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Abstract [Objectives]This study was conducted to discuss the effects of tillering law and its controlling factors on the growth of Ophiopogon japonicus cv.
[Methods] With O. japonicus cv as an experimental material， its average number of tillers， proliferation coefficient， total number of tillers， death number， germination index， germination rate， fresh root weight， root volume and survival rate were determined.
[Results] The reproductive ability of the NAA treatments was significantly higher than that of the 6-BA treatments， and the average tillering capacity of the 5 mg/L NAA treatment was significantly higher， 90% higher than that of the CK. The proliferation coefficient of O. japonicus cv was significantly better in the NAA treatments than in the 6-BA treatments， and the 5 mg/L-NAA treatment was more significant. The NAA treatments showed total numbers of tillers significantly higher than those of the 6-BA treatments， and exhibited significantly reduced deaths. The 1 mg/L NAA and 10 mg/L 6-BA experimental groups had the strongest germination-promoting effects on O. japonicus cv， which were significantly different from those of other experimental groups， and were 92% and 95% higher than that of the CK， respectively. As to the germination rate indicator of O. japonicus cv， the 1 mg/L NAA and 10 mg/L 6-BA experimental groups exhibited the highest values， which increased by 48% and 43%， respectively， compared with the CK. The 6-BA treatments significantly improved the root growth of O. japonicus cv compared with the NAA treatments， and they significantly promoted root volume of O. japonicus cv. The survival rate of O. japonicus cv treated with hormone NAA was 23.3% higher than that of the 6-BA treatment group.
[Conclusions] This study provide a theoretical basis for improving the reproductive ability of O. japonicus cv and expanding its commercial production.
Key words Ophiopogon japonicus cv; Tiller; 6-BA; NAA
Ophiopogon japonicus cv is also known as Japan Aimaidong. The plant is short and forms a hemisphere cluster， about 10 cm high[1]. Its leaves are thick green， evergreen in all seasons， strongly tolerant to shade and trampling. O. japonicus cv is an excellent ground cover plant that can grow into dense ground felt-like turf with strong ornamental characteristics[2-6].
At present， studies on plant growth regulators promoting plant tillering have shown that spraying 6-BA on wheat seedlings can promote the tillering ability of wheat， especially the tillering ability before winter， which significantly increases the proportion of tillers formed before winter in the final ears[7-10]. When 6-BA was combined with GA3 to treat crops， this method showed a significant interaction and synergistic effect in increasing tiller number and seed number of crops[10-12]. O. japonicus cv is evergreen in all seasons， with high survival rate and strong adaptability. It has been widely applied in southern cities and has high ornamental value. Studies on the induction of embryogenic callus and plant regeneration of O. japonicus cv should be conducted to increase the frequency of differentiation and achieve rapid plant propagation， because O. japonicus cv is long in growth cycle and high in cost and it is difficult to popularize it in production. O. japonicus cv is mostly propagated by branches， which results in a low multiplication coefficient， slow turf formation， long time， high commercial production and management cost， and it is difficult to meet market demand. There have been no studies on promoting the tillering of O. japonicus cv. This study aimed to promote the tillering of O. japonicus cv， increase the speed of turf formation， save costs， and provide a theoretical basis for expanding commercial production. Materials and Methods
Experimental materials
This experiment was carried out in the Nanyuan greenhouse of Kunming University. O. japonicus cv plants with uniform growth were selected. The test plants were planted in 20-30 cm plastic clay pots containing the cultivation substrate prepared from humus soil and perlite in a 3∶1 ratio.
Agent： Naphthylacetate （NAA）; 6 benzyl adenine （6-BA）.
Experimental methods
O. japonicus cv plants were dug out. The plants with consistent growth were selected and then planted into planting pots. Different concentrations of NAA and 6-BA were used to treat the plants， forming seven treatments in total， each of which was repeated 3 times. The various treatments were in random arrangement and adopted uniform conventional fertilizer and water management. They were sprayed with corresponding treatment liquids every 15 d. A total of 210 plants were treated with 10 plants in each treatment.
Among the various treatments， the cultivation substrate of the CK and those that were treated with NAA and 6-BA were all cultivation substrate， humus soil. During the treatment， attention should be paid to the isolation of various treatments. The liquids were sprayed on the leaf surface and back of the leaves every 15 d according to the standard that there was liquid dropping from the leaves.
Determined items
From the beginning of the experiment， the average number of tillers， proliferation coefficient， total number of tillers， death number， germination index， germination rate， fresh root weight， root volume and survival rate in each treatment were recorded or determined.
Data statistics
Data was processed and analyzed using Excel and spss.16 data software.
Results and Analysis
Effects of different treatments on the tillering and proliferation of O. japonicus cv
The average number of tillers and proliferation coefficient were determined in the different treatments A1 （1 mg/L NAA）， A2 （5 mg/L NAA）， A3 （10 mg/L NAA）， B1 （10 mg/L 6-BA）， B2 （30 mg/L 6-BA）， B3 （50 mg/L 6-BA） and the CK group. The results showed （Fig. 1） that the NAA hormone treatment group had significantly better reproductive ability of O. japonicus cv than the 6-BA treatments. A1 （1 mg/L-NAA）， A2 （5 mg/L-NAA） and A3 10mg / L-NAA averaged 4.1， 5.68 and 4.5 tillers， respectively. The A2 experimental group had significantly higher tillering ability than other experimental groups， showing an increase of 90% compared with the CK. The average tillering ability of the A1 and A3 experimental groups was stronger， which increased by 38.9% and 52% compared with the CK， respectively. The average numbers of tillers in B1 （10 mg/L-6-BA）， B2 （30 mg/L-6-BA） and B3 （50 mg/L-6-BA） were， respectively， 3.02， 3.58 and 3.4， all of which had no significant differences from the CK. It can be seen from Fig. 2 that the proliferation coefficients of O. japonicus cv in the NAA hormone treatment group were significantly better than those of the 6-BA treatment group. Specifically， the proliferation coefficients of A1， A2 and A3 were 3.18， 4.79 and 3.25， respectively. The proliferation coefficient of the A2 experimental group was significantly higher than those of other groups， while those of A1 and A3 were comparable， and the difference was not significant. The proliferation coefficients of B1， B2 and B3 were 2.05， 2.36 and 2.39， respectively. The results of B2 and B3 increased by 18.6% and 20% compared with the CK， respectively， while that of B1 was not significantly different from the CK. Effects of different treatments on the total tillers and deaths of O. japonicus cv
The total number of tillers and deaths were determined in the different treatments， A1， A2， A3， B1， B2， B3 and the CK group. According to Table 2， the total numbers of tillers in A1， A2 and A3 were 70， 65 and 66， respectively， and those in B1， B2 and B3 were 58， 56 and 54， respectively. The experimental groups treated with hormone NAA had larger total numbers of tillers than the experimental groups treated with 6-BA， with an average of 33 more. Compared with the CK， the total numbers of tillers in A1， A2 and A3 increased by 66.7%， 54.8%， 57.1%， respectively， and those in B1， B2 and B3 increased by 38%， 33% and 28.7%， respectively. The deaths in A1， A2 and A3 were 3， 6 and 6， respectively， and those in B1， B2 and B3 were 9， 9 and 8， respectively. The deaths in the experimental groups treated with hormone NAA were significantly lower than those in the 6-BA treatment group. Compared with the CK， the deaths in such three experimental groups as A1， A2 and A3 decreased by 66.7%， 33.3% and 33.3%， respectively. The number of deaths in the B3 experimental group was 11% lower than the CK， and the numbers of deaths in the B1 and B2 experimental groups had no differences from the CK.
Effects of different treatments on the germination number of O. japonicus cv
The germination index and germination rate of O. japonicus cv was determined in all the different treatments， A1， A2， A3， B1， B2， B3 and the CK. The germination index was calculated according to Germination rate（%）=Total number of normally germinated plants during the germination test/Number of test plants×100; and the germination index was calculated according to Germination index（GI）=ΣGt/Dt （Gt： number of germinated plant in time t， Dt： corresponding germination days）. The results （Table 2） showed that， A1 and B1 had the strongest germination-promoting effects on O. japonicus cv， which were significantly different from those of other experimental groups， and were 92% and 95% higher than that of the CK， respectively. A2， A3， B2 and the CK all showed certain growth in germination number， and were not significantly different from each other. From the perspective of the germination rate indicator of O. japonicus cv， A1 and B1 exhibited the highest values， which increased by 48% and 43%， respectively， compared with the CK， with significant differences from other experimental groups. There were no significant differences between the remaining experimental groups. A2， A3， B2 and the CK showed consistency with the germination index， and also exhibited increased germination rates without significant differences. Effects of different treatments on the root growth of O. japonicus cv
The fresh root weight and root volume of O. japonicus cv were determined in all the different treatments， A1， A2， A3， B1， B2， B3 and the CK. The results showed （Table 3） that the different treatment groups had significantly different effects on the roots of O. japonicus cv. The root growth of O. japonicus cv was significantly better in the 6-BA hormone treatment group than in the NAA treatment group. The fresh root weights in B3， B2 and B1 were 0.058， 0.052 and 0.048 g， respectively， which had no significant differences between each other， but were all significantly higher than that in the CK （0.019 g）. The fresh root weights in A1， A2 and A3 were 0.035， 0.032 and 0.038 g， respectively， which increased by 45%， 33% and 58%， respectively， compared with the CK （0.019 g）. The 6-BA hormone treatment group significantly promoted the root volume growth of O. japonicus cv. The root volumes in B3， B2 and B1 were， respectively， 0.31， 0.29 and 0.26 cm3， which were significantly different from those of the NAA treatments， A1 （0.13 cm3）， A2 （0.15 cm3） and A3 （0.14 cm3） and the CK （0.11 cm3）， while there were no significant differences between the NAA experimental group and the CK.
Effects of different treatments on the survival rate of O. japonicus cv
The survival rate of O. japonicus cv was determined in the different treatments， A1， A2， A3， B1， B2， B3 and the CK group. The results （Table 4） showed that the survival rates of the three concentrations in group A were larger than those of the three concentrations in group B. At the maximum concentration of 10 mg/L in group A， the survival rate of O. japonicus cv was the highest at 96.7%. At the concentrations of 20 and 30 mg/L in group B， the survival rate of O. japonicus cv was 86.7%. The survival rate of O. japonicus cv treated with hormone NAA was 23.3% higher than that of the 6-BA treatment group. The survival rates of the two experimental groups A1 and A3 were 3.3 and 6.7 percentage points higher than that of the CK， respectively. The survival rate of A2 was comparable to that of the ordinary CK group， i.e.， the use of 5 mg/L NAA had no effect on the survival rate of O. japonicus cv. The survival rates of B1， B2 and B3 were 6.7， 3.3， and 3.3 percentage points lower than that of the CK. The use of plant growth regulator 6-BA at a certain concentration negatively affected the survival rate of O. japonicus cv. Conclusions
The growth of plants is mainly regulated by the interaction of auxin and cytokinin which is synthesized in the roots or stems. Seed germination is a relatively complicated material metabolism process， while plant growth regulators participate in and regulate the process of seed germination， which can make changes in enzymes and internal nutrients[14]. Some literatures have shown that 30 mg/kg GA3+30 mg/kg PCPA can significantly promote the vertical and horizontal diameters of cherry tomatoes， and have the best effects in promoting fruit growth and improving quality[15]. The combined application of CPA and 6-BA can significantly increase fruit volume， fruit weight and abscisic acid content in eggplant[16]. The experiment of dipping and irrigating potted Cymbidium hybridum with different concentrations of 6-BA， NAA and PP333 showed that dipping roots of C. hybridum with 100 mg/L 6-BA+200 mg/L PP333 mixed solution had a significant effect on the tillering rate of C. hybridum， and the mixed use of NAA， 6-BA and PP333 could increase the chlorophyll content of plant leaves and promote tillering[17]. When soaking the roots of Dendrobium with GA3， 6-BA， NAA and PP333 for 2 h at 10 d before tillering， it was found that 6-BA， NAA and PP333 could increase the effective tiller number. Among them， the treatment with 10 mg/L 6-BA had the most significant effect， while the GA3 treatment inhibited tillering， but promoted budding[18]. ZHANG reported[19] that plant growth regulators could promote the germination of tomato seeds. Specifically， 1 mg/kg of NAA had the best effect on tomato seed germination. The NAA-treated tomato seeds had the highest dry and fresh root weights， which were 24.4% and 57.7% higher than those of the CK， respectively. Tillering ability is greatly affected by climatic conditions. The condition of high temperature and strong light is to be benefit of tillering， and rainy and dimly weather is not conducive to tillering. The tillers of different types of corn are adjusted by sowing date and planting density， and when the planting density increases， the maximum tiller number and the final tiller number decrease[21]. Lycoris haywardii bulbs were treated with different concentrations of NAA and 6-BA before the leaf emergence stage， in order to study the impacts of plant growth regulators on the endogenous hormones and vegetative growth of L. haywardii. The research results showed that continuous application of 1 mg/L NAA or 5 mg/L 6-BA could promote bulb diameter increase. Meanwhile， NAA was also significantly related to increasing the bulb reproduction coefficient. There were significant differences in the content of endogenous IAA between the various treatments and the CK. Conclusions
The determination of the average number of tillers and proliferation ability of different treatments showed that the NAA treatment group had reproductive ability of O. japonicus cv significantly better than the 6-BA treatment group. The average tillering capacity of the A2 experimental group was significantly higher than those of other experimental groups， showing an increase of 90% compared with the CK. The proliferation coefficient of O. japonicus cv was significantly better in the NAA experimental groups than in the 6-BA groups， and the proliferation coefficient of the 5 mg/L NAA group was significantly higher than other groups.
The determination of total number of tillers and deaths in the different treatments showed that the experimental groups treated with hormone NAA had larger total numbers of tillers than the experimental groups treated with 6-BA， with an average of 33 more. Compared with the CK， the total numbers of tillers in A1， A2 and A3 increased by 66.7%， 54.8%， 57.1%， respectively， and those in B1， B2 and B3 increased by 38%， 33% and 28.7%， respectively. The deaths in the experimental groups treated with hormone NAA were significantly lower than those in the 6-BA treatment groups. Compared with the CK， the deaths in the three experimental groups A1， A2 and A3 decreased by 66.7%， 33.3% and 33.3%， respectively.
The determination of germination index and germination rate of O. japonicus cv in the different treatments showed that A1 and B1 had the strongest germination-promoting effects on O. japonicus cv， which were significantly different from those of other experimental groups， and were 92% and 95% higher than that of the CK， respectively. As to the germination rate indicator of O. japonicus cv， A1 and B1 exhibited the highest values， which increased by 48% and 43%， respectively， compared with the CK.
The determination of fresh root weight and root volume of O. japonicus cv in the different treatments showed that the growth of O. japonicus cvs root system in the 6-BA hormone treatment groups was significantly better than that of the NAA treatment groups. The 6-BA hormone treatment groups significantly promoted the root volume growth of O. japonicus cv.
The determination of the survival rate of O. japonicus cv in the different treatment groups showed that the survival rates of the three concentrations in group A were larger than those of the three concentrations in group B. At the maximum concentration of 10 mg/L in group A， the survival rate of O. japonicus cv was the highest at 96.7%. At the concentrations of 20 and 30 mg/L in group B， the survival rate of O. japonicus cv was 86.7%. The survival rate of O. japonicus cv treated with hormone NAA was 23.3% higher than that of the 6-BA treatment group. References
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[2] GUI L， GUO CR. Application of Ophiopogon japonicus in landscaping[J]. Journal of Green Science and Technology， 2012（07）： 19-20. （in Chinese）
[3] WU XH. Ophiopogon japonicus （L. f.） Ker-Gawl. cv. Nanus[J]. Flowers Trees Potted Landscape， 2009（05）： 45. （in Chinese）
[4] WANG GP， HUANG MR. Induction of embryogenic callus and plantlet regeneration of Ophiopogon japonicus cv. "Nanus"[J]. Plant Physiology Communications， 2002（01）： 43. （in Chinese）
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[7] TAN XM， PENG LL， LI MY， et al. Effects of seedling quantity on tillering and panicle formation in mechanically transplanted double-cropping rice[J]. Acta Agriculturae Universitis Jiangxiensis： 1-12[2019-05-05]. （in Chinese）
[8] CUI YK， WANG NN， TIAN ZW， et al. Effect of water deficit during tillering and jointing stages on nitrogen accumulation and translocation in winter wheat[J]. Journal of Triticeae Crops， 2019， 39（03）： 322-328. （in Chinese）
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[12] ZHANG YL. The studies on the internal and external control mechanism of tiller formation[D]. Harbin： Northeast Agricultural University， 2017. （in Chinese）
[13] LU N. Effects of light intensity， fertilizers and growth regulators on the growth of Fescue arundinacea Shreb.[D]. Shanghai： Shanghai Jiaotong University， 2010. （in Chinese）
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[Methods] With O. japonicus cv as an experimental material， its average number of tillers， proliferation coefficient， total number of tillers， death number， germination index， germination rate， fresh root weight， root volume and survival rate were determined.
[Results] The reproductive ability of the NAA treatments was significantly higher than that of the 6-BA treatments， and the average tillering capacity of the 5 mg/L NAA treatment was significantly higher， 90% higher than that of the CK. The proliferation coefficient of O. japonicus cv was significantly better in the NAA treatments than in the 6-BA treatments， and the 5 mg/L-NAA treatment was more significant. The NAA treatments showed total numbers of tillers significantly higher than those of the 6-BA treatments， and exhibited significantly reduced deaths. The 1 mg/L NAA and 10 mg/L 6-BA experimental groups had the strongest germination-promoting effects on O. japonicus cv， which were significantly different from those of other experimental groups， and were 92% and 95% higher than that of the CK， respectively. As to the germination rate indicator of O. japonicus cv， the 1 mg/L NAA and 10 mg/L 6-BA experimental groups exhibited the highest values， which increased by 48% and 43%， respectively， compared with the CK. The 6-BA treatments significantly improved the root growth of O. japonicus cv compared with the NAA treatments， and they significantly promoted root volume of O. japonicus cv. The survival rate of O. japonicus cv treated with hormone NAA was 23.3% higher than that of the 6-BA treatment group.
[Conclusions] This study provide a theoretical basis for improving the reproductive ability of O. japonicus cv and expanding its commercial production.
Key words Ophiopogon japonicus cv; Tiller; 6-BA; NAA
Ophiopogon japonicus cv is also known as Japan Aimaidong. The plant is short and forms a hemisphere cluster， about 10 cm high[1]. Its leaves are thick green， evergreen in all seasons， strongly tolerant to shade and trampling. O. japonicus cv is an excellent ground cover plant that can grow into dense ground felt-like turf with strong ornamental characteristics[2-6].
At present， studies on plant growth regulators promoting plant tillering have shown that spraying 6-BA on wheat seedlings can promote the tillering ability of wheat， especially the tillering ability before winter， which significantly increases the proportion of tillers formed before winter in the final ears[7-10]. When 6-BA was combined with GA3 to treat crops， this method showed a significant interaction and synergistic effect in increasing tiller number and seed number of crops[10-12]. O. japonicus cv is evergreen in all seasons， with high survival rate and strong adaptability. It has been widely applied in southern cities and has high ornamental value. Studies on the induction of embryogenic callus and plant regeneration of O. japonicus cv should be conducted to increase the frequency of differentiation and achieve rapid plant propagation， because O. japonicus cv is long in growth cycle and high in cost and it is difficult to popularize it in production. O. japonicus cv is mostly propagated by branches， which results in a low multiplication coefficient， slow turf formation， long time， high commercial production and management cost， and it is difficult to meet market demand. There have been no studies on promoting the tillering of O. japonicus cv. This study aimed to promote the tillering of O. japonicus cv， increase the speed of turf formation， save costs， and provide a theoretical basis for expanding commercial production. Materials and Methods
Experimental materials
This experiment was carried out in the Nanyuan greenhouse of Kunming University. O. japonicus cv plants with uniform growth were selected. The test plants were planted in 20-30 cm plastic clay pots containing the cultivation substrate prepared from humus soil and perlite in a 3∶1 ratio.
Agent： Naphthylacetate （NAA）; 6 benzyl adenine （6-BA）.
Experimental methods
O. japonicus cv plants were dug out. The plants with consistent growth were selected and then planted into planting pots. Different concentrations of NAA and 6-BA were used to treat the plants， forming seven treatments in total， each of which was repeated 3 times. The various treatments were in random arrangement and adopted uniform conventional fertilizer and water management. They were sprayed with corresponding treatment liquids every 15 d. A total of 210 plants were treated with 10 plants in each treatment.
Among the various treatments， the cultivation substrate of the CK and those that were treated with NAA and 6-BA were all cultivation substrate， humus soil. During the treatment， attention should be paid to the isolation of various treatments. The liquids were sprayed on the leaf surface and back of the leaves every 15 d according to the standard that there was liquid dropping from the leaves.
Determined items
From the beginning of the experiment， the average number of tillers， proliferation coefficient， total number of tillers， death number， germination index， germination rate， fresh root weight， root volume and survival rate in each treatment were recorded or determined.
Data statistics
Data was processed and analyzed using Excel and spss.16 data software.
Results and Analysis
Effects of different treatments on the tillering and proliferation of O. japonicus cv
The average number of tillers and proliferation coefficient were determined in the different treatments A1 （1 mg/L NAA）， A2 （5 mg/L NAA）， A3 （10 mg/L NAA）， B1 （10 mg/L 6-BA）， B2 （30 mg/L 6-BA）， B3 （50 mg/L 6-BA） and the CK group. The results showed （Fig. 1） that the NAA hormone treatment group had significantly better reproductive ability of O. japonicus cv than the 6-BA treatments. A1 （1 mg/L-NAA）， A2 （5 mg/L-NAA） and A3 10mg / L-NAA averaged 4.1， 5.68 and 4.5 tillers， respectively. The A2 experimental group had significantly higher tillering ability than other experimental groups， showing an increase of 90% compared with the CK. The average tillering ability of the A1 and A3 experimental groups was stronger， which increased by 38.9% and 52% compared with the CK， respectively. The average numbers of tillers in B1 （10 mg/L-6-BA）， B2 （30 mg/L-6-BA） and B3 （50 mg/L-6-BA） were， respectively， 3.02， 3.58 and 3.4， all of which had no significant differences from the CK. It can be seen from Fig. 2 that the proliferation coefficients of O. japonicus cv in the NAA hormone treatment group were significantly better than those of the 6-BA treatment group. Specifically， the proliferation coefficients of A1， A2 and A3 were 3.18， 4.79 and 3.25， respectively. The proliferation coefficient of the A2 experimental group was significantly higher than those of other groups， while those of A1 and A3 were comparable， and the difference was not significant. The proliferation coefficients of B1， B2 and B3 were 2.05， 2.36 and 2.39， respectively. The results of B2 and B3 increased by 18.6% and 20% compared with the CK， respectively， while that of B1 was not significantly different from the CK. Effects of different treatments on the total tillers and deaths of O. japonicus cv
The total number of tillers and deaths were determined in the different treatments， A1， A2， A3， B1， B2， B3 and the CK group. According to Table 2， the total numbers of tillers in A1， A2 and A3 were 70， 65 and 66， respectively， and those in B1， B2 and B3 were 58， 56 and 54， respectively. The experimental groups treated with hormone NAA had larger total numbers of tillers than the experimental groups treated with 6-BA， with an average of 33 more. Compared with the CK， the total numbers of tillers in A1， A2 and A3 increased by 66.7%， 54.8%， 57.1%， respectively， and those in B1， B2 and B3 increased by 38%， 33% and 28.7%， respectively. The deaths in A1， A2 and A3 were 3， 6 and 6， respectively， and those in B1， B2 and B3 were 9， 9 and 8， respectively. The deaths in the experimental groups treated with hormone NAA were significantly lower than those in the 6-BA treatment group. Compared with the CK， the deaths in such three experimental groups as A1， A2 and A3 decreased by 66.7%， 33.3% and 33.3%， respectively. The number of deaths in the B3 experimental group was 11% lower than the CK， and the numbers of deaths in the B1 and B2 experimental groups had no differences from the CK.
Effects of different treatments on the germination number of O. japonicus cv
The germination index and germination rate of O. japonicus cv was determined in all the different treatments， A1， A2， A3， B1， B2， B3 and the CK. The germination index was calculated according to Germination rate（%）=Total number of normally germinated plants during the germination test/Number of test plants×100; and the germination index was calculated according to Germination index（GI）=ΣGt/Dt （Gt： number of germinated plant in time t， Dt： corresponding germination days）. The results （Table 2） showed that， A1 and B1 had the strongest germination-promoting effects on O. japonicus cv， which were significantly different from those of other experimental groups， and were 92% and 95% higher than that of the CK， respectively. A2， A3， B2 and the CK all showed certain growth in germination number， and were not significantly different from each other. From the perspective of the germination rate indicator of O. japonicus cv， A1 and B1 exhibited the highest values， which increased by 48% and 43%， respectively， compared with the CK， with significant differences from other experimental groups. There were no significant differences between the remaining experimental groups. A2， A3， B2 and the CK showed consistency with the germination index， and also exhibited increased germination rates without significant differences. Effects of different treatments on the root growth of O. japonicus cv
The fresh root weight and root volume of O. japonicus cv were determined in all the different treatments， A1， A2， A3， B1， B2， B3 and the CK. The results showed （Table 3） that the different treatment groups had significantly different effects on the roots of O. japonicus cv. The root growth of O. japonicus cv was significantly better in the 6-BA hormone treatment group than in the NAA treatment group. The fresh root weights in B3， B2 and B1 were 0.058， 0.052 and 0.048 g， respectively， which had no significant differences between each other， but were all significantly higher than that in the CK （0.019 g）. The fresh root weights in A1， A2 and A3 were 0.035， 0.032 and 0.038 g， respectively， which increased by 45%， 33% and 58%， respectively， compared with the CK （0.019 g）. The 6-BA hormone treatment group significantly promoted the root volume growth of O. japonicus cv. The root volumes in B3， B2 and B1 were， respectively， 0.31， 0.29 and 0.26 cm3， which were significantly different from those of the NAA treatments， A1 （0.13 cm3）， A2 （0.15 cm3） and A3 （0.14 cm3） and the CK （0.11 cm3）， while there were no significant differences between the NAA experimental group and the CK.
Effects of different treatments on the survival rate of O. japonicus cv
The survival rate of O. japonicus cv was determined in the different treatments， A1， A2， A3， B1， B2， B3 and the CK group. The results （Table 4） showed that the survival rates of the three concentrations in group A were larger than those of the three concentrations in group B. At the maximum concentration of 10 mg/L in group A， the survival rate of O. japonicus cv was the highest at 96.7%. At the concentrations of 20 and 30 mg/L in group B， the survival rate of O. japonicus cv was 86.7%. The survival rate of O. japonicus cv treated with hormone NAA was 23.3% higher than that of the 6-BA treatment group. The survival rates of the two experimental groups A1 and A3 were 3.3 and 6.7 percentage points higher than that of the CK， respectively. The survival rate of A2 was comparable to that of the ordinary CK group， i.e.， the use of 5 mg/L NAA had no effect on the survival rate of O. japonicus cv. The survival rates of B1， B2 and B3 were 6.7， 3.3， and 3.3 percentage points lower than that of the CK. The use of plant growth regulator 6-BA at a certain concentration negatively affected the survival rate of O. japonicus cv. Conclusions
The growth of plants is mainly regulated by the interaction of auxin and cytokinin which is synthesized in the roots or stems. Seed germination is a relatively complicated material metabolism process， while plant growth regulators participate in and regulate the process of seed germination， which can make changes in enzymes and internal nutrients[14]. Some literatures have shown that 30 mg/kg GA3+30 mg/kg PCPA can significantly promote the vertical and horizontal diameters of cherry tomatoes， and have the best effects in promoting fruit growth and improving quality[15]. The combined application of CPA and 6-BA can significantly increase fruit volume， fruit weight and abscisic acid content in eggplant[16]. The experiment of dipping and irrigating potted Cymbidium hybridum with different concentrations of 6-BA， NAA and PP333 showed that dipping roots of C. hybridum with 100 mg/L 6-BA+200 mg/L PP333 mixed solution had a significant effect on the tillering rate of C. hybridum， and the mixed use of NAA， 6-BA and PP333 could increase the chlorophyll content of plant leaves and promote tillering[17]. When soaking the roots of Dendrobium with GA3， 6-BA， NAA and PP333 for 2 h at 10 d before tillering， it was found that 6-BA， NAA and PP333 could increase the effective tiller number. Among them， the treatment with 10 mg/L 6-BA had the most significant effect， while the GA3 treatment inhibited tillering， but promoted budding[18]. ZHANG reported[19] that plant growth regulators could promote the germination of tomato seeds. Specifically， 1 mg/kg of NAA had the best effect on tomato seed germination. The NAA-treated tomato seeds had the highest dry and fresh root weights， which were 24.4% and 57.7% higher than those of the CK， respectively. Tillering ability is greatly affected by climatic conditions. The condition of high temperature and strong light is to be benefit of tillering， and rainy and dimly weather is not conducive to tillering. The tillers of different types of corn are adjusted by sowing date and planting density， and when the planting density increases， the maximum tiller number and the final tiller number decrease[21]. Lycoris haywardii bulbs were treated with different concentrations of NAA and 6-BA before the leaf emergence stage， in order to study the impacts of plant growth regulators on the endogenous hormones and vegetative growth of L. haywardii. The research results showed that continuous application of 1 mg/L NAA or 5 mg/L 6-BA could promote bulb diameter increase. Meanwhile， NAA was also significantly related to increasing the bulb reproduction coefficient. There were significant differences in the content of endogenous IAA between the various treatments and the CK. Conclusions
The determination of the average number of tillers and proliferation ability of different treatments showed that the NAA treatment group had reproductive ability of O. japonicus cv significantly better than the 6-BA treatment group. The average tillering capacity of the A2 experimental group was significantly higher than those of other experimental groups， showing an increase of 90% compared with the CK. The proliferation coefficient of O. japonicus cv was significantly better in the NAA experimental groups than in the 6-BA groups， and the proliferation coefficient of the 5 mg/L NAA group was significantly higher than other groups.
The determination of total number of tillers and deaths in the different treatments showed that the experimental groups treated with hormone NAA had larger total numbers of tillers than the experimental groups treated with 6-BA， with an average of 33 more. Compared with the CK， the total numbers of tillers in A1， A2 and A3 increased by 66.7%， 54.8%， 57.1%， respectively， and those in B1， B2 and B3 increased by 38%， 33% and 28.7%， respectively. The deaths in the experimental groups treated with hormone NAA were significantly lower than those in the 6-BA treatment groups. Compared with the CK， the deaths in the three experimental groups A1， A2 and A3 decreased by 66.7%， 33.3% and 33.3%， respectively.
The determination of germination index and germination rate of O. japonicus cv in the different treatments showed that A1 and B1 had the strongest germination-promoting effects on O. japonicus cv， which were significantly different from those of other experimental groups， and were 92% and 95% higher than that of the CK， respectively. As to the germination rate indicator of O. japonicus cv， A1 and B1 exhibited the highest values， which increased by 48% and 43%， respectively， compared with the CK.
The determination of fresh root weight and root volume of O. japonicus cv in the different treatments showed that the growth of O. japonicus cvs root system in the 6-BA hormone treatment groups was significantly better than that of the NAA treatment groups. The 6-BA hormone treatment groups significantly promoted the root volume growth of O. japonicus cv.
The determination of the survival rate of O. japonicus cv in the different treatment groups showed that the survival rates of the three concentrations in group A were larger than those of the three concentrations in group B. At the maximum concentration of 10 mg/L in group A， the survival rate of O. japonicus cv was the highest at 96.7%. At the concentrations of 20 and 30 mg/L in group B， the survival rate of O. japonicus cv was 86.7%. The survival rate of O. japonicus cv treated with hormone NAA was 23.3% higher than that of the 6-BA treatment group. References
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