Arbuscular mycorrhizal associations in different forest tree species of Hazarikhil forest of Chittagong, Bangladesh

Biodiversity of arbuscular mycorrhizal （AM） colonization and AM fungal spores were studied in the roots and rhizosphere soils of ,4cacia catechu （L.f）. Wild., A. mangium Willd, Anthocephala cadamba Miq., Artocarpus chaplasha Roxb., Chickrassia tabularis A. Juss., Swie- tenia macrophylla King., Tectona grandis L. from plantations; Albizia procera （Roxb.） Benth., ,4. falcataria L., Alstonia scholaris （L.） R. Br., ,4phanamixis polystachya （Wall.） Parker., Hydnocarpus kurzii （King.） Warb., Heynea trijuga Roxb., Lagerstroemia speciosa （L.） Pers., Messua ferrea Linn., Podocarpus nerifolia Don., Swintonia floribunda Griff., Syzygiumfruticosum （Roxb.） DC., S. grandis （Wt.） Wal. from forest and nursery seedlings of A. polystachya, A. chaplasha, Gmelina arborea Roxb. and S. cuminii （L.） Skeels from Hazarikhil forest, Chittagong of Bangladesh. Roots were stained in aniline blue and rhiz0sphere soils were assessed by wet sieving and decanting methods. The range of AM colonization varied significantly from 10%-73% in the plantations sam- ples. Maximum colonization was observed in A. mangium （73%） and minimum colonization was observed in C. tabularis （10%）. Vesicular colonization was recorded 15%-67% in five plantation tree species. The highest was in A. cadamba （67%） and the lowest was in T. grandis; A. chaplasha and C. tabularis showed no vesicular colonization. Arbuscular colonization was recorded 12%-60% in four plantation tree species. The highest was in .4. mangium （60%） and the lowest was in A. cadamba. Roots of Artocarpus chaplasha, C. tabularis and T. grandis showed no arbuscular colonization. Among 12 forest tree species, nine tree species showed AM colonization. The highest was in A. falcataria （62%） and the lowest was in S. fruticosum （10%）. Significant variation in vesicular colonization was recorded in seven forest tree species. The highest was in H. trijuga （52%） and the lowest was in L. speciosa 08%）. Hydnocarpus kurzii, M. ferrea, P. nerifolia S. fruticosum and S. grandis showed no vesicular colonization. Arbuscular colonization was recorded in sevenforest tree species. The highest was inA. falcataria （60%） and the lowest was in A. procera （10%）. All the nursery seedlings showed AM coloniza- tion and the range was 10%-73%. Vesicules were recorded in G. arbo- rea （40%） and S. cumini （40%）. Arbuscular colonization was recorded in G. arborea （100%） and S. cumini （100%）. Spore population was re- corded 77-432/100 g dry soils, 80-276/100 g dry soils, and 75-153/100g dry soils in plantation, forest and nurse.ry, respectively. Glomus and Acaulospora were dominant genera among the six AM fungi recorded. Significantly positive correlation was observed between/AM colonization and AM fungal spore population in Hazarikhil plantation tree species, forest tree species and nursery tree seedlings. The present study showed the biodiversity of root colonization and AM fungi are active in nutrient cycling, survivals and seedling establishment of the plants in the Hazarikhil forest, plantation and nursery.

Effect of Rhizobium inoculation on Growth and Nodulationof Albizzia procera, Albizzia lebbeck and Leucaena leucocephala

Effects of inoculation of Rhizobium suspension on nodulation and plant growth were examined withAlbizzia procera, Albizzia lebbeck and Leucaena leucocephala seedlings grown on sterilized and non-sterilizedsoil media. Inoculation resulted in nodule number increases of 28.6, 29.02 and 23.9 times in sterilized soiland 3.4, 3.6 and 3.27 times in non-sterilized soil for A. parocera A. lebbeck and L. leucocephala seedlingsrespectively. Total dry mass increased by 127.6%, 66.7% and 60.7% in sterilized soil and 100%, 95.5%and 52.65% in non-sterilized soil for these three legume trees, respectively, after a period of two months.Significalltly high inoculation responses of root length, root diameter, collar diameter, shoot length, and drymass of root, shoot, leaves and nodules were also observed in both sterilized and non-sterilized soil media ascompared to respective control treatments. The response to inoculation was strong in sterilized and modestin non-sterilized soils. The significantly higher response to Rhizobium inoculation over control in all thespecies tested suggested that application of Rhizobium greatly enhanced plant growth, nodulation, biomassproduction and nitrogen-fixing activity of the nodules.

Biodiversity of arbuscular mycorrhizal colonization and spore population in different agroforestry trees and crop species growing in Dinajpur,Bangladesh

Biodiversity of arbuscular mycorrhizal colonization and spore population was investigated in different agroforestry trees and crop species collected from different locations of Dinajpur district of Bangladesh. Roots and rhizosphere soils of Albizia procera Benth., Capsicum frutescens L, Curcuma domestica Vahl., Dalbergia sissoo Roxb. and Swietenia macrophylla King. from Dashmail; C. domestica, D. sissoo, Eucalyptus camaldulensis Dehnn., Gmelina arborea （Roxb） DC and Oryza sativa L. from Kantaji and C. domestica, D. sissoo, Litchi chinensis Sonn. and O. sativa from Ramsagar were collected. Roots and soils were assessed following standard methods. The range of AM colonization was recorded 36%-79% from Dashmail. The highest AM colonization was recorded in C. frutescens （79%） and the lowest was in C. domestica （36%）. The range of colonization was recorded as 33%-70% from Kantaji. The highest AM colonization was recorded in G. arborea （70%） and the lowest was in O. sativa （33%）. The range of AM colonization was recorded as 35%-70% from Ramsagar. The highest AM colonization was recorded in D. sissoo （70%） and the lowest was in O. sativa （35%）. Arbuscular mycorrhizal spore population varied from 54 to 140/100g dry soil in the soils from Dashmail. The highest was in the soils of D. sissoo （140） and the lowest was in C. domestica （54）. The spore population varied from 63 to 221 in Kantaji. The highest was in G. arborea （221） and the lowest was in O. sativa （63）. The range population in Ramsagar varied from 69 to 160. The highest was recorded in D. sissoo （160） and the lowest was in L. chinensis （69）. No significant relationship of soil pH and soil OM with AM colonization and with spore population was observed. Simpson＇s index of diversity （Ds） and Shannon＇s index of diversity- （Hs） were highest in the soil of D. sissoo from Kantaji and the lowest in the soils of O. sativa from Ramsagar. Biodiversity of AM colonization, spore population and the distribution of AM fungi in the rhizosphere soils of different agroforestry plants indicated the occurrence of AM fungi, mycotrophic nature of the trees and crop species, contribution and necessity of AM fungi and the AM dependence of the agroforestry plants growing in Dinajpur district of Bangladesh.