Abstract:

In order to clarify the suitable planting density of facility leaf-vegetable sweet potato in north China, taking both picking difficulty and planting benefit into account, 6 planting densities (120000, 150000, 180000, 210000, 240000, and 270000 plants/hm²) were set under the premise that there was space for harvesting, to study their effects on traits of stem tip, harvest yield and planting benefit. The results indicated that, compared with that under the density of 120000 plants/hm², the total yield significantly increased by 14.9%, 19.4%, 25.7%, 20.5% and 16.4% under the density of 150000, 180000, 210000, 240000, and 270000 plants/hm² , respectively, and the highest yield was achieved under 210000 plants/hm². The yield increase could be regarded as the result brought by the increase of average stem tip number. The increase of the stem tip number harvested per time in the early and middle harvest period was relatively big, thus making the yield of the two periods higher than that of the later period. As the density increased, the average fresh weight of single stem tip gradually decreased, mainly because the diameter of the base region of the harvested stem tip decreased. Compared with that under the planting density of 120000 plants/hm², the net benefit of leaf-vegetable sweet potato increased under all other planting densities, and the highest net benefit was found under the density of 210000 plants/hm², with an increase rate of 30.1%. In conclusion, for both picking and production function, by leaving the harvesting space of 30 cm, the density of 210000 plants/hm² is recommended for planting leaf-vegetable sweet potato, with 3 rows as one production unit and space between plants of 18 cm×17 cm.

Key words: leaf-vegetable sweet potato, planting density, harvest yield, traits of stem tip, planting benefit