Wood anatomy and heartwood formation in Neem (Azadirachta indica A. Juss.)

Abstract

The wood of Azadirachta indica is diffuse porous. Axial parenchyma is paratracheal banded or vasicentric. Rays are uniseriate to multiseriate and heterocellular with procumbent and upright cells. There is a strong negative correlation between vessel member length and diameter. The vulnerability and mesomorphic values are different in two trees of almost the same age growing in the same locality. The vessel member wall has spiral thickenings on its inner surface. Axial and ray parenchyma cells and sometimes vessels and fibres of the heartwood show the presence of extractives. The necrobiosis of the parenchyma cells occurs at the heartwood boundary. Senescence and death of parenchyma cells are associated with depletion of starch grains and accumulation of extractives. There is a climacteric rise in succinate dehydrogenase and acid phosphatase activities at the sapwood‐heartwood interface which may be associated with heartwood formation. Peroxidase activity is greater near the cambial zone, indicating its probable role in lignification.

Elicitors Modulate Young Sandalwood (Santalum album L.) Growth, Heartwood Formation, and Concrete Oil Synthesis

“…In some tree species, the generation of yellow or brown extracts and the appearance of a fragrant scent is a simpler and more convenient way to determine if heartwood has formed rather than measuring heartwood formation using programmed cell death or specific enzyme activity [ 30 , 31 , 32 , 33 ]. In BA-treated trees, the change in color and emission of a scent in wood chips demonstrated that BA is an effective chemical elicitor for inducing heartwood in 5-year-old sandalwood trees ( Figure 4 a,b).…”

Formation of heartwood substances in the stemwood of Robinia pseudoacacia L. II. Distribution of nonstructural carbohydrates and wood extractives across the trunk

“…Small amounts of sugars like mannose and arabinose in the heartwood of Scots pine might originate from the breakdown of hemicelluloses during heartwood formation (Fischer and H611 1992;Saranp~i~i and Hrll 1989). Numerous light and electron microscopic studies revealed that during sapwood-heartwood transformation storage material, mainly starch, is consumed or withdrawn (Datta and Kumar 1987;Kumar and Datta 1989;Nair 1988;Nobuchi et al 1982Nobuchi et al , 1984Nobuchi et al , 1987a.…”