Assessment of radiation interception in a modified microenvironment and its relationships with biophysical parameters
2012
Adak, Tarun | Kumar, Gopal | Chakravarty, N.V.K.
Changes in radiation interception at critical phenological stages influence dry matter production and radiation use efficiency of oilseed Brassica crops. Henceforth, a field experiment was conducted during two consecutive winter seasons of 2005–06 and 2006–07 on a sandy clay loam soils at research farm of Indian Agricultural Research Institute, New Delhi representing semi-arid climatic condition to evaluate radiation-crop interactions in mustard cultivars under debranching conditions using line quantum sensor. Radiation penetration, interception and biophysical parameters like leaf area index and dry biomass were studied periodically. Logarithmic trend of radiation penetration was observed within the canopy (R ² = 0.74** and 0.62** from top to bottom and mid to bottom of the canopy, respectively). Best fit second order polynomial regression analysis measured about 53–66% variations in Intercepted PAR (IPAR) at different phenological stages of the crop. Linear regression analysis inferred that cumulative IPAR could successfully be used in predicting biophysical parameters like leaf area index (LAI) and dry matter (DM) production. It was inferred that cumulated IPAR could explain variation in LAI and DM of the order 54–72% and 85–91%, respectively. The radiation use efficiency was observed to be varied from to 4.5 g MJ ⁻¹ across different treatments with the mean values ranged between to 1.69 g MJ ⁻¹. The study showed that line quantum sensor based techniques for radiation study could be used to estimate relevant biophysical parameters, their relationship with radiation and radiation utilization capacity of oilseed crop and thereby useful in developing dynamic crop simulation model. The regression models developed might be useful in other related Brassica spp for its quantification of variability of IPAR and biophysical parameters.
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