Can you summarize the findings of the study on the effect of environment and time of planting on yacon root production and quality?: Douglas, J.A., Follett, J.M., Douglas, M.H., Deo, B., Scheffer, J.J.C., …, Manley-Harris, M. (2007). Effect of environment and time of planting on the production and quality of yacon (Smallanthus sonchifolius) storage roots. New Zealand Journal of Crop and Horticultural Science, 35(1), 107-116.
The tuberous root yields of yacon (Smallanthus sonchifolius) were compared from field trials planted in September, October, and November at four sites (Pukekohe, Hamilton, Lincoln, Mosgiel) across New Zealand. The September plantings gave the highest yields at all sites, with the October plantings giving 17% less yield and the November plantings 61% less. The September planting at Hamilton produced the highest yield of 90 t/ha, Pukekohe 64 t/ha, Lincoln 22 t/ha, and Mosgiel 15 t/ha. Regression analysis established a strong positive relationship between dry root yield and accumulated growing degree days (GDD) below 10°C calculated for base temperatures 0, 6, and 8°C (R² = 0.87–0.88). Regression analysis R² values declined above 10°C. Dry root yields were high where heat accumulation was at least 1800 GDD8 for the growing season with c. 1 t/ha of dried roots being produced for every additional 100 GDD8 above 1200 degree days. This relationship helps to identify suitable production environments for yacon. Best root production also needs an undefined level of cool temperatures as at the warmest site crown production was favoured. Total fructo‐oligosaccharide (FOS) content of the yacon roots varied from 48.2% to 67.5%. November yacon had the lowest FOS content and conversely the highest content of non‐FOS carbohydrates.
user
Sure, I can provide a summary of the study's findings. Douglas et al. (2007) conducted field trials with yacon (Smallanthus sonchifolius) in New Zealand, comparing the effect of three planting times (September, October, and November) and four locations (Pukekohe, Hamilton, Lincoln, Mosgiel) on root yield and quality. They found that the September plantings resulted in the highest yields, with October plantings yielding 17% less and November plantings yielding 61% less. The September planting at Hamilton had the highest yield of 90 t/ha, followed by 64 t/ha at Pukekohe, 22 t/ha at Lincoln, and 15 t/ha at Mosgiel. The study established a strong positive relationship between dry root yield and accumulated growing degree days (GDD) below 10°C, with a higher yield associated with at least 1800 GDD8 for the growing season. However, FOS content in the roots varied between 48.2% and 67.5%, with November plantings having the lowest FOS content and the highest content of non-FOS carbohydrates. It was found that root production required an undefined level of cool temperatures since crown production was favored at the warmer site. The relationship between growing degree days and yacon root yield helps identify suitable locations for yacon production.
assistant
Can you summarize the findings of the study on the effect of environment and time of planting on yacon root production and quality?: Douglas, J.A., Follett, J.M., Douglas, M.H., Deo, B., Scheffer, J.J.C., …, Manley-Harris, M. (2007). Effect of environment and time of planting on the production and quality of yacon (Smallanthus sonchifolius) storage roots. New Zealand Journal of Crop and Horticultural Science, 35(1), 107-116.
The tuberous root yields of yacon (Smallanthus sonchifolius) were compared from field trials planted in September, October, and November at four sites (Pukekohe, Hamilton, Lincoln, Mosgiel) across New Zealand. The September plantings gave the highest yields at all sites, with the October plantings giving 17% less yield and the November plantings 61% less. The September planting at Hamilton produced the highest yield of 90 t/ha, Pukekohe 64 t/ha, Lincoln 22 t/ha, and Mosgiel 15 t/ha. Regression analysis established a strong positive relationship between dry root yield and accumulated growing degree days (GDD) below 10°C calculated for base temperatures 0, 6, and 8°C (R² = 0.87–0.88). Regression analysis R² values declined above 10°C. Dry root yields were high where heat accumulation was at least 1800 GDD8 for the growing season with c. 1 t/ha of dried roots being produced for every additional 100 GDD8 above 1200 degree days. This relationship helps to identify suitable production environments for yacon. Best root production also needs an undefined level of cool temperatures as at the warmest site crown production was favoured. Total fructo‐oligosaccharide (FOS) content of the yacon roots varied from 48.2% to 67.5%. November yacon had the lowest FOS content and conversely the highest content of non‐FOS carbohydrates.
user
The study by Douglas et al. (2007) investigated the impact of environment and planting time on the production and quality of yacon (Smallanthus sonchifolius) storage roots. The research was conducted across four sites in New Zealand, with planting done in September, October, and November.

The findings indicated that September plantings yielded the highest production at all sites, with October and November plantings resulting in 17% and 61% less yield, respectively. The highest yield was observed in the September planting at Hamilton (90 t/ha), followed by Pukekohe (64 t/ha), Lincoln (22 t/ha), and Mosgiel (15 t/ha).

The study also found a strong positive correlation between dry root yield and accumulated growing degree days (GDD) below 10°C, calculated for base temperatures 0, 6, and 8°C (R² = 0.87–0.88). The regression analysis showed a decline in R² values above 10°C. Dry root yields were highest when heat accumulation was at least 1800 GDD8 for the growing season, with approximately 1 t/ha of dried roots produced for every additional 100 GDD8 above 1200 degree days.

The quality of the yacon roots was also affected by the planting time. The total fructo‐oligosaccharide (FOS) content varied from 48.2% to 67.5%, with November yacon roots having the lowest FOS content and the highest content of non‐FOS carbohydrates.

In conclusion, the study suggests that the best environment for yacon root production is one with an accumulation of at least 1800 GDD8 for the growing season, and planting should ideally be done in September for optimal yield and quality. However, a certain level of cool temperatures is also necessary, as warmer temperatures tend to favor crown production over root production.
assistant