Abstract:
A field experiment was conducted at the B A College of Agriculture, Anand
Agricultural University, Anand (India)(22°35’N, 72°55’E; 45.1 m MSL)during rabi
(winter) season of 2003-2004 on a sandy loam soil to study the effect of row
orientation and row spacing on radiation interception, Leaf Area Index and Light
extinction coefficient in Wheat (Triticum aestivum L.) cv. GW-496 under two dates of
sowing. The PAR values in terms of incident/incoming PAR and transmitted PAR at
the field were measured after canopy development (i.e. 23 Days after sowing) at 10
day intervals at 0900-1000 h, 1200-1300 h and 1500-1600 h in a day with a Sun San
Canopy Analysis System (Delta-T Devices, UK). LAI was also measured directly by
the Sun Scan Canopy Analysis System at noon. The instantaneous values were
averaged for that day and were converted to MJm-2 day-1. Solar radiation was
recorded by a Pyranometer. The conversion of the daily solar radiation to PAR was
made by employing a 0.5 fraction. Narrow NS (North-South) rows in general
produced higher LAI throughout the growing season. NS row with narrow spacing
was the most effective treatment in relation to the accumulated IPAR values, although
the differences in the values corresponding to other treatments were not remarkable.
The fluctuations in extinction coefficient (k) values were less random in NS rows than
those corresponding ones for EW rows.
