Effect of drought stress, nitrogen resources and plant density on some agro-physiological traits of Sunflower (Haysan variety) in the north of Golestan province

The present study was carried out to investigate the effect of drought stress, nitrogen resources and plant density on some agro-physiological traits of Sunflower (Haysan variety) in the north of Golestan province. This experiment was done as split plot factorial based on completely randomized design with 3 replication for two consecutive years and 27 treatments in 2017 and 2017. Irrigation factor in 3 levels: S1: rainfed, S2: one planting irrigation stage, S3: three irrigation (planting, flowering and seed filling) as main factor and nitrogen fertilizer resources in 3 levels: N1: 100% urea, N2: 50% urea and 50% nitroxin, N3: 100% nitroxin and plant density in 3 levels: D1: 50000 plants per hectare, D2: 75000 plants per hectare, D3: 100000 plants per hectare were considered as sub factor. The results showed that the highest mean of CGR was obtained in the S3N2 and N3D3 treatments with an average of 26.041 and 22.0300 g/m2, respectively. The highest plant height with values of 155.75 cm and 1252.89 cm was related to S3N2 and S3D3 treatments, respectively. The highest number of seeds per inflorescence belonged to S3N2 (285.68) the maximum 1000 seed weight with 29.27 g and 26.69 g were gained in S3D3 and N1D1 treatments. According to findings, the highest economic yield (192.88 kg/ha ) was conducted in irrigation at 3 stages, 50% urea fertilizer consumption + 50% nitroxin and 100,000 plant density per hectare.