Effect of different root lengths for retaining freshness of hydroponic lettuce

Abstract

Harvesting with roots can help retain the freshness of hydroponic lettuce. And different root lengths may have different effects for freshness. To determine the optimal root length of hydroponic lettuce for retaining freshness, a root cutting and storage experiment was carried out to study some influenced factors of freshness such as changes in weight loss rate, color, and chlorophyll contents. Root lengths of samples were selected as five groups, i.e., 0 cm, 3 cm, 6 cm, 9 cm, and whole root length. Balance, chroma meter, and chlorophyll meter were used to measure the influenced indicators of different root lengths every other day for 15 days. Results showed that the relationship between the loss rate of chlorophyll content and the root length of hydroponic lettuce was not apparent. The chromatic aberration and the root length of hydroponic lettuce maintained a linear relationship. In the group of 0 cm, the chromatic aberration was 8.70 NBS that was maximum in the five groups. In the group of 9 cm, the chromatic aberration was 6.00 NBS that was minimal in the five groups. The relationship between the weight loss rate of hydroponic lettuce and the root length was linear. In the group of the whole root length, the weight loss rate of lettuces was 1.23% that was minimal in the five groups. It can be known that retaining the primary root or whole root of the hydroponic lettuce was beneficial for reducing the change in chromatic aberration, and increasing root length could reduce the weight loss rate of the lettuce. Therefore, considering the influence of the root length on the changes in weight loss rate, color, chlorophyll contents, and the hydroponic characteristics of lettuce, the optimal length of root retention for hydroponic lettuce was selected as 9 cm. • Different root lengths had an effect on retaining freshness of hydroponic lettuce. • Changes in weight loss rate, color, and chlorophyll contents were influenced factors. • Retaining the primary root or whole root could reduce change in chromatic aberration. • Increasing root length could reduce the weight loss rate of the hydroponic lettuce. • Different root lengths had no obvious effect on the loss rate of chlorophyll content.