种植密度对北方设施叶用甘薯茎尖、产量和效益的影响

为探索北方地区设施叶用甘薯适宜种植密度,兼顾采摘难易和效益,在留有采收空间的前提下,设置6个密度（12万、15万、18万、21万、24万和27万株/hm²）,研究其对叶用甘薯茎尖性状、采收产量和效益的影响。结果表明：与12万株/hm²处理相比,15万、18万、21万、24万和27万株/hm²处理下,总采收量分别显著增加14.9%、19.4%、25.7%、20.5%、16.4%,21万株/hm²处理的产量最高;产量的增加源于平均采收茎尖数的增加,其中单次采收茎尖数的增幅在采收前期和中期较大,采收前期茎尖产量的增幅高于后期。随着密度的增加,单个茎尖平均鲜重逐渐降低,主要源于采收茎尖基部茎粗的降低。各处理下叶用甘薯净效益均较12万株/hm²处理增加,以21万株/hm²处理的净效益最高,增幅达30.1%。综合考虑,为兼具采摘和生产功能,在设施留有30 cm采收空间的条件下,种植叶用甘薯推荐21万株/hm²的密度,3行为一生产单元,留出采收空档,参考株行距18 cm×17 cm。

Effect of Planting Density on Stem Tip,Yield and Planting Benefit of Facility Leaf-vegetable Sweet Potato in North China

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.