Germination Characteristics and Secondary Metabolism Regulation of Scutellaria baicalensis Georgi Under Osmotic Stress with PEG

Jinhua LIU Qian LIU Jia LI Yongqing ZHANG

AbstractGroundnut, also known as peanut, has high economic and medicinal value. A member of the legume crops, it is rich in various nutrients and is one of the main oil crops for processing highquality edible oil. Compared with other cash crops, planting peanuts can bring greater economic benefits to farmers. In this paper, we summarized techniques of cultivating spring peanut in open fields for years, and explored the problems and difficulties in the cultivation management process, in order to provide technical guidance for the farmers to carry out highyield spring peanut production.

Key wordsSpring peanut; Cultivation; High quality; High yield; Technique

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Received: November 23, 2018Accepted: December 25, 2018

Supported by the Major Scientific and Technological Project of Henan Province (16100111000); the Special Fund for the Construction of Modern Agricultural Industry Technology System of Henan Province (SPAD01205G01).

Ruhong FU (1965-), male, P. R. China, associate researcher, devoted to research about peanut breeding and physiological cultivation.

* Corresponding author.

Spring planting in open field is one of the main planting patterns for peanuts in China, and it accounts for a considerable proportion in the main peanut production areas in China. In recent years, the spring mulching cultivation technology has been widely popularized and applied, but the open field cultivation still has great development potential for its simple operation, low technical requirements, time and labor saving, low investment and low cost. On the other hand, farmers still have certain technical problems in the cultivation of spring peanuts in the open field. In this paper, exploration was made to the problems from the cultivation and management based on the summary of the technical experience from years of spring peanut cultivation in open field, so as to provide the vast majority of farmers with technical references for the highyield cultivation of spring peanuts.

Land Preparation

Peanut is an economic crop that blooms on the ground and bears fruits under the ground after forming the fruit needles. It is forms a fruit needle and drills into the ground. Peanuts grow best in light, sandy loam soil and oil sand soil［1］. The plots for planting peanuts should be performed with ploughing under to great depth, and in the meantime, 30-40 t of highquality farmyard manure per hectare should be applied with the ploughing. Where conditions permit, the plots can be irrigated first, and then the manures and chemical fertilizers can be applied to the furrows, which are then ridged for timely sowing. It should be noted that peanuts prefer single cropping to continuous cropping and alternate cropping. The best preceding crops are corn, millet and sorghum.

Cultivated Varieties

Good varieties are the basis for high yield. The growth period for peanuts is about 110-120 d. Seeds should be the pods with full fruit, uniform shape and no broken surface. Before removing the shells, the pods should be dried for 1-3 d, and then the grains with pure color and uniform shape are selected as the seeds.

Seed preparation before sowing. Before sowing, it is necessary to select seeds. Seed selection can effectively improve the survival rate of peanuts, thereby realizing full stand of seedlings and uniform emergence. First, the peanut seeds should be dried. On the one hand, it can greatly shorten the emergence time after sowing, and on the other hand it can increase the per unit yield of spring peanuts. The time for seed shelling should not be too early, nor too late, otherwise it will reduce the germination rate of seeds. Seed dressing should be carried out before sowing. The seed dressing should be based on the planting environment and common pests and diseases of peanuts. For the fields more prone to have diseases, carbendazim wettable powder can be used for seed dressing, and for the field more prone to have pests, phoxim emulsion can be used. In order to ensure that the seeds grow robust after budding, the seed coating needs to be completed within 10 h before sowing to provide sufficient time for the surface of the agentcoated seeds to be airdried.

Scientific Fertilization

Peanuts are tolerate to poor soil, so fertilization should be based on base fertilizer (30 t of manure per hectare) and assisted with phosphate fertilizer (150-200 kg of diammonium phosphate per hectare). When the peanuts are planted in poor soil, 100-150 kg of urea should be applied per hectare. Separated layer fertilization: the fertilizers before sowing should be divided into 2 layers of base fertilizer and seed fertilizer. Split fertilization: the fastacting nitrogen fertilizers should be applied separately in the combination of base fertilizer, seed fertilizer and topdressing. The fastacting nitrogen fertilizers are mainly applied as the base fertilizer and seed fertilizer, but a certain amount of urea or other fertilizers can be applied in a timely manner as topdressing fertilizers if there is any fertilizer insufficient phenomenon. Deep fertilization: the base fertilizer should be applied to 8-10 cm under the seeds, and the seed fertilizer should be 3-5 cm, while the dressing depth should be reach 10 cm or more.

Timely Sowing and Rational Close Planting

The suitable sowing date of peanuts in this producing area is in the early and middle of May. The specific sowing time depends on the weather conditions based on the principles as follows: as long as the surface temperature of 5 cm is stable and over 12℃, then the peanuts can be planted with 304 grains per hole covered with 3-5 cm of soil. On the other hand, hillseeding is performed after land preparation. If the soil moisture is not enough, the peanuts must be planted with water. In the way of planting with water, fertilization, sowing and soil covering must be conducted after the water is completely infiltrated.

Peanuts should have seed soaking before sowing. The seeds should be soaked for 3-4 h using warm water (cool to boiled water of 2∶1) to preserve moisture, and then the seeds are sealed and placed at 20-25℃ for accelerating germination, where buds can be germinated after a day and night. The seeds should be sown in wet soil so as not to dry the bud［2］. Seeds that are germinated should be sown in no time and should not be left overnight to prevent the buds from being too long and damaging the germs. Generally, the seeds should be sown sparsely in fertile land and thickly in poor soil. The proper planting density in the study area is 15×104-20×104 plants/hm2, and the suitable seeding density of each plot should be determined according to the soil fertility and the density tolerance of the peanut variety.

Peanut Field Management

Filling and thinning seedlings: the growth of the seedlings should investigated as early as possible from late May to early June to carry out timely seedling filling to the plots with obvious seedling missing. The seedlings can be filled using the accelerating germination planting with water. In the meantime, it should also complete the thinning and final singling of seedlings. Seedling hardening: when the peanuts are out of the seedlings, the soil at 2 cm around the seedling is removed by hands, and then the 2 cotyledons are pulled out of the soil surface using hands. Seedling hardening is usually conducted 3 d after the first seedling hoeing. Timely seedling hoeing and filed tripping: the hoeing should be begun once the seedlings grow out of soil, and the first field tripping should be done 3 d after the hoeing. The second tripping should be 15-20 d after hoeing, and attention should be given to the ridging, which should not above the seedlings. Field tripping should be done 3 times before the flowering season ends. When the ridge is closed, the square ridge is tripped to make it easy for the fruit needles insert into the soil. In the meantime, large grass should be removed.

There are differences in the water requirements of peanuts at different growth stages. ① Seedling period: The management focus of this period is to promote the shortness of the peanuts and the deep rooting of the roots. Therefore, it needs to control the number and the amount of watering, try not to reduce the watering time and amount and avoid fertilization, so as to create a relative dry soil grow environment to achieve the purpose of dryfeeding roots. ② Podpin period: This period is the watershed of peanut water demand. The management focus at this time is to ensure the soil is moist, promote plant growth and the deep rooting of pod pins. Therefore, it needs to ensure the supply of water and fertilizer to ensure the soil is moist. ③ Pod bearing period: It is the key period for the growth and development of peanut pods. At this time, the demand for water in peanuts reaches a maximum. The management in this period is to recycle the water for frequent irrigation, so as to ensure the demand for moisture, which can also prevent excessive water from causing various diseases including pod rot. ④ Fruitfilling period: During this period, peanuts are mainly in reproductive growth, when the root absorption capacity is decreased and the leaves turn yellow and fall off. In order to prevent premature senescence of the plants, promote fruit enlargement and increase yield, the management focuses of this period are: light watering, applying 150 kg/hm2 of the fastacting fertilizer with water, and spraying the foliar fertilizer such as potassium dihydrogen phosphate.

Peanut Seedling Management

Growth characteristics of seedlings and central tasks for management

From the emergence to the beginning of flowering is the seedling stage of peanuts, which is around a month depending on different varieties and environmental conditions. Peanut seedling stage is the main stage of vegetative growth, and it is also a period of effective flower bud differentiation. The growth characteristics of this period are that the aboveground part grows slowly and the roots stretch rapidly, and the nutrients produced by the plant are mainly used for root development and flower bud formation. In this period, due to the small trophic body, too much fertilizer and water will lead to the excessive growth of stems and leaves, affecting root development and flower bud formation. Therefore, the key task of seedling management is to properly control the growth of the aboveground part on the basis of ensuring the growth of seedlings, so as to make the plants strong but not prosperous. Thereby, the seedlings are strong, the stems are thick, the branches are dense, the knots are dense, and the roots are developed, which can facilitate the formation of a large number of flower buds, creating conditions for the blooming of flowers.

Seedling management measures

When the seedlings reach full stand, it needs to check the seedlings comprehensively. If there are missing seedlings, it should carry out promptly germination or replanting. The seedling hardening of peanuts is to remove the soil around the seedlings to make the 2 cotyledons exposed to the ground. The reason why seedling hardening can increase the yield is that it liberates the first pair of side branches and gives full play to their advantages. After seedling hardening, the 2 cotyledons are exposed to sunlight, which can make the stems thick and the nodes short, followed by the fastgrowing of the first pair of lateral branches and secondary branching, and early flower buds differentiate early, which are beneficial to early flowering, uniform flowers, full and abundant fruits. The results are that the effective branching interval is shortened by 0.26 cm, the fruit bearing is concentrated, the fruit filling rate is increased by 12.3%, and the fruit weight per plant is increased by 14.3%. Moreover, seedling hardening can also promote the growth of roots. The roots grow deep into the soil, and the number of lateral roots also increase, thereby enhancing the drought resistance and water and nutrient absorption of the plants. In addition, seedling hardening can remove the herbaceous roots, which is conducive for the fruit needles to root deep in soil, and it also changes the microclimate at the base of the plant. The base tissues of the lateral branches are robust and stable, which is not conducive to the growth and reproduction of aphids, thereby reducing the damage of aphids during seedling stage. The time of seedling hardening is appropriate when the seedlings are basically completed. If the time is too early, the young seedlings are tender and weak, and if the time is too late, the first pair of side branches are buried in the soil for too long and becomes weak. During seedling hardening, it should first break the ridges using bighoe, and then harden the seedling using spuds. The depth depends on the appearance of the location of cotyledon. Since the seedling emergence of peanuts is not uniform, seedling hardening should be carried out in batches.

Tillage, weeding and deep hoeing

The intertillage during the seedling stage of peanut can eliminate weeds, loosen soil, increase ground temperature, improve soil aeration［3］, and regulate soil moisture, which plays an important role in promoting root development, root nodule formation and seedling growth. The tillage should be done deeply into soil. From the emergence of seedlings to before the flowering of peanuts, the land should be deeply ploughed 2-3 times according to the soil moisture. Deep tillage can let out moisture and improve temperature in wet land, and preserve moisture and prevent drought in dry land. It can promote the deep rooting of main roots, differentiation and growth of lateral roots and development of fruits, which can lay the foundation for the robust growth and development of plants and flowers. In order to avoid burying the seedlings and covering the branches during the tillage, the plot remains the state after seedling hardening, so as to protect the normal growth of fruitbearing branches and nodes at the base. Although peanuts need few fertilizers during the seedling stage, fertilizers should be applied according to the growth conditions if the base fertilizer is insufficient.

Ruhong FU et al. Cultivation Techniques for Highquality and Highyield Spring Peanut in East Henan Province

Pod and Fruit Management

Fertilizers such as potassium dihydrogen phosphate (suitable concentration of 0.3%) and plant growth regulators can be sprayed to the leaves in a targeted manner according to the growth conditions to promote the formation of kernels.

Pest Control

During the whole growth period, peanuts are susceptible to root rot, leaf spot and rust diseases. The most susceptible insects are aphids, grubs and red spiders. Pest control for peanuts generally requires 3 pesticide applications, which go specifically as follows:

In the emergence stage, it can achieve good control effect on the leaf spot disease, root rot, stem rot and aphids by spraying the1 000-2 000 times diluted 50% isothioate+800-1 000 times diluted 38% oxadixyl anchor azoxystrobin, or 1 000 times diluted 40% omethoate+1 000 times diluted 50% carbendazim［5］. At the beginning of flowering period, it can effectively control the viral diseases, net blotch, aphids and bollworms on peanuts by spraying 500 times diluted Kangkuning solution+350 mL/hm2 of 2.5% highefficiency cyhalothrin vinegar emulsifiable concentrate+450 kg of water, 1 000-1 500 times diluted 40% chlorpyrifos+800 times diluted bistriazole triolol. During the pod expanding stage of peanuts, it can achieve good effects on controlling the brown spot, black spot and leaf spot diseases of peanuts by spraying the 3 000 times diluted 96% Tianda carbendazim. The underground pests can be controlled by spreading the mixture of 10% chlorpyrifos granules with fine soil to the ground.

Timely Harvest

Peanuts can be harvested when the leaf color turns yellow and some stem stems and leaves are dry, usually in midSeptember. After harvesting, the peanut pods should be airdried to promote postripening and improve seed maturity［4］. Peanuts for seed reserving must be harvested and dried before the frost.

References

［1］ SONG YL, LI J, LI Y. Highyield cultivation techniques of Peanut［J］. Modern Agricultural Science and Technology, 2013(8): 69-73.

［2］ LI Q. Key measures for peanut planting and management［J］. Henan Agriculture. 2018(10): 106-108.

［3］ GAO YH. Discussion on highyield cultivation techniques of peanuts［J］. Agriculture and Technology, 2018(16): 117-118.

［4］ HONG SM. Discussion on highyield and highquality cultivation techniques of spring peanuts［J］. Friends of Farmers, 2015(16): 145-146.

Editor: Na LIProofreader: Xinxiu ZHU