Author(s): D. FANGZAUVA, M. K. NANDA AND P. K. CHAKRABORTY

Abstract: Extinction coefficient is a measure of attenuation of radiation within a crop canopy which solely depends on foliage volume of a crop. Field experiment on pigeon pea was carried out during winter season of 2004-05 at Kalyani, BCKV (22°30\' N and 89° E) to find out the effect of plant height and LAI on the extinction coefficient of crop. The crop was sown on 25th October, 2004, with two spacings viz. 5cm x 30cm and 30cm x 45cm. The total solar radiation and photosynthetic active radiation were measured on 31th December 2004, 4th February and 15th March 2005 with LICOR Photoradiometer. The extinction coefficients, calculated using Beer\'s Law, increased with the increase in plant height and LAI with higher attenuation of radiation within the canopy. Crops grown with wider spacing was associated with higher attenuation of radiation and extinction coefficient and lesser yield and sunlit leaf than those obtained from crops grown with narrow spacing.

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