Volume 82, Issue 6
December 1975, pages 205-229
pp 205-210 December 1975
pp 211-217 December 1975
The present study aims at localization of various chemical substances, namely, polysaccharides, DNA, RNA, proteins, ascorbic acid (AA), lipids and reducing sugars in the tissue-sections (fixed and fresh materials) of scutellum and endosperm of the seedlings—until 3 days after germination. The plants investigated are:Triticum durum, Pennisetum typhoideum, Panicum miliaceum andSetaria italica. Contributory role of these substances in these tissues is assessed.
Scutellum is generally rich in starch, RNA, DNA, proteins, lipids, AA and low in reducing sugars. Similarly, epithelial layer is also rich in these substances excepting reducing sugars and the PAS-positive bodies therein are not starch. Endosperm stores large quantity of starch and lipids, and rarely a few AA bodies. The aleurone layer resembles the epithelial layer in all its components.
It is observed that in Gramineae the scutellum and endosperm are essentially storage tissues meant for the developing seedlings. The storage substances are translocated into the latter through scutellum and the enzymes, which are secreted in the epithelial and aleurone layers, assist the scutellum in this function. Azure B-positive RNA bodies of the scutellum and epithelial layer are unusual.
pp 218-220 December 1975
Polygala raoi R. N. Ban. et L. K. Ban. a new species collected from Vivekanandapuram, Kanya Kumari District, Tamil Nadu, is described here.
pp 221-229 December 1975
Three types of glass-fibre and one membrane filter were compared for the amount of radioactivity retained under conditions typical of primary productivity experiments. All filters showed comparable results in terms of total radioactivity retained. It did not matter whether filters were removed from the filtration apparatus before or after the vacuum had been taken off. Filtration times of membrane filters were 3–6 times longer than those of glass-fibre filters. All filters tended to significantly increase the background levels of the scintillation fluor as a result of passage of water through them followed by fuming with concentrated HCl.