Abstract
Crop growth and development is imperative to study the plant behaviour under a set of environmental conditions. Genotypes may respond differently under same conditions according to their genetic makeup, photosynthesis and assimilation potential. Growth and development of safflower genotypes was studied through field experiments executed at PMAS-Arid Agriculture University, Rawalpindi during 2006-2007 and 2007-2008. Eight safflower genotypes Thori-78, SAF-30, SAF-31, SAF-32, Leed-00, SAF-128, SAF-129 and SAF-130 were evaluated for growth analysis viz. leaf area index (LAI), crop growth rate (CGR) and net assimilation rate carried out at 21 days interval after germination till maturity during both years. Significant differences were observed for the growth attributes among genotypes at different sampling intervals. LAI, CGR and NAR followed sigmoid pattern consistently increasing at the start of observation, attaining peaks and decreased thereafter till maturity. The decline in growth after zenith may be due to increased aging of older leaves and shifting of crop to reproductive stage. Similarly, genotypes differed statistically for biomass and seed yield. Environmental variables like rainfall and temperature influenced ontogenetic and developmental pattern of genotypes. Positive relationship concludes heavy dependence of biomass and yields with growth parameters. (C) 2015 Friends Science Publishers