Plant density effect on growth and seed yield of wheat in saline soils and rainfedcondition

This experiment was carried out to investigate the effect of plant density on growth and seed yield of wheat (Kodasht cultivar) under saline soils and rainfed condition inAnbarolum region of Golestan province in 2008-09. An experiment was conducted in three fields with different salinities (6.73, 9.34 and 11.63 dS m^-1) based on randomized complete blocks design. Treatments were four plant densities (125, 250, 375 and 500 plant per m²)in three replications. The results showed that with increasing plant density leaf area index, stems number and fertile stems number per m² increased. The highest numbers of tillers per m² was produced at 250 plants per m², tiller number reduced with increasing plant density. The grain number per spike reduced from 16 numbers in 125plants per m² to 8.25 numbers per spike in 500 plants per m².Increasing plant density reduced thousand grain weights. In contrast, the highest dry matter was observed in the highest plant density. Increasing soil salinity reduced leaf area index, stems number, fertile stems and tillers number per m², grain number per spike and total dry matter ha^-1.The highest 1000 grain weight (38.42 gr) was observed in lowest soil salinity and reduced to 36.99 gr at 9.34 dS m^-1 and the highest salinity (11.63 gr) did not have significant effect on this trait. Interaction effect of salinity and plant density on fertile tillers number per m² showed that with increasing soil salinity probability of adequate growth of tiller for producing seed reduced; then, under the highest soil salinity even under low plant density tillers were not fertile. Seed yield increased with increasing plant density, but plant density role was not equal under saline condition. Increasing plant density from 375 to 500 plants per square meter under 6.73, 9.34 and 11.63 dS m^-1 caused 4.46, 7.70 and 10.51 percent increase in seed yield, respectively. Therefore, It is recommended that 375 plants per m²atsoil salinity about 7 dS m^-1 and less, and 500 plant m²in soils with about 9 dS m^-1 salinity and higher.