Effects Of Different Plant Growth Regulators On The Dormancy And Germination Of Potato Tubers During Storage Period

Potato tuber is the propagative organ and nutritive organ,potato tuber storage is one of the important links in the potato industry chain.In the actual production,in order to satisfy the demand of different sowing dates and to keep high rate of emergence and growth potential in seed potato,it always requires prolonging or shortening the dormancy stage to guarantee the field emergence.Meanwhile,when potatoes are used as food,the dormancy period should be prolonged as long as possible to keep the potatoes fresh.Therefore,the regulation of dormancy is very essential in the production of potato.In this research,the mid-to-long term dormancy potato cultivar "Chuanyu 117" and the short term dormancy cultivar "Favorita" were used as experimental materials,the potato tubers were dipped in three different plant growth regulators aqueous solutions:GA3(gibberellin A3,GA3),CIPC(chlorpropham,CIPC)and ABA(abscisic acid,ABA),for 30 minutes,respectively.To study the effect of different plant growth regulators on dynamic germination,the main nutrients content change of whole potato tubers in different storage period,the different enzymes activities of tuber flesh and bud base from different dormancy potato cultivars,and endogenous hormones content change of different parts of tubers during storage.The main results of the research are as bellow:1.The result showed that the 4 mg/L of ABA could delay the germination of the potato tuber significantly.The germination period delayed for 5 days,the dormancy amplitude was shortrned by 9 days,and the fresh weight loss ratio was reduced by 19.06%,compared with CK,respectively.Meanwhile,the shoot length grew quickly after germination.The germination series were gradually decreasing with the increasing of the ABA concentration.Therefore,the 4 mg/L of ABA was the appropriate working concentration to inhibit potato germination.2.The treatment of 15 mg/L GA3 could break the potato dormancy in advance,shorten the germination period,dormancy period,dormancy strength and dormancy amplitude,as well as improve the germination series.The treatment of 4 mg/L ABA could prolong the dormancy,shorten the dormancy amplitude and reduce the germination series to a certain extent.There was no germination of the tubers treated by 1.5 g/L CIPC during the observation period.The GA3,ABA and CIPC treatments worked more efficient to the mid-long term potato cultivar "Chuanyu 117" when compared with the short term potato cultivar "Favorita".Meanwhile,the effect in 2014 was better than that in 2015,especially to the "Chuanyu 117".In this text,the logistic function or equation of linear regression between the germination dynamic,shoot growth(shoot length and shoot diameter)and the number of days after treatment were established,thus the quantitative relation btween the indexes were clearing.3.The fresh weight loss ratio gradient of "Favorita" was higher than that of "Chuanyu 117"during dormancy breaking process under different growth regulators treatments.In 2014,the fresh weight loss ratios of GA3 treatment were the maximum among all treatments during the whole storage period.While in 2015,the fresh weight loss ratio rangeabilities of"Chuanyu 117" and "Favorita" from the first day to the 56th and 42th day after treated by GA3 were the maximum.The ABA and CIPC could reduce the weight loss.The starch contents of potatoes treated with GA3,ABA and CIPC for 12 weeks reduced by 13.36%,11.30%and 5.93%,respectively;while the soluble sugar contents reduced by 48.3%,58.9%and 56.1%,respectively,when compared with those of the beginning of treatments.Both of the soluble protein content and the crude protein content showed a high-low trend line.The soluble protein content of GA3,ABA and CIPC treatment at the previous time of storage increased by 25.73%,39.68%and 31.32%,respectively,and then reduced by 19.17%,33.22%and 17.74%at later storage period,respectively.The crude protein content of GA3,ABA,and CIPC treatment increased by 4.77%,12.67%and 12.65%at the previous time of storage,respectively,and then reduced by 11.37%,18.02%and 8,71%at later storage period,respectively.The C/N ratio of the sprouting promoter treatment was higher than those of the sprouting inhibitor treatments,and all of them showed a downward tendency.4.The SSS activities from different parts of "Chuanyu 117" were gradually reducing before dormancy breaking,while SSS activities form different parts of the different states tubers were rising up after germination period,and reached the maximum in the most active germination period,and then reduced.The SSS activities from different parts of"Favorita" non-sprouting tubers treated with GA3 and ABA were gradually rising up,while reduced when treated by CIPC.The SSS activities from different parts of tubers treated by GA3 were high in the early storage period,and were the highest when treated by ABA in the later storage period,the activities of tubers treated by CIPC were low and the rangeabilities were feeble.Furthermore,the GS activities from different parts of tubers under different treatments were gradually rising up in the early storage period.While the activities of non-sprouting tubers treated by GA3 were lower than that of other treatments and the activities were gradually reducing,the GS activities of sprouting tubers were high and the angeabilities were great.The PPO and POD ctivities of tuber flesh and bud base from different dormancy characteristic cultivars with different treatments were both raised at first then decreased during the storage period.Peak activities of PPO and POD were observed basically consistent with the burst germination period,which indicated that the increasing of PPO and POD activities was one of the physiological basises of tuber's dormancy breaking and sprouting.GA3,ABA and CIPC could significantly affect the PPO and POD activities of bud base and tuber flesh.GA3 could enhance the PPO and POD activities in the bud base of the treated tubers,meanwhile the sprouting-inhibitors ABA and CIPC could weaken the oxidases activities in different parts of the non-sprout tuber,the PPO and POD activities of ABA treatment increased during dormancy releasing process,especially the "Chuanyu 117".5.The study found out adding antioxidant PVP in the extracting solution and adjusting the pH to 8.0 could increase the extraction efficiency,enhancing the recovery and stability of endogenous hormones effectively.By using the H2O and methyl alcohol as the binary moving phase,under the gradient elution program that eluting by 60%methyl alcohol from 0 to 8th minute,increasing the concentration to 100%from 8th to 15th minute and remaining unchanged still 40th minute could obtain better detection effect of the 4 hormones.Using the optimized method above extract and determine the endogenous hormones content change during the whole storage period,the research indicated that the GA content in the bud base of the tubers treated by GA3 was high while the GA content in the tuber flesh of tubers was much lower,the ZT content in the different parts of the tubers in different time point was high but the ABA content was low,the IAA content was high after germination.The GA,ZT content of different parts of the non-sprouting tubers treated by ABA were low and the ABA,IAA content were high,the GA,ZT content reached to the maximum about germination period,and then the ABA,IAA content gradually reduced.The ABA and IAA content in different parts of tubers treated by CIPC were high in the early storage period,and the GA and ZT content were low in the whole storage period.