Evaluation of Yield of Cotton (Gossypium hirsutum) Cultivars in Ultra Narrow Row (UNR) Spacing at Two Planting Dates

In order to investigate the effects of reduced row spacing from usual 75 cm to 25 cm (UNR), an experiment has been conducted in two locations: Davarabad agricultural research station (Semnan Province) and Varamin Central Agricultural Research Station. The experimental design is RCBD laid out in split plots with three replications. The main plots are the planting dates (May 22 and Jun 5, 2020) and five cultivars, i.e. Khorshid, Kashmar, Sajedi, Hekmat, and Khordad serve as the sub plots. The results show that location effect on vegetative and reproductive attributes has been significant. UNR boosts the yield in Aradan, but in Varamin region, this planting method, not only has failed to increase the yield, but has reduced it significantly. This is due to reducing the boll number as a result of rank growth of plants in UNR system. Reduction of row spaces from 75 to 25 cm enhances the number of monopodials, sympodials, and plant height. In Varamin, plant height of all cultivars are higher than 119 cm. the highest yield in this region obtained from Khordad as Control (3886 kg seed ha -1). The highest yield in Aradan, obtained from Khorshid (5702.5 kg seed ha -1) in UNR system. This shows that the UNR planting of zero type varieties is more adabtable for Garmsar condition than that of Varamin.