Physiological characteristics of dalbergia melanoxylon and dalbergia sissoo seeds and seedlings

This work is a study on physiological characteristics of Dalbergia melanoxylon and Dalbergia sissoo seeds and seedlings. Objectives of this work were to study physiological characteristics of the above mentioned species, and to explore methods of seed dormancy breaking. The study aimed also to compare between the indigenous species D.melanoxylon and exotic species D.sissoo in seeds and seedlings morphology and growth in relation to irrigation regimes in the nursery. Seed physical and physiological characteristics were explored through the determination of seed soundness, damaged and abortive seeds, purity percentage, number of seeds per kilogram, seed size and shape, seed moisture content percentage, viability percentage, germination rate, and percentage, and the phenomenon of seed dormancy. Different treatments were applied to break seed dormancy. The presence of fruit coat inhibitors was studied. Seed essential elements were determin ed. Seed behaviour (germination, viability and moisture content) was followed every 6 months for 18 months in the normal and cool store. A nursery experiment was conducted with three irrigation regimes were applied for three months. Seedling morphology and growth parameters were studied. The study revealed that more than 70% of D. melanoxylon seeds were abortive or damaged by insects when collected. Seed characteristics of the both D.melanoxylon and D.sissoo were found to be more or less similar. Extraction of seeds from the pods, sulphuric acid for one minute and dewinging were found to be the best treatments for dormancy breaking. Seeds were found to have a combined external dormancy of chemical and physical type. The study revealed that seeds kept in the normal store and the cool store for 18 months had more or less the same germination behaviour. Seed viability was kept high in both stores through out storage period. Seedlings growth showed no significant differences du r ing first two months of irrigation. Thereafter, D.sissoo was the best in growth parameters followed by D. melanoxylon from South Kordofan. Seedling survival rate was affected after the first month under irrigation regimes, after that a 100% survival rate was observed. The study recommended that the seed of D. melanoxylon from South Kordofan could be stored normally at room temperature (25-30°c) for 18 month. The study recommended the use of the irrigation regime once a week or once every two weeks during the rainy season and twice a week or once a week during the dry period