded highest plant height up to sixth
month but at eighth month, T8 recorded 42% increase in shoot height over control. T8
recorded maximum number of leaves and was found on par with T4 and T6. At maturity
stage 64.2 % increases in number of tillers were observed in both treatments T4 and T6
than control. At final stage maximum fresh weight of ginger was recorded in T8 .At fourth
month highest rhizome fresh weight was recorded in treatment T8 and was on par with T4.
At sixth month maximum rhizome fresh weight was noticed for the treatment T8 and was
on par with T6 .Plants which did not receive any microbial inoculation showed less values
for all the above parameters at all stages.
Physiological parameters such as photosynthetic rate, transpiration rate, stomatal
conductance and leaf temperature did not show any significant difference at maturity stage.
Treatment T8 recorded maximum value at fourth and sixth month for these parameters. A
significant difference was observed among the treatments for chlorophyll and carotenoid
content. Total chlorophyll content showed an increase in trend but at maturity chlorophyll
content decreased in all treatments due to senescence. Throughout the growth stages, T8
recorded significantly higher value for chlorophyll a and total chlorophyll content.
Chlorophyll stability index and cell membrane stability index of the plants under different
treatments were found to be significantly different and treatment T8 recorded maximum
value in all stage of analysis. Uptake of major nutrients such as N, P, K, Ca and Mg
increased with microbial inoculation. Treatment T8 with combined inoculation of AMF
and trichoderma and half dose of ‘P’ showed 49.2%, 58.4%, 120.6% and 20% increase in
total protein, total sugar, phenol and reducing sugar content respectively at maturity stage.
Significant difference existed for AMF colonisation percentage and AMF spore count
between the treatments. Treatment T8 recorded maximum value for both the parameters
along with T4 and T6.At sixth month AMF colonisation reached 100% for treatment T8. A
decrease in trend was observed at final stage due to wilting of roots.
Effect of microbial inoculants on yield parameters such as fresh weight, dry weight,
rhizome thickness, rhizome spread and harvest index were studied. Treatment T8 recorded
35.5% and 39.2% increase in fresh and dry ginger yield over control. Highest rhizome
spread was observed in treatment T8 and was found on par with T4 and T12 and the lowest
value was obtained in control and T5. Rhizome thickness was recorded maximum in the
treatment T8 and was found on par with T3, T4, T6 and T10. At maturity stage there was
significant difference among the treatments for the harvest index. Volatile oil content at
maturity stage ranged between 1.5% to 3% for different treatments. Treatment T8 recorded
65.7% increase in volatile oil content over control. Treatment T8 recorded highest oleoresin
content (65.8%) and was on par with T6. Starch content also recorded highest value for
treatment with half dose of phosphorus and combined application of microbes. This
treatment recorded 28.8 % increase in starch content than control. Decrease in crude fibre
content increase the quality of ginger. Microbial inoculation resulted in reduction of crude
fibre content in ginger rhizomes. Maximum fibre content was recorded for the treatment T9
followed by control. Least value was recorded for treatment T8. Gingerol content was
estimated by HPLC analysis. Gingerol is an important phytochemical which impart
medicinal property to ginger. Microbial inoculation significantly changed gingerol content
.Treatment T4 (0.96%) followed by T8 (0.85%) recorded highest value.
Arbuscular mycorrhizal and trichoderma inoculation along with phosphorous
fertilization has significantly improved growth ,yield and quality of ginger not only
through increasing nutrient uptake, but also viz. stimulating photosynthetic parameters and
biochemical properties of the ginger particularly under low phosphorous fertilization.
Number of tillers, number of leaves and yield was recorded maximum for the treatments
with microbial application. This was mainly due to increase in uptake of nutrients,
especially in rhizome of ginger. Microbial inoculation increased total protein content,
reducing sugar, total sugar content in ginger. However, these benefits in response to the
microbial inoculation generally decreased when there was an increase in P fertilizer added
to the soil, suggesting that phosphorous reduced AMF colonization and the corresponding
effects. Microbial inoculation resulted in enhanced production of phenolic compounds such
as gingerol (65.4 % increase over control) in rhizomes. Therefore the best treatment
identified is half dose of phosphorous and combined inoculation of AMF and trichoderma.
Hence it is concluded that microbial inoculation could replace fertilization application,
especially the recommended dose of ‘P’ fertilization up to 50 %. It enhanced growth,
development and yield of ginger. It is a feasible technique for the production of ginger
plants with increased quantities of oleoresin and volatile oil and also to improve the
medicinal value of ginger by increasing gingerol content.