effect of salinity stress on growth analysis of isabgul, french psyllium and great plantain

Growth indices are useful for interpreting plant reaction to environmental factor. Using Growing Degree Days (GDD) for estimating the phonological growth stages is more valid instead of calendar time. In order to study effect of salinity on growth analysis in three different plantago species, a greenhouse experiment was conducted in Vali-e-Asr University of Rafsanjan in 2009. The study was carried out factorial experiment based on RCBD design with 4 replications to determine the influence of salinity (9, 15, 21 dS/m and control with distilled water) and three plantago species (Isabgul, French psyllium, Great plantain). Polynomial equations with the 88 to 98 distinction coefficient (R2) were known as the best indicator for interpreting of growth indices fluctuation to GDD. In all three species, the highest dry matter accumulation, leaf area, Crop growth rates (CGR) were observed in 900-1000 GDD at all salinity levels and in higher GDD, the decreeing trend of dry matter accumulation, leaf area and CGR were observed in all salinity levels. The lowest relative growth rate, crop growth rate, Leaf area ratio, dry matter accumulation were observed in 21 dS/m NaCl salinity. Results also indicated that maximum dry matter accumulation was observed in 800, 900 and 1100 degree day in Isabgul, French psyllium, Great plantain, respectively. No seed harvested from Isabgul and French psyllium in 21 dS/m. Among three species, great plantain could remain the highest leaf area consequently this species produced higher dry matter (0.4 gr per plant) and relative growth rate (0.06 g.g-1.10GDD-1) compared to other species. In general, among three species, great plantain was better species from a growth and seed yield point of view in salinity stress.