MSc

The study entitled “Air layering in selected fruit crops influenced by medium
fortified with root colonizing fungi” was conducted at the Department of Agricultural
Microbiology, College of Agriculture, Vellayani during the period 2020-2022. The
objective of the study was to investigate the effectiveness of air layering medium fortified
with Piriformospora indica and/or Glomus fasciculatum on rooting and the establishment
of layers of selected fruit crops.
An initial experiment was conducted to evaluate the survival of the root colonizing
fungi in air layering medium. The tomato seedlings planted in this medium showed root
colonization with Piriformospora indica and/or Glomus fasciculatum showed
colonization at 4 and 6 weeks after planting confirming that the fungi survive in the
medium. Significant increase in IAA production was observed in tomato seedlings grown
in layering medium individually inoculated with AMF and P. indica.
Fruit crops viz., Guava, West Indian Cherry and Rambutan having varying
percentage of rooting and establishment on air layering were selected for the study. The
air layering medium fortified with Piriformospora indica (1% w/v), Glomus fasciculatum
(5% w/v), combination of Piriformospora indica and Glomus fasciculatum, and IBA
(1000 ppm) were used along with a control. Air-layering experiment with different
treatments in Guava showed significantly higher root fresh weight and dry weight in
combined inoculation of AMF and P. indica which was comparable to IBA treatment. On
propagation of successful layer in polybags it was noted that the root volume of guava
plants raised in laying medium fortified with P. indica, IBA and AMF (20.2,19.6 and
17.28 cm3
, respectively) were statistically on par and significantly higher compared to
other treatments. Guava plants grown in air layering medium fortified with P. indica
recorded the highest root fresh weight and dry weight (7.726 g and 2.49 g respectively).
On observation of root colonization of fungi, it was seen that P. indica colonized only in
the inoculated plants and but native AMF was found to colonize all guava plants.
In similar studies in West Indian Cherry, layers grown in G. fasciculatum fortified
medium recorded the highest number of primary roots, root volume (0.42 cm3
), root fresh
weight (0.406 g) and root dry weight (0.04 g). Treatment with IBA was on par with AMF
treatment in the number of roots and root fresh weight. The percentage of successful
layers was significantly high in the treatment combination of P. indica and AMF (86
percent).
In in vivo study on establishment of rooted layers of West Indian Cherry planted
in polybags, shoot length (67.4 cm), root length (51.2 cm), root volume (25.6 cm3
), shoot
fresh weight (27.666 g), dry weight (17.326 g), root fresh weight (8.26 g) and dry weight
(3.956 g) were significantly higher in plants grown in air layering medium fortified with
P. indica when compared to control. As in the case of Guava plants, West Indian Cherry
also showed colonization by native AMF even in control plants but P. indica colonization
was observed only in P. indica inoculated plants.
The same sets of experiments in Rambutan revealed induction of callus formation
in the wounded region two months after layering and rooting three months after air
layering in medium fortified with P. indica and G. fasciculatum. Even though there was
rooting, the number of successful layers were less and those rooted layers, when planted
in the polybags for further study, dried off.
Results of the present study suggest that fortification of air layering medium with
root colonizing fungi viz., Piriformospora indica and Glomus fasciculatum can improve
rooting and establishment of layers in Guava and West Indian cherry and the results are
comparable to that of IBA treatment at 1000 ppm