RESUMO

To optimize nursery practices for efficient plant production procedures and to keep up to the ever growing demand of seedlings, identification of the most suitable species of arbuscular mycorrhizal fungi (AMF), specific for a given tree species, is clearly a necessary task. Sixty days old seedlings of Neem (Azadirachta indica A. Juss) raised in root trainers were inoculated with six species of AMF and a mixed inoculum (consortia) and kept in green house. Performances of the treatments on this tree species were evaluated in terms of growth parameters like plant height shoot collar diameter, biomass and phosphorous uptake capabilities. Significant and varied increase in the growth parameters and phosphorous uptake was observed for most of the AMF species against control. Consortia culture was found to be the best suited AMF treatment for A. indica, while Glomus intraradices and Glomus mosseae were the best performing single species cultures. It is the first time in the state of Gujarat that a wide variety of AMF species, isolated from the typical semi-arid region of western India, were tested for the best growth performance with one of the most important tree species for the concerned region.

Assuntos

RESUMO

Nutrient dynamics in forest plantations of Azadirachta indica (Meliaceae) established for restoration of degraded lands in Colombia. Azadirachta indica is a tree species which use is steadily increasing for restoration of tropical and subtropical arid and degraded lands throughout the world. The objective of this research study was to evaluate the potential of these plantations as an active restoration model for the recovery of soils under desertification in arid lands of Colombia. Litter traps and litter-bags were installed in twenty 250m2 plots. Green leaves and soil samples inside and outside this species plantations were taken, and their elemental concentrations were determined. Litterfall, leaf litter decomposition and foliar nutrient resorption were monitored for one year. The annual contributions of organic material, such as fine litterfall, represented 557.54kg/ha, a third of which was A. indica leaves. The greatest potential returns of nutrients per foliar litterfall were from Ca (4.6kg/ha) and N (2.4kg/ha), and the smallest potential returns came from P (0.06kg/ha). A total of 68% of the foliar material deposited in litter-bags disappeared after one year. The greatest release of nutrients was that of K (100%), and the least was that of N (40%). P was the most limiting nutrient, with low edaphic availability and high nutrient use efficiency from Vitousek's index (IEV = 3176) and foliar nutrient resorption (35%). Despite these plantations are young, and that they have not had forestry management practices, as an active restoration model, they have revitalized the biogeochemical cycle, positively modifying the edaphic parameters according to the increases in organic material, P and K of 72%, 31% and 61%, respectively. Furthermore, they improved the stability of aggregates and the microbe respiration rates. The forest plantation model with exotic species has been opposed by different sectors; however, it has been acknowledged that these projects derive many benefits for the restoration of biodiversity and ecosystemic functions. The conditions of severe land degradation demand the initial use of species, such as A. indica, that can adapt quickly and successfully, and progressively reestablish the biogeochemical cycle.

Assuntos

RESUMO

Azadirachta indica is a tree species which use is steadily increasing for restoration of tropical and subtropical arid and degraded lands throughout the world. The objective of this research study was to evaluate the potential of these plantations as an active restoration model for the recovery of soils under desertification in arid lands of Colombia. Litter traps and litter-bags were installed in twenty 250m² plots. Green leaves and soil samples inside and outside this species plantations were taken, and their elemental concentrations were determined. Litterfall, leaf litter decomposition and foliar nutrient resorption were moni- tored for one year. The annual contributions of organic material, such as fine litterfall, represented 557.54kg/ha, a third of which was A. indica leaves. The greatest potential returns of nutrients per foliar litterfall were from Ca (4.6kg/ha) and N (2.4kg/ha), and the smallest potential returns came from P (0.06kg/ha). A total of 68% of the foliar material deposited in litter-bags disappeared after one year. The greatest release of nutrients was that of K (100%), and the least was that of N (40%). P was the most limiting nutrient, with low edaphic availability and high nutrient use efficiency from Vitousek´s index (IEV=3176) and foliar nutrient resorption (35%). Despite these plantations are young, and that they have not had forestry management practices, as an active restoration model, they have revitalized the biogeochemical cycle, positively modifying the edaphic parameters according to the increases in organic material, P and K of 72%, 31% and 61%, respectively. Furthermore, they improved the stability of aggregates and the microbe respiration rates. The forest plantation model with exotic species has been opposed by different sectors; however, it has been acknowledged that these projects derive many benefits for the restoration of biodiversity and ecosystemic functions. The conditions of severe land degradation demand the initial use of species, such as A. indica, that can adapt quickly and successfully, and progressively reestablish the biogeochemical cycle.

Azadirachta indica A. Juss (Nim) ha sido ampliamente empleada en procedimientos de restauración, por lo tanto se evaluó el potencial de sus plantaciones para restaurar tierras secas degradadas por sobrepastoreo, vía reactivación del ciclo biogeoquímico. En 20 parcelas de 250m², se instalaron trampas de hojarasca y litter-bags. Se tomaron muestras de hojas maduras y de suelos dentro y fuera de las plantaciones, y se determinaron sus contenidos elementales. Fueron monitoreados la caída de hojarasca, la descomposición de hojarasca y la reabsorción de nutrientes foliares durante un año. Los aportes anuales de hojarasca fina representaron 557.54kg/ha (33% hojas de Nim). Los mayores retornos potenciales de nutrientes vía foliar fue- ron de Ca (4.6kg/ha) y N (2.4kg/ha) y los menores de P (0.06kg/ha). El 68% del material se descompuso tras un año. La mayor liberación de nutrientes fue de K (100%) y la menor de N (40%). El P fue el nutriente más limitante, con baja disponibilidad edáfica y alta eficiencia en su uso según el Índice de Vitousek (IEV=3 176) y la reabsorción foliar (35%). Estas plantaciones juveniles demostraron efectividad en la reactivación del ciclo biogeoquímico, que mejoraron parámetros edáficos, según incrementos de materia orgánica, P y K; 72%, 31% y 61%, respectiva- mente. Además mejoraron la estabilidad de agregados y las tasas de respiración microbiana.

Assuntos

RESUMO

To optimize nursery practices for efficient plant production procedures and to keep up to the ever growing demand of seedlings, identification of the most suitable species of arbuscular mycorrhizal fungi (AMF), specific for a given tree species, is clearly a necessary task. Sixty days old seedlings of Neem (Azadirachta indica A. Juss) raised in root trainers were inoculated with six species of AMF and a mixed inoculum (consortia) and kept in green house. Performances of the treatments on this tree species were evaluated in terms of growth parameters like plant height shoot collar diameter, biomass and phosphorous uptake capabilities. Significant and varied increase in the growth parameters and phosphorous uptake was observed for most of the AMF species against control. Consortia culture was found to be the best suited AMF treatment for A.indica, while Glomus intraradices and Glomus mosseae were the best performing single species cultures. It is the first time in the state of Gujarat that a wide variety of AMF species, isolated from the typical semi-arid region of western India, were tested for the best growth performance with one of the most important tree species for the concerned region.

Assuntos