Ameliorative Role of Boron on Morpho-physiological Characters of Mandarin Orange Seedlings under Aluminium Stress Condition

Darjeeling mandarin orange is well known for its unique and delicious taste. It is also considered as one of the major cash crop of Darjeeling hills. But in recent past, the production has been declined drastically due to some of the biotic and abiotic factors. Acidic soils are mainly confined in this region which has a complex interaction of growth limiting factors that can restricts growth by inducing stress on plants through triggering aluminium stress and micronutrient Deficiency. This has resulted in declination in production and quality of mandarin orange grown in foothills of Darjeeling. Since boron is known to act as ameliorative role under aluminium toxicity, the present study was investigated to understand the effect of boron in mandarin orange seedlings grown under aluminium stress condition. Seedlings of Darjeeling mandarin orange were fertilized with Hoagland solution containing four levels of boron (i.e, 0µM, 5µM, 10µM and 25µM H3BO3) and two level of Aluminium (i.e., 0µM and 1200µM AlCl3.6 H2O) up to 22 weeks. Seedlings without boron and aluminium was treated as the control. Aluminium at higher concentration severely hinder physiological changes in terms of shoot length, leave numbers, leaf area, fresh shoot, root weight, chlorophyll content and carotenoid of mandarin seedlings. However, the application of boron improved the physiological attributes under higher concentration of aluminium. Furthermore, application of boron concentration at 10µM proved to be better treatment for mandarin seedlings grown under aluminium stress condition.