Seed Morphology and Tetrazolium Quick Seed Viability Test of Malabar Neem (Melia dubia Cav.) Under Laboratory Condition

Melia dubia Cav. commonly known as Malabar Neem, is an economically important fast-growing indigenous multipurpose tree species of India. It has a wide range of applications from medicinal utilities such as treating pain, fever, and infections, to agricultural and industrial uses viz., fodder, seed oil, resin, fuel wood, timber and its wood being utilized in the paper, matchbox, and plywood industries. Malabar Neem generally is distributed in tropical and sub-tropical regions of India and introduced in many countries of South Africa, the Middle East, North and South America, Brazil, Bermuda, Argentina, Southern Europe, Southeast Australia, and Asia Pacific regions. Nevertheless, it is a most promising tree species which is highly suitable for agroforestry or farm forestry with a life cycle of 8 to 12 years that gaining economic importance both in domestic and global markets and plantations in degraded lands. Consequently, the demand of Melia seedlings among Indian farmers has been increased, however the poor seed viability and very low seed germination hampered the good quality nursery production and large-scale plantations. Before seed sowing in nursery, there is need to determine the actual seed viability and to know the required seed quantity of Melia to be sown in forest nursery. Therefore, the present research study was conducted at Dr. Y. S. Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh of India to study the seed morphology and seed viability testing protocol using tetrazolium (TZ) test. The seeds of Melia species stained with 0.5, 1.0, 1.5 and 2.0 % solution of TZ and incubated at 30°C temperature for 24 hours. The tetrazolium test performed with 100 seeds in 4 replications in CRD design and analyzed with OPSTAT statistical software. The length, width and weight of fruit, drupe and seed were recorded in the range of 9.40-12.97 mm, 6.55-9.70 mm & 2.84-2.99 g; 5.84-14.32 mm, 2.76-9.72 mm & 1.672-1.798 g; and 1.2-1.98 mm, 1.02-2.98 mm & 3.12-3.74 g, respectively. The colour of fruit was yellow with oval shape having smooth surface. The result of TZ test showed that the seeds of Malabar Neem soaked in 0.5 % tetrazolium solution at 30 °C temperature for 24 hours found to be the highest seed viability percentage (40.25 %) which is recommended as a quick seed viability protocol in M. dubia. Overall, the results of the present research study fulfilled all the gaps to test quick seed viability of a seed lot before seed sowing in nursery for accurate knowledge of the seed requirement in quantity for the purpose of quality seedling production in nursery.