Magnolia punduana Hk. f. & Th. (syn. Michelia punduana) is a threatened tree species restricted to northeastern India. The seeds remain dormant for 6 months after dispersal. Seed development and breaking of dormancy was investigated in the present study. Physical treatments such as water (cold, hot, and boiling) and acid and manual scarification proved ineffective in breaking dormancy. Matured seeds had linear and underdeveloped embryos at the time of dispersal with an embryo to seed length (E:S) ratio of 0.13. Germinating seeds showed a significant increase in the embryo length with an E:S ratio of 0.36. Cold stratification (CS) at 5 °C effectively broke dormancy. The embryo grew significantly after CS, indicating the presence of “non-deep simple” morphophysiological dormancy (MPD). Application of GA3 had a significant effect on germination and the lowest germination time with the shortest T50 was observed in seeds treated with 3000 mg·L−1 GA3. KNO3 did not have an influence on breaking dormancy except in combination with GA3, which increased the germination percentage significantly. CS for 90 days and GA3 (3000 mg·L−1) at 25 °C resulted in optimum germination. In the test for viability, seeds stored at 5 °C showed highest viability of 66.66% after 180 days.
Introduction: A strong positive 'abundance and habitat-suitability' relationship is crucial for conservation of species. Nevertheless, anthropogenic alteration of natural landscapes leading to land use and land cover change, habitat loss, and species extinctions (may) have putatively disturbed this relationship. Hence, it is important to study the nature of the relationship in such human influenced landscapes. Methods: In this study, we endeavored to understand the consistency of the relationship in the fragmented natural landscapes in the Khasi, Garo, and Jaintia hills of Meghalaya in northeast India, with Adinandra griffithii (an endangered endemic tree) as a model species. We reconstructed the distribution of its suitable habitats as a function of the remotely sensed vegetation phenology (i.e., EVI data), using point occurrence data and ecological niche modeling (ENM) tool. Estimation of the abundance and habitat characterization was done through field surveys following standard methods. Results: The study revealed that remotely sensed landscape-level vegetation phenology could effectively discriminate the suitable and unsuitable habitats of threatened species. Linear regression model showed a weak positive correlation between abundance and predicted habitat suitability for adult trees indicating (plausible) deterioration in the relationship. However, sapling and seedling populations did not show a precise trend in this respect. Field-based studies revealed that removal of the species from the suitable habitats because of anthropogenic disturbances possibly weakened the abundance-suitability relationship. Conclusions: The findings of the study enjoin the need for re-establishment of the species in the suitable areas for its conservation and perpetuation.
Background: Elaeocarpus prunifolius Wall. ex Müll. Berol. is a threatened tree species of northeastern India. The present study was undertaken to investigate the type of dormancy prevailing in seeds of E. prunifolius, explore seed dormancy breaking techniques and assess seedling fitness. Methods: Ripe fruits of E. prunifolius were harvested from Jaintia hills, and seeds were subjected to various physical, manual and chemical treatments. The effect of plant growth regulators, viz gibberellic acid (GA 3) and potassium nitrate (KNO 3), were tested. Seedling vigour and survival based on seed weight were examined. Results: Germination took 6 months to initiate after seed dispersal and natural germination percentage of fresh seeds was 24%. Physical pre-germination treatments such as surface and acid scarification failed to overcome dormancy. Cracked seeds promoted germination (46%) with a mean germination time of 146 days (time to 50% germination, T 50 = 144 days). Among the GA 3 treatments, split seeds treated with GA 3 (3000 mg/L −1) yielded the highest germination (24%) with a T 50 of 55 days whereas KNO 3 did not promote germination. A combination of GA 3 and KNO 3 , however, increased the germination to 31%. Between the seed weight classes, the highest percentage of germination was observed in heavy seeds (25%) and the lowest in light seeds (20%). There was no significant variation between seed weight and germination time (p > 0.05). Seed weight had a significant effect on the shoot height, number of leaves and dry weight of seedlings (p < 0.05). Conclusion: Based on the seed tests, E. prunifolius seeds exhibits 'combined' dormancy (physical and physiological) as splitting seed coat and application of GA 3 effectively broke dormancy. Splitting the seed coat is a cost-effective method for accelerating germination of seeds. Heavyweight seeds produced better performing seedlings compared to their counterparts which may be viewed as an important reproductive strategy of the species.
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