Harnessing arbuscular mycorrhizal fungi (AMF) for quality seedling stock production of Tectona grandis Linn. and Swietenia macrophylla King

Abstract

A study was conducted to find efficacy of three native species of arbuscular mycorrhizal fungi (AMF) on Tectona grandis Linn. and Swietenia macrophylla King. at Tree nursery, College of Forestry, Vellanikara, Thrissur, Kerala during 2013-2015. The study assessed the impact of inoculation of selected AMF on growth and quality of seedlings. The native AMF species (Funelliformis mosseae, Glomus intradices, Glomus proliferum) at different levels (10, 20 and 50 g inoculum per seedling) were applied on the seedlings raised in polythene bags. The experiment was laid out in a factorial RBD with control. Seedlings raised in the presence of AMF showed a significant difference in plant growth and quality over those grown in the absence of AMF. The extent of growth and quality enhancement differed among AMF species and levels of inoculation. In general, mycorrhizal symbiosis significantly improved plant growth performance, such as plant height, stem diameter, shoot, root or total dry weight. Mycorrhizal colonization of seedlings ranged from 17.3 per cent to 56.3 per cent in S. macrophylla and 15.0 per cent to 36.0 per cent in T. grandis. The growth observations like LAR, LWR, LAD, SLA, SLW, AGR, RGR and NAR showed a significant difference among the treatments in S. macrophylla and T. grandis seedlings. With a few exceptions, seedling growth observations and physiological parameters improved with AMF inoculation. Mycorrhizal inoculations significantly influenced chlorophyll content, photosynthetic rate, transpiration rate, plant water potential, stomatal conductance, relative water content and leaf temperature in S. macrophylla seedlings. In case of T. grandis seedlings, chlorophyll content, leaf temperature and relative water content were influenced by AMF inoculation. While photosynthetic rate, transpiration rate, stomatal conductance and plant water potential were not influenced by AMF. The Mycorrhizal Efficiency Index (MEI) in S. macrophylla was 66.43 per cent for F. mosseae at higher level (50 g inoculum), while in T. grandis MUE was 89.23 per cent on G. proliferum at higher level (50 g inoculum). Root colonization per cent at lower level (10 g inoculum) was found to range from 15.00 to 24.33 per cent in case of S. macrophylla, while it ranged from 34.33 to 55.67 per cent at higher level (50 g inoculums) of inoculation. In T. grandis, at lower level (10 g inoculum) root

colonization was found to range from 17.33 to 33.33 per cent, while it ranged from 22.67 to 56.33 per cent at higher level (50 g inoculum) of inoculation.By looking at overall parameters studied, it can be concluded that F. mosseae at 50 g of inoculum at the time of transplanting @ 10 spores /g confers maximum growth and seedling quality benefits in nursery as compared to all other fungi used in for S. macrophylla. Seedlings of T. grandis with G. proliferum at 50 g inoculums performed better in nursery. This technology has the potential to reduce the nursery period and increase in quality of seedlings produced resulting in considerable economic gains.