Dieback Resistance Potential in Different Varieties of Shisham (Dalbergia sissoo Roxb.)
Abstract
Nine phenotypically different varieties of Shisham (Dalbergia sissoo Roxb.) were identified from Punjab University, Quaid-e-Azam Lahore, Pakistan and adjacent areas, on the basis of physical appearance of the plant, branching pattern, pod characters, leaf and leaflet size and shape, branching and leaf density and stem surface characteristics. On the basis of their relative resistance to dieback disease, the different varieties were named as Resistant 1, Susceptible 1‑4, Unspecified 1‑4. The Resistant 1 variety is characterized with dense, and long branches, which grow outward and downward forming a canopy. Generally plants do not attain much height. Leaves are large up to 16 cm in length, with four or five leaflets per leaf. Leaflets broad, globose or subglobose, young leaflets glaucous, mature leaflets glabrous, leaflet apex apiculate. Pods small, generally one rarely two seeded. Susceptible 1 and Susceptible 2 varieties were found to be highly susceptible to dieback showing 20% or more dieback incidence. These two varieties have been commonly cultivated in Punjab. Susceptible 3 and Susceptible 4 varieties were least susceptible showing dieback incidence not more than 2 %. The unspecified varieties 1 – 4 were named so because they did not show any disease symptoms but number of plants of these varieties was not large enough to decide their resistant potential. Shisham forestation can be revived by planting Resistant 1 and less susceptible varieties viz., Susceptible 3 and Susceptible 4 on suitable, well-drained sandy loam soils.
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