تاثير كود نيتروژن و تراكم گياهي بر جذب وكارآيي مصرف نور در دو رقم كلزاي بهاره

Influence of nitrogen and plant density on light absorption and radiation use efficiency in two spring rapeseed cultivars

In order to study the effects of nitrogen and plant density on light absorption and radiation use efficiency (RUE) in two spring rapeseed cultivars, a split plot factorial experiment based on randomized complete block design with four replications was conducted in 2005 in research farm of Ferdowsi University of Mashhad-Iran. The treatments included two levels of urea application (100 and 150 kg/ha) as main plots and subplots were combination of plant density (60, 80, and 100 plant/m2) and rapeseed cultivars (Hyola308 and Option500, early and medium maturing cultivars, respectively). Results indicated that treatments influenced significantly on light absorption rate and RUE. Increasing nitrogen application rate, from measured factors, only LAI and RUE were significantly influenced. Hyola308 cultivar had higher RUE, biological and grain yield and oil yield compared to Option500. The only preference of Option500 cultivar was 1000 seed weight. Dry matter production and RUE was significantly higher in 80 plant/ m2 compared to other plant densities. Increased dry matter in this density was due to higher light absorption and consequently increased RUE. Among all determined parameters, LAI was significantly influenced, and highest LAI observed with Option500 cultivar, which occurred in 100 plant/ m2 density and 150 kg/ha urea application. Among yield components, only pod number per plant was affected by plant density, as highest number of pods observed in 60 plant/m2 treatment. None of the treatments influenced seed oil percentage.