Species-specific Resource Allocation Shifts in Teak (Tectona grandis) and Sandal (Santalum album) Seedlings under Arbuscular Mycorrhizal Fungi Inoculation
K. Shiran *
College of Forestry, Kerala Agricultural University, Thrissur, Kerala 680 656, India and ICAR-Central Arid Zone Research Institute, RRS, Jaisalmer, Rajasthan, 345001, India.
A. V. Santhoshkumar
College of Forestry, Kerala Agricultural University, Thrissur, Kerala 680 656, India.
Joy Michal Johnson
Department of Plant Pathology, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala, 695522, India.
Binu N Kamalolbhavan
College of Forestry, Kerala Agricultural University, Thrissur, Kerala 680 656, India.
T. K. Kunhamu
College of Forestry, Kerala Agricultural University, Thrissur, Kerala 680 656, India.
M. N. Ashwath
College of Forestry, Kerala Agricultural University, Thrissur, Kerala 680 656, India and College of Agriculture, Gangavathi, University of Agricultural Sciences, Raichur, Karnataka -583 227, India.
Keisham Bindyalaxmi
College of Forestry, Kerala Agricultural University, Thrissur, Kerala 680 656, India.
*Author to whom correspondence should be addressed.
Abstract
Arbuscular Mycorrhizal Fungi (AMF) are ecologically significant symbionts that enhance nutrient acquisition, stress tolerance, and early establishment in a wide range of plants. Their influence on resource allocation strategies in forestry species, however, remains less explored. This study evaluated the effects of AMF consortia (Funneliformis mosseae, Entrophospora etunicata and Rhizophagus fasciculatus) on germination dynamics and seedling growth of teak (Tectona grandis L. f.) and sandal (Santalum album L.), two tropical tree species of high economic importance. Seeds were pretreated to overcome dormancy and raised in sterilized coir pith and farmyard manure substrate, with or without AMF inoculation. Germination performance was assessed through indices such as germination percentage, mean germination time, germination index, and mean daily germination, while seedling traits including shoot and root growth, biomass partitioning, root volume, leaf number, and leaf area of one year old seedlings were measured. Germination percentage remained unaffected by AMF (teak: 0.55 vs. 0.53; sandal: 0.70 vs. 0.70). However, species-specific growth responses emerged. In teak, AMF inoculation significantly increased root biomass (5.88 g vs. 4.43 g) and leaf area (203 cm² vs. 126 cm), despite reducing leaf number (6.7 vs. 16.3). Sandal showed moderate but non-significant improvements in root weight (372 mg vs. 210 mg) and leaf area (16.6 cm² vs. 15.1 cm²). These results indicate that AMF inoculation drives host-dependent resource allocation shifts favoring below-ground and photosynthetic investments in teak, and modest enhancements in sandal highlighting their potential in sustainable forestry nursery practices.
Keywords: Arbuscular mycorrhizal fungi, germination, biomass allocation, Tectona grandis, Santalum album, nursery management, Plant–microbe interactions