says Nawaz Yasin Islam
TREES HAVE been nurtured by farmers on farms, pasture land and around homes for millennia to satisfy the livelihood needs of many. These were later on defined as multipurpose trees which provided fodder, firewood and at the same time replenished the depleted nutrient reserves of the soil.
Many strides have been made to define, characterize and evaluate multi-purpose tree species for various agroforestry systems under different agro-ecological zones of the world.
Parkia roxburghii G. Don is a lesser known multipurpose tree species of family Mimosaceae. It grows abundantly in the North Eastern region of India, especially in Manipur, Mizoram and Nagaland. It has significant economic values as vegetable, medicinal, Industrial and fire wood in this region. It is a fast growing, easier to grow and hardy in nature.
It produces a crop even under adverse soil and climatic conditions. This tree is suitable for reclamation of abandoned jhum lands and also as agro-forestry plantations. If properly exploited, it can serve as supplementary source of vegetable proteins and edible oil.
The importance of agroforestry this tree is at par with any other important tree species for sustenance in the region of Meghalaya. The species will act as shade tree, add extra income to the growers and subsequently nourishes the soil by fixing atmospheric nitrogen. In favourable season, a mature tree can fetch approximately Rs. 8,000-10,000 per annum to the grower. The seed and fruit contain about 54% fat and 30% protein besides containing equivalent amount of vitamins and minerals as other commercial beans. The seeds and fruits cures stomach disorders, regulate liver functions and potential insecticide on aphids. The bark is used for curing toothache, stomach upset and diarrhoea, and in making lotion for skin diseases and finds use in the tanning industry.
Kitbok Nongrum, a lecturer at the Department of Environment Sciences & Traditional Ecosystems at the Martin Luther Christian University (MLCU) and a firm believer of the boundless potential in the medicinal plants of Meghalaya carried out the much needed research into this arena. He was initially involved in a project on screening tree bean genotypes from Northeastern India under the supervision of BP Bhatt, HOD Agroforestry Division, ICAR Umiam, came to know more about the species and was fascinated to witness its contribution to people of the region. This led to Nongrum pursuing deeper into the subject during the course of his PhD in Botany Department, NEHU under Uma Shankar.
This was the beginning of years of research on the ‘Effect of provenance variation on seed characteristics, germination and seedling growth of tree bean’ (Parkia roxburghii G. Don). Provenance in forestry refers to the population of trees growing at a particular place of origin. Provenance research defines the genetic and environmental components of phenotypic variation associated with geographic source. Information on provenance is important in assuring sources of seed to give well-adapted, productive trees and in directing breeding of interracial and inter-specific hybrids toward adaptation to particular localities.
Nongrum, while highlighting the different regions from where samples were collected, said, “Reconnaissance survey of our study revealed 23 Tree bean habitats across the region. With dwindling population and ageing mother trees, we decided to study only on 7 rich density niches with two provenances each from Nagaland, Manipur, Mizoram and one from Meghalaya.” It is important to note that provenances were 10 km apart and their variation in altitudes was of a minimum 100 m within a state. From the marked 35 mother trees, altogether 175 fruits were sampled with 2,543 and 2,526 seeds collected each year, respectively.
The collection of samples marked the beginning of the arduous task of moving on with the experimentation and compiling the results. Following the collection of samples, in which mother trees were marked in all provenances and the fruits of Parkia were collected in spring season (early April to May), tree and fruit dimension were measured. Number of seeds per fruit was counted for all developed and the aborted seeds. Seeds were extracted from the pods and seed characteristics (seed weight, seed diameter, seed length and seed thickness) were determined. Germination was examined daily till there was no further record of germination. Seeds were considered germinated as early as the cotyledon emerges on the soil surface. Ungerminated seeds were retrieved to confirm death.
The data were analyzed statistically for mean, standard deviation and coefficient of variation. One-way analysis of variance was used to test the differences between group means. Pair-wise comparisons were made using Tukey’s post-hoc test.
There were marked differences in the phenotypic characteristics (an organism’s observable characteristics or traits) of the samples collected. “Many ecotypes of Parkia roxburghii must have developed during the process of evolution due to a vast distribution in different climatic and edaphic zones of this part of the region,” Nongrum said. He also observed that fully matured fruit vary widely in weight, length, width, angle of twist, pedicle length and number of seeds embedded from one variety to another and one provenance to the other.
The most interesting aspect was the marked differences in root and shoot length during seedling growth. Mean root length after one year of growth was longest in seedlings from Kezanglwa (Nagaland) while mean shoot length illustrated a non-linear rate of growth. The growth of seedlings was consistent except in month-6 coinciding winter when leaf fall caused a decline.
Nongrum said, “Although provenances differed significantly among themselves in parameters we studied, those are not remarkable to convince any genetic influence. Environmental factors too could play vital roles in variations.”
Nongrum is of the belief that people of Meghalaya need to be enlightened about the species to convince its domestication and consumption and has informed of making the publications available in the public domain.
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