Effect of boron stress on growth, soluble protein and enzyme activities in flue-cured tobacco
2009
Anuradha, M. | Rao, K.N. | Sivaraju, K. | Krishnamurthy, V.
Sand culture experiment was conducted using Hoagland solution to study the effect of deficient and excess levels of boron (B) on the growth, protein pattern and enzyme activities in flue cured tobacco (Nicotiana tabacum L). Boron deficiency resulted in stunted growth, drastic reduction in internodal length and progressive death of shoot apex followed by the growth of lateral shoots. The lateral shoots were also deformed and died subsequently. The leaves of boron deficient plants were thick and brittle. The boron content of the leaf lamina of the deficient plants ranged from 6 to 16 ppm. The plants supplied with excess of boron showed yellowing of leaf tips followed by progressive necrosis. Necrotic symptoms spread progressively towards the leaf margins and midrib. When the symptoms were severe, the bottom leaves dropped prematurely. The boron content of the leaves showing severe symptoms of toxicity was 1950 ppm. Leaf soluble protein content decreased in both deficient and excess levels of boron. The activity o!- peroxidase, polyphenol oxidase and phenylalanine ammonia lyase increased by 29, 18 and 14% respectively, in B deficiency whereas, the activity of acid phosphatase decreased by 33%. In excess boron, the activity of peroxidase and acid phosphatase increased.
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