| Abstract: In order to determine the effect of seeding amounts on the quantity and quality of sweet potato seedlings, 'Shangshu19' (S19) and 'Yanshu25' (Y25) were used as experimental materials, and four seeding amounts of 10, 15, 20, 25 kg/m2 were set in a way of horizontal arrangement, in which 25 kg/m2was the conventional seeding amount. The quantity, quality, growth characteristics of seedlings and internal environment conditions (temperature, humidity and light intensity) of sweet potato seedling
groups were studied. The results showed that the seedling quantity of 'S19' and 'Y25' increased at and then decreased with the increase of seeding amounts, the highest seeding amount treatments of 20 kg/m2 were 2 124 plants/m2 and 986 plants/m2, which were 107.4%, 19.1%, 10.1% and 100.4%, 45.4%, 8.6% higher than those of seeding amount treatments of 10, 15, 25 kg/m2, respectively. The net photosynthetic rate of leaf, shear force and tensile force of stem of 'Y25' were also the highest in seeding
amount treatment of 20 kg/m2, which increased by 16.54%, 25.4% and 44.5% compared with seeding amount treatment of 25 kg/m2, respectively. 'S19' and 'Y25' treated with 20 kg/m2 seeding amount were also significantly higher than those of 25 kg/m2 seeding amount treatment, such as the strength-weakness ratio of seedlings, mechanical force of stems, lignin content of stems, dry-matter rate of leaves, petioles and stems. The light intensity of 'S19' and 'Y25' seedlings decreased with the increase of seeding amounts, and the seeding amount treatment of 20 kg/m2 increased by 20.1% and 18.2% compared with 25 kg/m2seeding amount, respectively. The relative humidity of seeding amount treatment of 20 kg/m2 decreased by 12.2% and 4.7% compared with 25 kg/m2 seeding amount, respectively. The temperature of seedling population
decreased first and then increased with the increase of seeding amounts, and the temperature of of 20 kg/m2seeding amount of 'S19' decreased significantly by 5.1% compared with that of 25 kg/m2 seeding amount. In summary, the appropriate seeding amounts could form a reasonable population structure of sweet potato seedlings, improve the microclimate within the population, advance the photosynthetic performance and stem mechanical force of sweet potato seedlings, promote dry-matter accumulation of seedlings, and significantly raise the quantity and quality of sweet potato seedlings. Under the condition of horizontal row, the optimum seeding amounts for the purpose of seedling quantity was 20 kg/m2. |