Boron is an essential micronutrient and plays a important role in fertilization and flowering process.
Synthesis
It has been known to be constituent of plants since 1857. Facilitating pollination and fruit set is considered to be the most important function of boron besides its role in the synthesis of amino acids and protein metabolism.
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Boron increases the translocation of sugar in plants and increases the rate of transport of sugars (which are produced by photosynthesis in mature plant leaves) to actively growing regions
It plays an important role in both structural and functional integrity of plasma membranes. Integrity and functionality of plasma membranes are ensured with adequate supply of boron.
Boron is involved in nitrogen fixation and it is required for growth and development of vascular tissues. It accelerates nitrogenous activity through effective nodule development for nitrogen fixation.
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Cole crops (those which grow well in temperate climate like cauliflower and cabbage) have high boron requirement and its deficit is high in acidic soils.
These crops develop crack, corky stem, petioles and midribs. In crops like Knol Khol (Kohl rabi), cracking will be seen and as a result these vegetables will not fetch a market value.
In cauliflower it appears as small water soaked areas in the centre of the curd. Later, the stem becomes hollow with soaked tissue surrounding the walls of the cavity.
Brown rot
In more advanced stage, pinkish or rusty brown areas develop on the surface of the curd and hence, it is also known as brown rot or red rot. Affected curd develops a bitter taste.
It can be controlled by application of borax or sodium tetra borate at 20 kg ha. In case of acute deficiency, foliar spray of 0.25 to 0.50 per cent solution of boric acid is advocated.
(J. Rajangam, associate prof and Head and D. Janaki, assiatant prof, soil science, Horticultural Research Station, TNAU, Kodaikanal, email: jrajangam2000@yahoo.com, mobile: 94438-89717, phone: 04542-240931.)