The Effects Of Phosphorus Deficiency On Accumulation Of Carbohydrates And Root System Formation Of Potato Seedling

Phosphorus(P) plays an important role in growth and development of plants. Phosphorus deficiency restrictions the growth and development of plants and directly affects the quality and yield of plants. When plants encounter the low phosphorus stress environments, a series of adaptive changes were appeared in order to improve Pi absorption and utilization. Such reactions included the anthocyanin content, the chlorophyll content, the synthesis and transportation of carbohydrates, and the root system formation of plant. Finally, the characteristics of accumulation and distribution of carbohydrates were changed to adapt the phosphorus deficiency. The present study aimed to clarify the characteristics of accumulation and distribution of carbohydrates, root system formation of potato plantlet in vitro under different phosphorus levels. The results will provide the precise basic data for cultivate phosphorus deficiency tolerance in potato.Potato(Solanum tuberosum L.) cultivars “Atlantic” plantlets in vitro were used as material. The plantlet in vitro cultured on liquid MS medium with different phosphorus concentration. The anthocyanin content, Pi content, chlorophyll content, soluble sugar content, starch content, sucrose content, fructose content, reducing sugar content, root/shoot ratio, total root length, root surface area, root volume, average root diameter and lateral root number were determined after 16 d culture. The anthocyanin content, Pi content, chlorophyll content, accumulation and distribution of carbohydrates, formation of root system of potato plantlet in vitro were analyzed. The correlation between phosphorus concentration and soluble sugar content, starch content, sucrose content, reducing sugar content in shoots were analyzed, respectively. The results were as follows:Under non- phosphorus treated condition, the anthocyanin content of potato plantlet in vitro were highest, and decreased with the increasing of phosphorus concentration. The Pi content in shoots was highest under normal condition. With the increasing phosphorus concentration, the Pi content in shoots decreased first, and then increased, the Pi content in roots was increased. The chlorophyll content, chlorophyll a content were lowest under non- phosphorus treated condition. There were no significant change laws of chlorophyll content, chlorophyll a content and chlorophyll b content with the increasing of phosphorus concentration. Under non- phosphorus treated condition, the soluble sugar content, starch content, sucrose content in shoots were highest. With the increasing of phosphorus concentration, the soluble sugar content decreased first, and then increased, the starch content, sucrose content decreased. There were no significant change laws of fructose content in shoots. The reducing sugar content in shoots was lowest under normal conditions. With the increasing of phosphorus concentration, the reducing sugar content in shoots increased first, and then decreased, the soluble sugar content, starch content, sucrose content, reducing sugar content in roots decreased first, and then increased. The total root length, root surface area, root volume, lateral root number, root/shoot ratio of potato plantlet in vitro were lowest. With the increasing of phosphorus concentration, the above indexes were increased. The average root diameter was highest under nonphosphorus treated condition and decreased with the increasing phosphorus concentration. The correlation analysis indicated that there existed a strong negative linear relationship between phosphorus concentration and soluble sugar content, starch content, sucrose content, reducing sugar content in shoots, respectively. All above suggests that: under non- phosphorus treated condition, the root/shoot ratio decreased, the roots cannot absorb enough nutrition afford the growth and development of potato plantlet in vitro. Phosphorus deficiency affects the photosynthesis; the limited carbohydrates were used to root system formation, the root/shoot ratio increased, and more nutrition can afford the growth and development of potato plantlet in vitro. Under normal conditions, the anthocyanin content decreased and chlorophyll content increased, and there was a normal carbohydrate metabolism, the root system formation was promoted, which was beneficial to growth and development of potato plantlet in vitro.