Salinity stress effects on the growth, morphological, physiological, and biochemical properties of Melia (Melia dubia Cav.) plant

Salinity stress severely affects the growth, physiological and developmental processes in plant species. Melia dubia is an ecologically and economically important tree species of the Indian subcontinent. However, systematic information with respect to the species salt tolerance potential is completely lacking. Under salt stress conditions, determining suitable soil EC range is required for the better survival, growth and productivity of the tree species. In present study, we investigated the effects of different soil salinity (EC 4, 8, and 12) levels on the ion homeostasis, physio-biochemistry, morphology, and growth of M. dubia plant. Results revealed that increase in soil salinity causes higher Na+ content and Na+/K+ ratio, while lower K+ content, in the leaf tissues of M. dubia. The physiological processes such as the photosynthetic rate, stomatal conductance, internal CO2 concentration, and transpiration rate were adversely affected with the increased salt stress levels. Morphological parameters, such as internodal length, petiole length, leaf length, and leaf width also decreased (P<0.05) under saline stress conditions. Results further indicated that salinity levels significantly (P<0.05) affected the M. dubia growth, and the growth rate was found optimum upto 8 EC, thereafter it slightly decreased with the increased salt stress to 12 EC. Our findings showed that increased salinity stress causes significant changes in the physiological, morphological, and growth pattern of M. dubia. Therefore, based on present experiment, we found M. dubia suitable for the salt affected soils of EC 8 with optimum growth rate and at EC 12 with the moderate (20–25%) growth reduction.

Water Availability Controls the Biomass Increment of Melia dubia in South India

Farmland tree cultivation is considered an important option for enhancing wood production. In South India, the native leaf-deciduous tree species Melia dubia is popular for short-rotation plantations. Across a rainfall gradient from 420 to 2170 mm year–1, we studied 186 farmland woodlots between one and nine years in age. The objectives were to identify the main factors controlling aboveground biomass (AGB) and growth rates. A power-law growth model predicts an average stand-level AGB of 93.8 Mg ha–1 for nine-year-old woodlots. The resulting average annual AGB increment over the length of the rotation cycle is 10.4 Mg ha–1 year–1, which falls within the range reported for other tropical tree plantations. When expressing the parameters of the growth model as functions of management, climate and soil variables, it explains 65% of the variance in AGB. The results indicate that water availability is the main driver of the growth of M. dubia. Compared to the effects of water availability, the effects of soil nutrients are 26% to 60% smaller. We conclude that because of its high biomass accumulation rates in farm forestry, M. dubia is a promising candidate for short-rotation plantations in South India and beyond.

Growth and Yield Performance of Black Gram (Vigna mungo L.) under Malabar Neem (Melia dubia) Plantations in Western Zone of Tamil Nadu

Background: Black gram (Vigna mungo. L) is one of the most cultivated legume pulse crop with high nutritive value and Malabar neem (Melia dubia) is an emerging industrial agroforestry tree in Southern India. To maximize the land utilization with a field experiment was conducted at Western zone of Tamil Nadu to investigate the performance of black gram varieties under different spatial arrangements of Melia dubia plantations. Methods: An agroforestry trial was laid out in randomized block design (RBD) with eight treatments and three replications during kharif and rabi (2019-20) season. Black gram crop varieties (V1 - CO6 and V2 - VBN 6) were intercropped with M. dubia (1.5 year old plantation) with three different spacing of S1 (3 x 1.5 m), S2 (3 x 3 m) and S3 (4 x 4 m) while S0 as open field (Sole crop of black gram) for both the season. Result: The results of pooled analysis of two season shown that, treatment S0V2 recorded plant height (49.96 cm), number of branches (3.76), number of leaves (259.75), number of flowers (53.44), number of pods (22.85), seed yield per plant (5.38 g) and seed yield per hectare (0.82 tonnes) in open condition. Similarly in intercropping the growth and yield attributes of black gram were minimum performance recorded in CO 6 at closer spacing (3 x 1.5 m). In tree growth maximum pooled height increment (1.57 m) was observed in closer spacing (3 x 1.5 m) and maximum diameter recorded in wider spacing of both varieties. Hence wider spacing of S3 (4 x 4 m) can be suggested for intercropping under M. dubia plantations upto 4 years.

Arbuscular Mycorrhizal Fungal Diversity In Medicinal Plants Of Sirumalai Hills, Eastern Ghats And Their Role In Melia Dubia Cav

The microbial World is the largest unexplored reservoir of biodiversity on earth. Interest in the exploration of microbial diversity has been promoted by the fact that a microbe performs numerous functions essential for the biosphere that include nutrient cycle and environmental detoxification. Notably, under natural circumstances, plants frequently interact with microbes,which directly arbitrate plant responses to environmental adversities. Some microbe-plant interactions lead to a mitigation of stress-related damages and improvement of plant tolerance to stressful conditions. As a crucial element of soils, microbes are an integral part of the agricultural ecosystem.

LIMONOIDS FROM FRUITS OF Melia dubia Cav. IN VIETNAM

A phytochemical study on fruits of Melia dubia Cav. collected in Nghe An province led to the isolation of three secondary metabolites, including 21α-O-methylmelianodiol (1), 21β-O-methylmelianodiol (2) and (21S,23R,24R)-21,23-epoxy-24-hydroxy-21β-methoxytirucalla-7,25-dien-3-one (3). The chemical structures of these compounds were determined on the basis of 1D, 2D NMR, UV, IR and MS analytical results and comparison with reported data. All three compounds (1–3) were isolated from this plant for the first time.