Effects Of Plant Growth Regulators On Seed Germination And Seedling Growth Of Kadsura Coccinea

Kadsura coccinea is a plant with great development potential,which integrates edible,ornamental and medicinal functions.The long dormancy period and low germination rate of Kadsura coccinea seeds have formed a great obstacle to its seedling cultivation,and it is also a technical problem encountered in the breeding and cultivation of Kadsura coccinea.The use of plant growth regulators is an effective way to promote seed germination and seedling growth.In this study,the seeds of Kadsura coccinea were soaked with different concentrations of plant growth regulators to study the effects of plant growth regulators on seed germination and seedling growth,including gibberellin(GA3),naphthaleneacetic acid(NAA),salicylic acid(SA),6-benzylaminopurine(6-BA),as well as the effects of the optimal treatment on the physiological and biochemical characteristics during seedling germination,such as the contents of storage substances,the activity of antioxidant enzymes(SOD,POD,CAT)and the contents of malondialdehyde(MDA)in the early stage of seed germination.The main results are as follows:(1)Seeds soaking with appropriate concentrations of plant growth regulators significantly improved the germination rate and germination potential of Kadsura coccinea seeds,and shortened the germination time.The germination rate of seeds treated with 200 mg·L-1 6-BA and 100 mg·L-1 SA was significantly higher than that of other groups(P<0.05),which was 87.33%,which had a 18.66%increase over CK(68.67%).The germination potential of seeds treated with 100 mg·L-1 SA was significantly higher than that of other groups(P<0.05),which was 71.33%,which had a 34.00%increase over CK(37.33%),followed by 200 mg·L-1 6-BA,which was 66.67%,which was 29.34%higher than that of CK.The average germination rate of 200 mg·L-1 6-BA treatment was significantly higher than that of other groups(P<0.05),which was 44.65 d,which was 8.15 d earlier than CK(52.80 d),followed by 100 mg·L-1 SA,which was 45.42d,which was 7.38 d earlier than CK.In summary,100 mg·L-1 SA and 200 mg·L-1 6-BA had the best effect on seed germination.(2)The effects of the best treatment(100 mg·L-1 SA,200 mg·L-1 6-BA)on the physiological and biochemistry effects of Kadsura coccinea at early germination stage showed that the soluble sugar content of seeds soaked with SA and 6-BA was higher than that of CK at all time points.The seed starch content of SA was significantly higher than that of CK at 25d after soaking(P<0.05),significantly lower than that of CK at 30d after soaking(P<0.05),seed starch content in 6-BA group at 5 d,15 d and 30 d after soaking was significantly lower than that in CK group at 5 d,15 d and 30 d after soaking(P<0.05).The soluble protein in seeds after SA soaking at 5 d,15 d,20 d and 25 d was significantly lower than that of CK(P<0.05),and the soluble protein in seeds after 6-BA soaking at 5 d,15 d,20 d and 25 d was significantly lower than that of CK(P<0.05).Overall,the activity of antioxidant enzymes of the seeds with SA and 6-BA presoaking were higher than that of CK,SA and 6-BA treatment increased the content of MDA at the early stage of seed germination.In conclusion,SA and 6-BA soaking can promote seed germination by affecting the contents of stored nutrients,antioxidant enzyme activity and MDA contents in the early stage of germination of Kadsura coccinea.(3)The suitable concentration of plant growth regulators soaking improved the growth of Kadsura coccinea seedlings.The effect of 150 mg·L-1 GA3 treatment was had the best effect on promoting the growth of Kadsura coccinea seedlings,and the seedling height was 9.01 cm,which was 9.74%higher than that of CK.150 mg L-1 GA3 treatment has the best effect on the stem base thickening growth of Kadsura coccinea seedlings,and its ground diameter was 3.38 mm,which was 13.04%higher than that of CK.The effect of 100 and 200 mg·L-1 NAA treatment on leaf growth was significantly higher than that of other groups(P<0.05),the leaf length was 5.64 cm and 5.58 cm,and the leaf width was 3.63 cm and 3.56 cm,respectively.The effect of 150 and 200 mg L-1 6-BA treatment on increasing the number of fibrous roots was significantly higher than that in other groups(P<0.05),and the number of fibrous roots in 150 mg·L-1 6-BA treatment was 38.27 and 38.17,which were 26.43%and 26.10%higher than that in CK group,respectively.(4)Analysis and comprehensive evaluation of plant growth regulators on seed germination and seedling growth factors of Kadsura coccinea.Based on the principle of eigenvalue greater than 1,the cumulative variance contribution rate of the two common factors extracted was 81.03%.Factor F1 was related to seedling growth,and the top five groups were 200 mg·L-1 NAA,150 mg·L-1 GA3,100 mg·L-1 NAA,100 mg·L-1 GA3 and 200 mg·L-1 SA.F2 represented seed germination,and the top five groups were 200 mg·L-16-BA,100 mg·L-1 SA,150 mg-L-1 GA3,150 mg·L-1 NAA and 100 mg·L-1 SA.The top five groups with comprehensive scores were 100 mg·L-1 SA,150 mg·L-1 GA3,100 mg·L-1 NAA,200 mg·L-1 NAA and 100 mg·L-1 GA3.In conclusion,the suitable concentration of four plant growth regulators can significantly promote the seed germination and seedling growth of the Kadsura coccinea,and the optimal treatment(200 mg·L-1 6-BA,100 mg·L-1 SA)can increase the contents of soluble sugar,reduce soluble protein,change the content of starch,improve the activities of SOD,POD and CAT,and increase the content of MDA,thereby promoting seed germination of the Kadsura coccinea seeds.Through factor analysis and comprehensive evaluation,100 mg·L-1 SA has the highest score and is recommended to be used in the production of Kadsura coccinea.