Effects of night low temperature on carbohydrate content in different organs along assimilate transport path of melon.

Under different night low temperature,changes of carbohydrate composition and content in different organ along melon assimilate transport path were studied by HPLC.The results indicated that carbohydrate content is different at different organ along the transport route from source to sink.Glucose was the highest and galactinol,raffinose and stachyose were the lowest in contents in leaf,with fructose and sucrose standing in the medium.A lot of sucrose,raffinose and stachyose were accumulated in vascular bundle,while there lied much fructose and glucose as well as little galactinol.Meanwhile,glucose and fructose,representing the predominant sugar were nearly equal in amount,with galactinol,raffinose and stachyose being present in trace quantities.In addition,the treatment of 9℃ in night,the content of sugar was increased obviously compare to control in leaf and vascular bundle,however,the content of sugar in fruit was reduced in evidence.However,12℃ in night had no effect on carbohydrate content at different parts along the transport route from source to sink.These results suggested that 9℃ in night caused carbohydrate content to increase in leaf,and inhibited the transport of sugar.As a result,the content of sugar in fruit was affected seriously.Furthermore,9℃ in night may have a positive effect on the hydrolyze of stachyose in fruit vascular bundle.