Evaluation of direct seeding and transplanting in sugar beet for water productivity, yield and quality under different irrigation regimes and planting densities

Abstract

This study was conducted to investigate the effects of plant density, planting method and irrigation regime on water productivity and yield of sugar beet for two years during 2017 and 2018. The planted cultivar was Shokoofa with three irrigation levels: 100%, 75% and 50% of the full irrigation (1368 mm in 2017 and 1412 mm in 2018) as I100, I75 and I50, respectively, two planting methods: direct seeding (D) and transplanting (T) and four planting densities: 180,000, 135,000, 90,000, and 45,000 plants ha−1 as P180, P135, P90, and P45, respectively. Transplanting reduced applied water by about 24% and evapotranspiration about 25% as compared with direct seeding. Decreasing irrigation level, the root yield decreased about 7.4% in I75 to 26.4% in I50 as compared with I100. The difference between white sugar yield in I100 and I75 were not significant, but decreased significantly 17% in I50 as compared to I100 and I75. The root yield and white sugar yield in P90 treatment were higher than other treatments. The values of irrigation water productivity (WPIrrig) and white sugar yield water productivity (WPWSY) increased by 21.7% in I75 to 35.2% in I50 and 26.3% in I75 to 41.7% in I50, respectively as compared to I100. The difference between WPC in I75 and I50 were not significant and increased about 16.1% as compared to I100. Transplanting increased the root yield 7.7% and WPC, WPIrrig and WPWSY 45.7%, 44.7% and 47.7% as compared with direct seeding. The mean highest values of WPC, WPIrrig and WPWSY were 9.32, 9.95 and 1.39 kg m−3, respectively in P3 treatment. Therefore, in regions with scarce water resources, combination of transplanting method and plant density of 90,000 plant ha−1 under deficit irrigation in the level of 75% of full irrigation is suggested to obtain optimum sugar beet yield.