Effects of Planting Density and Harvest Time on Main Agronomic Traits and Flower and Leaf Yield of Industrial Hemp"Yunma 7"
In order to find out the best planting density and harvest period of industrial hemp for flowers and leaves in Yunnan,a randomized field block trial was conducted in Zhanyi District,Qujing City,Yunnan Province in 2019 and 2020,respectively,using a leading variety Yunma 7 in Yunnan as the material.Four planting densities(5000,10 000,20 000 and 30 000 plants/hm2)and four harvest periods(140,150,160 and 170 days)were set in both years.Plant height,stem diameter,flower and leaf yield,stem yield and CBD content were measured during the harvest period.When harvested at 170 days,the plant height reached the maximum at the density of 20 000 plants/hm2,which were 346.8 cm and 267.1 cm in respective two years,while the stem diameter reached the maximum at the density of 5000 plants/hm2,which were 44.3 mm and 49.3 mm,respectively.In 2019,the maximum yield of flow-er and leaf was 3375 kg/hm2 at harvest period of 140 days and density of 30 000 plants/hm2.So that was 5247 kg/hm2 in 2020 when harvest at 170 days and 20 000 plants/hm2 density.In 2019,the stem yield and total aboveground yield reached the maximum of 7560 kg/hm2 and 11 014 kg/hm2 respectively under the condition of 150 days harvest and 30 000 plants/hm2.In 2020,the stem yield and total aboveground yield reached the maximum of 5602 kg/hm2(20 000 plants/hm2)and 11 001 kg/hm2(30 000 plants/hm2)when harvest at 170 days.The maximum CBD content of hemp in this two year were 1.2%and 2.4%un-der the conditions of 160 d harvest and 10 000 plants/hm2 density.The flower and leaf yield and CBD content of industrial hemp were affected by the cultivation density and harvest time.The important culti-vation measure for Yunma 7 to obtain highest yield were cultivation density of 30 000 plants/hm2 and the harvest time of 170 days.The key factor to obtain highest CBD content were 160 days harvest and 10 000 plants/hm2 density.
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