Physiological And Biochemical Changes Of Potato Atlantic Tuber During Dormancy, Sprouting And Cold Storage

Potato (Solanum tuberosum L.) is the fourth staple food crop in the world, butunder room temperature potato tuber sprouts rapidly, which makes it unable to eat.The harvested tubers of potato are normally stored at low temperature to preventsprouting. But the increased reducing sugars (RS) caused the decrease of qualityduring low temperature storage. Therefor, the regulation of potato tuber dormancyand sprouting, as well as low temperature sweetening are key problems to be resolvedin potato production.This study takes the processing potato variety Atlantic as material, compared thecontents of endogenous phytohormones and polyamine of the apcial bud region oftuber and other regions of tuber, studied the changes of starch, soluble sugars andprotein, detected the activity changes of related enzymes and studied the effects onlow temperature sweetening under different storage measures. The results are asfollows:1 The contents of GA₁, GA₃, GA₄, IAA, Z and ABA in the apcial bud region oftuber were higher than those in other regions of tuber 40 days after harvesting(DAH).The change trends of the above phytohormones in both regions were alsodifferent. The contents of GA₁ and GA₄ decreased at 20 DAH and 40 DAH, and beganto increase after 40 DAH; the content of GA₃ began to increase at 20 DAH, thecontents of IAA and Z began to increase at 40 DAH; the content of ABA decreasedfrom 20 DAH to 55 DAH, and increased after 55 DAH. The changes ofphytohormones content in other regions of tuber had some differences with the apcialbud region of tuber. The content of GA₄ reduced from 20 DAH to 55 DAH, andincreased from 70 DAH to 85 DAH; the content of IAA reduced from 20 DAH to 55DAH, and slowly increased from 70 DAH to 85 DAH; the changes of Z content wasnot significant. The GA₄ was the major gibberellin in the apcial bud region of tuberand in other regions of tuber before sprouting, in the sproouting process, the GA₄content increased significantly in the apical bud region of tuber and in other regions oftuber, which indicated GA₄ plays an important role to break dormancy; while the GA₁content is the major gibberellin in the bud of after sprouting, which indicated GA₁plays an important role to bud growth.2 The putrescine and the spermidine contents decreased in other regions of tuberfrom 55 DAH to sprouting, the spermine content increased from 55 DAH to sprouting. But all the three polyamines contents in the apical bud region of tuberincreased from 70 DAH to sprouting, and the bud has the highest contents. At 70DAH, the putrescine content increased 1 time, the spermidine content increased 1.5times and the spermine content increased about 8 times. Exogenous polyaminesapplication showed that the exogenous polyamines had no obvious effect on potatodormancy, but promoted bud elongation growth and stem widening growth.3 From dormancy to sprouting, the starch content decreased gradually, and thesoluble sugars content increased gradually. Water soluble and alcohol soluble proteinhad a raise during later storge, and reached a highest content from 40 DAH. Theamylase activity increased from 40 DAH, amylophosphorylase activity increasedfrom 50 DAH, while the polyphenol oxidase activity decreased from 50 DAH. Theexogenous GA₃ increased the amylase and amylophosphorylase activities, speeded upthe starch decomposition and increased the soluble sugar content during the tuberstorge, and at the same time the exogenous GA₃ decreased the polyphenold oxidaseactivity, resulting in speeding up of potato sprouting.4 Fresh-keeping methods at the low temperature were studied and theoptimization measures to reduce the RS content during low temperature storage werescreened. The results showed that the formulation" 0.06% sodium phosphate+1% citricacid +1% chitosan" and formulation " 0.02% salicylic acid+1% citric acid +1%chitosan" decreased the RS content and increased the starch content during lowtemperature storage, which improved the storage quality of potato.