Cultural Practices for Propagation of Spatholobus suberectus via Cutting into Polybags

Maojin YE, Ribin HUANG, Chunyun CHEN, Dachang NING, Su ZHANG, Shufu CHEN,2, Qingsong DONG,2

1.Guangxi Nanyaokangyuan Investment Co.Ltd., Yulin 537035, China; 2.Guangxi Botanical Garden of Medicinal Plants, Nanning 530023, China

Abstract In this paper, the propagation of Spatholobus suberectus Dunn.was optimized based on the research results conducted in propagation for many years and the actual need for the planting materials.According to the requirements of Good Agricultural Practices for Chinese Medicinal Drugs, cultural practices for propagation of S. suberectus were summed up and standardized, including the environmental requirements, land preparation, bed preparation, cutting of scions, cuttings treatment, cutting, management of cuttings at the nursery, bagged cuttings ready for transplanting, packing and handling, transportation, and preparation of records for archives.

Key words Spatholobus suberectus Dunn., Bagged cuttings, Cutting directly into bags, Cultural practices, Chinese traditional medicinal plants in southern China

1 Introduction

Caulis Spatholobi, a famous southern medicine, is the dry cane of leguminous plantSpatholobussuberectusDunn.It is distributed in Guangxi, Guangdong, Yunnan, Fujian and other provinces of China.It has the effects of promoting blood circulation, regulating menstruation and relieving pain, and relaxing muscles and collaterals, so it can be used to cure irregular menstruation, dysmenorrhea, amenorrhea, rheumatic arthralgia, numbness, paralysis, blood deficiency and chlorosis[1].As a traditional Chinese medicine that has been used for thousands of years, Caulis Spatholobi is the raw material of many famous Chinese patent medicines.Caulis Spatholobi has always relied on wild resources.The long-term and disorderly application and the large-scale development of mountainous areas have nearly exhausted domestic resources.The raw materials circulating in the market are almost imported from Vietnam’s border trade through the ports of Guangxi and Yunnan in China, and the production area tends to extend from neighboring countries in Vietnam.Although the incoming goods from border trade are still abundant, the specifications have been decreasing year by year, and the price has risen steadily; in the years when there are trade frictions, the price has risen rapidly.Therefore, companies and individuals have successively established medicinal planting bases in recent years.From the perspective of the safety of medicinal resources and medication, the standardized and large-scale cultivation ofS.suberectusshould be included in the national biosafety strategy.

The flowers and fruits ofS.suberectusare rare, so its seedling breeding is mainly asexual reproduction.Cutting breeding technology has been successful after long-term research by many scientific research units and enterprises.However, there are the following problems in planting practice.Firstly, the root system of the bare-rooted seedlings ofS.suberectusgenerally produced in the market is not very developed, and the roots are easily broken during the lifting of seedlings.Especially after long-distance transportation, the quality declines quickly, and the survival rate after planting is low.Secondly, it is usually planted under forests or in sloping fields.Such plots are usually short of water.After being planted, the lack of seedlings is serious due to insufficient water supply.When the planting area is large, the survival rate is only 20%-30% in many bases, which seriously affects planting efficiency and base benefits.

Based on the research results of seedling breeding ofS.suberectusover the years[2-3], in view of the outstanding problems in the seedling market, combined with the actual demand for seedlings in the construction of planting bases, the project team studied the bag seedling breeding ofS.suberectus, optimized and improved its seedling breeding technology, and summarized the technical regulation of direct breeding of its bag seedlings.The regulation stipulates the specific methods and technical parameters that should be adopted in the environmental requirements of seedling breeding fields, soil preparation, nursery bed preparation, cuttings cutting, cuttings processing, cuttings, seedling management, leaving the nursery, packaging and transportation, and file records.The formulation of this regulation is of positive significance for promoting the standardization and standardization of the seedling breeding ofS.suberectusand enhancing the market competitiveness of seedling products.

2 Environmental requirements of seedling breeding fields

In subtropical warm and humid areas, a breeding nursery ofS.suberectuscan be built on the slopes or fields far away from pollution sources, with flat land, leeward to the sun, convenient irrigation and drainage, and convenient transportation.The ambient air of the nursery should meet the requirements of the AmbientAirQualityStandards(GB 3095-2012)[4]; the soil should meet the requirements of theEnvironmentalQualityStandardforSoils(GB 15618-1995)[5]; the irrigation water should meet the requirements of theStandardforIrrigationWaterQuality(GB 5084-2005)[6].

3 Soil preparation

Seedlings can be cultivated in a shed or in a open field.Trees, weeds, stones, and debris are removed, and the nursery site is leveled; road networks, drainage systems, and irrigation systems are designed.A seedbed with a height of 15-20 cm and a width of 100-120 cm is made.The working path between the borders is about 40 cm, and the length of the border depends on the terrain.After the borders are prepared, the borders are thinly sprinkled with quicklime for disinfection, and the usage of quicklime is about 225 kg/ha.

4 Preparation of seedling beds

Non-woven bags are used to cultivate seedlings, and neatly placed on a seedling bed after loading the substrate.The non-woven bags are 15-20 cm long and 22-25 cm high.The volume ratio of the seedling substrate is as follows∶yellow heart soil∶river sand∶chaff(or coconut bran, edible fungus scraps,etc.)∶organic fertilizer=7∶1∶1∶1.The proportion of the substrate in each non-woven bag is 90%.

5 Taking a cutting

A cutting can be taken from November to next April.HealthyS.suberectusplants with many branches and growing luxuriantly are chosen as the mother plants.The semi-ligninized branches that are 1-2 years old are cut off on cloudy days or when it is cool in the morning and evening.The branches with a diameter of 0.8-2.0 cm are cut, and the upper cut is flat, while the lower cut is diagonal.Each cutting is 15-25 cm long and has 3-4 nodes.

6 Cutting treatment

The the lower part of the cut cuttings(1/3-1/2)is first soaked and disinfected with 750 times 50% wettable carbendazim solution for about 30 min, and then soaked in 500 mg/L potassium indole butyrate for 5 min.Finally, they are taken out and dried in the air.

7 Cuttage

In the center of each seedling bag with the substrate, a wooden stick thicker than the cuttings is inserted to form a deep hole, and then a cutting with a bud head up is inserted into the hole.The two nodes are buried in the soil, and the seedling bags are slightly shaken to make the substrate and the cuttings contact closely.The inserted seedling bags are arranged and placed, into which water is poured in time.

8 Management of cuttings

8.1 Putting up a shed and management of light, temperature and humidityFor outdoor seedling cultivation, a small arch shed is built on the border with the cuttings, and the height of the arch shed is 1.0-1.2 m.The arch shed is covered with a sunshade net to make the shade degree between 50% and 70%.When the temperature is lower than 20 ℃, a white film is covered for heat preservation; when the temperature is higher than 35 ℃, the film is removed to cool down; the humidity in the arch shed is controlled at 60%-80%.For seedlings growing in a nursery greenhouse, attention should be paid to the management of light, temperature and humidity, and the requirements are the same as those in the small arched shed.

8.2 Irrigation and drainageThe cuttings are poured thoroughly once a day.In summer, when the temperature is high and the transpiration is fast, they can be poured once in the morning and once in the evening.After spraying and in rainy days, drainage is conducted timely to avoid rotted roots and pests.

8.3 WeedingWhen weeds are about 5 cm high, they must be pulled out in time to avoid contention for water and fertilizer and then affect the growth of seedlings.Weeds should be removed manually, and chemical herbicides are prohibited.Weeds should be pulled out carefully to prevent loosening of the cuttings.

8.4 TopdressingWhen new roots and new branches grow and new branches have 2-3 leaves that are normally expanded, 0.2%(mass ratio)potassium dihydrogen phosphate or water-soluble compound fertilizer(N∶P∶K=1∶1∶1)solution is applied once 10-14 d.After 5 months, 0.5%(mass ratio)water-soluble compound fertilizer(N∶P∶K=1∶1∶1)solution can be applied once every 2 weeks.The use of fertilizer should comply with the regulations of theRuleofRationalFertilization-General(NY/T 496-2010)[7].

8.5 Prevention and control of pests and diseases

8.5.1Principles of prevention and control.In accordance with the plant protection policy of "prevention first, comprehensive control", the harmless control principle of "agricultural control, physical control, biological control as the mainstay, and chemical control as the supplement" is adhered to.The use of pesticides for prevention and control should strictly follow the regulations of theGuidelineforSafetyApplicationofPesticides(GB/T 8321.9-2009)[8].

8.5.2Prevention and control methods[2].(i)Root rot.Root rot is a frequently-occurring disease, and occurs easily under conditions of high temperature and humidity.The roots of diseased cutting seedlings are dark brown, and the root bark is gradually decayed.The branches and leaves wilt until they die.In normal times, it is needed to strengthen the management of the nursery, ventilate and transmit light, and remove the accumulated water in the nursery in time to avoid water accumulation on the ground.Fertilizer and water management should be strengthened to enhance plant resistance.The seriously ill plants are promptly removed and disinfected with quicklime in situ.If pesticide is used to control the disease, in the prevention or early stage of the disease, 50% thiophanate methyl diluted by 1 000 times or 50% wettable powder diluted by 800 times are used to irrigate roots once every 7 d, and they are applied continuously for 2-3 times.75% fenaminosulf(Genfuning)soluble powder diluted by 500-1 000 times or 96% hymexazol liquid diluted by 3 000-6 000 times is sprayed once every 10 d, and they are applied continuously for 2-3 times.

(ii)Cutworm.Cutworm happens occasionally.The larvae damage the twigs, often biting off the shoots and eating the twigs, causing poor growth or death of the seedlings.Weeds in the nursery should be pulled out in time to reduce the feeding conditions of the larvae and the place where the adults lay eggs.The soil at the place where the seedlings are broken is dug, and the larvae is killed manually for 10-15 d.According to the herbal medicine ratio of 50∶1(mass ratio), 6% trichlorfon powder and fresh weeds are mixed to make poisonous weeds and pile them in various places in the nursery to trap and kill the larvae.90% trichlorfon liquid diluted by 800 times, 50% phoxim emulsifiable concentrate diluted by 800-1 000 times or 1.8% avermectin emulsifiable concentrate diluted by 1 000 times can be sprayed on the rhizomes.

8.6 Seedling temperingCutting seedlings that are 4-6 months old can be tempered in a planned way according to the growth situation.For the seedlings cultivated in an open field, the shed is uncovered for half a day, the arch shed is removed after 2 weeks.The seedlings cultivated in a greenhouse are placed in the open area.Nets will be exposed from 10:00 to 16:00 every day, and the nets will be uncovered at other times.After 2 weeks, the nets will be fully uncovered to temper the seedlings.

9 Transplanting seedlings from the nursery

9.1 Transplanting timeWhen cutting seedlings are more than 8 months old and can better adapt to the harsh environment, they can be transplanted from the nursery.

9.2 Seedling requirementsThere is 1 seedling in each bag, each with 1-2 new shoots.The new shoots are more than 30 cm long, and each plant has more than 8 first-grade roots.

9.3 Lifting of seedlingsIf there is a bottom penetration phenomenon 3 days before the lifting of seedlings, the roots should be cut to slow the seedlings.1 day before the lifting of seedlings, large water is needed to soak the seedbed; the branches and leaves are pruned to make the branches 30-40 cm long, leaving one leaf or not.When the seedlings are lifted, they are taken and laid down carefully to prevent the seedlings from being damaged.

9.4 QuarantineIt shall be implemented in accordance with the relevant regulations of the competent authority on the occurrence of important quarantine pests.

10 Packaging, labeling and transportation[9-10]

10.1 PackagingSince the seedlings are large and the branches are hard and brittle, in order to avoid the breakage of the stems and branches of the seedlings and reduce the evaporation of water during transportation, it is advisable to use good pressure-proof and windproof plastic frames, bamboo frames or foam boxes to pack them, and the quantity is determined by the size of the frames and the convenience of counting.

10.2 LabelingFor sales, a label should be attached to each package.The label should indicate the type of seedlings, the name of the variety, the suitable planting area and season of the variety, the producer and registered place, quality index, quarantine certificate number, seed production and operation license number,etc.

10.3 TransportationClean, pollution-free, odor-free, and non-mixed tools are used for transportation, and the seedlings are protected against sun, wind, rain, and pollution, so they are transported in the morning and evening when it is cool.

11 Archive records[9-10]

Detailed records of the measures taken in each link of nursery establishment, nursery bag preparation, germplasm source, propagation material collection and processing, cuttings, seedling management and transplanting seedlings from the nursery, and relevant responsible personnel are made, and seedling cultivation files are established and saved to ensure traceability.

12 Summary

The key to the above technical procedures for direct breeding of cuttage bag seedlings ofS.suberectusis that the seedling cultivation container must have appropriate space for the growth and development of the root system ofS.suberectus.The seedling substrate is mainly acid loam.Cuttings should be processed in time when they are fresh.Root rot should be prevented and fertilizer management should be strengthened during the seedling stage.The stems and branches should be protected to avoid breaking during transportation.