Huisong ZHANG, Guoxian SONG, Zhanggui HAN, Yuxiao HUANG, Jinsong ZOU

Qinzhou Institute of Agricultural Sciences, Qinzhou 535000, China

Abstract Sea red rice is a geographical indication agricultural product of Qinzhou City. It is suitable for growing in hydrochloric acid field with salinity of 2‰-20‰, and is a green and healthy food positioned in the medium and high-end rice market. The brand of Qinzhou sea red rice started to be established in November of 2019. In this paper, the technical specification for seed production of Qinzhou sea red rice is introduced from the aspects of seed production, breeding and harvest, so as to provide technical support for accelerating the popularization of characteristic varieties and the process of industrialization.

Key words Qinzhou sea red rice, Chihe, Seed production, Technical specification

1 Introduction

Qinzhou sea red rice is commonly known as "Chihe" and "Chaohe", and mainly grows in coastal beach zone, with strong feral property. It is rich in a variety of trace elements, vitamins, dietary fiber and other nutrients, anthocyanins, flavonoids and other effective substances to increase immunity. It is a nutritious and healthy food positioned in the medium and high-end rice market. In September of 2019, it obtained the registration certificate of geographical indications of agricultural products by the Ministry of Agriculture and Rural Areas.

Qinzhou is close to Beibu Gulf, and coastline reaches 1 478 km. It possesses 9 533 ha of intertidal zone, and the area of salted acid field is 6 667 ha. Unique climate environment, location advantages and good mass planting foundation have laid a solid basis for the industrialization of Qinzhou sea red rice.

Industrial development planning of Qinzhou sea red rice during 2020-2022 is made in Qinzhou City. In combination with relevant policies for poverty alleviation, it strives to cultivate Qinzhou sea red rice into an important industry for enriching the people and strengthening the city. With the increasing production demand of Qinzhou sea red rice, its seed production quality has become the key link of variety promotion. Therefore, the technical specification of Chihe seed production is summarized to provide scientific and technical support for accelerating the industrialization process of "Qinzhou sea red rice".

2 Scope of application

This standard specifies the terms and definitions of Chihe seed production technology, as well as the breeding and harvesting technology of production seeds. It is applicable to the breeding of Chihe production seeds in Guangxi.

3 Normative references

The rule of GB/T 1.1-2009 is cited in this standard. For the following dated documents, only the dated version is applicable to this standard. For undated documents, the latest edition (including all amendments) is applicable to this standard.

GB/T 3543 (All Parts)RulesforInspectionofCropSeeds; GB 4404.1GrainCropSeedsPart 1: Cereals; GB/T 7415CropSeedStorage; GB/T 8321 (All Parts)GuidelinesforRationalUseofPesticides; NY/T 394GreenFoodFertilizerUseGuidelines; NY/T 5010Pollution-freeAgriculturalProductsEnvironmentalConditionsofProducingAreasofPlantingIndustry.

4 Terms and definitions

4.1 ChiheIt is cultivated in the coastal beach area with rich mud, and the rice grains produced are reddish red to light reddish red, with smooth lines and taro flavor after cooking, and are chewy. It is a conventional photosensitive late rice variety rich in dietary fiber and trace elements. In Qinzhou, it is also called Chaohe, Maohe or sea red rice.

4.2 Effective soil layerThe soil thickness required for the normal growth and development of plant roots.

5 Breeding of production seeds

5.1 Origin environmentThe coastal beach area with rich silt is selected, and effective soil layer is more than 45 cm. Soil pH is between 4.3 and 6.5, and salinity is between 2‰ and 20‰. Environmental quality of other producing areas should correspond with the stipulation of NY/T 5010.

5.2 Seed qualityIt should correspond with the stipulation of GB 4404.1.

5.3 Sowing and seedling raising

5.3.1Sowing time. It is suitable for sowing from early June to early July.

5.3.2Seed consumption. Seed consumption per mu in the field is between 3 and 4 kg.

5.3.3Seedling field selection. The fields with relatively high and open terrain should be selected, which can build flood control and damp proof sluice gates, have no quarantine diseases and pests, have convenient drainage and irrigation, and are not directly soaked by the tide.

5.3.4Seedling field pretreatment. In the places with more fishes, shrimps and crabs, fence can be used or ducks can be released 2-3 d in advance to pick up fishes, shrimps and crabs before sowing.

5.3.5Land preparation and application of base fertilizer. Ploughing and land preparation should be conducted 2-3 d before sowing, and ploughing depth is between 15 and 20 cm. When preparing the land, sufficient rotten farmyard fertilizer is applied, and commercial organic fertilizer can also be used as base fertilizer. 12 000-15 000 kg of well-rotted farmyard manure or 675-750 kg of commercial organic fertilizer is applied in seedling field per ha, and it should plough and rake twice, to rake rotten and level. The application of fertilizer should correspond with the requirement of NY/T 394.

5.3.6Border raising. Border is raised according to 120-130 cm of border width, 15-20 cm of border height, and 30-40 cm of ditch width.

5.3.7Seed treatment. (i) Drying seed in the sun. In a sunny day, the seeds are put on dustpan and other instruments to evenly spread, and seeds should be dried for 3-5 h. (ii) Seed selection. The rice seeds are soaked in clear water. After fully stirring, the floating chaff, diseased rice and sundries are removed, and the rice seeds with full grains are selected. (iii) Seed soaking and disinfection. After seed selection, 2 500-3 000 times diluent of 25% prochloraz EC or 300-500 times diluent of 40% trichloroisocyanuric acid or 500 times liquid medicine of 50% carbendazim is used for seed soaking and disinfection for 6-8 h. After that, the seeds are fished out and washed with clean water. Then the seeds are soaked with flowing water, and seeds are soaked for 48-72 h below 20 ℃, 30-48 h between 20 and 25 ℃, 24-30 h more than 25 ℃. The seeds are washed with water every 4-6 h. (iv) Germination. After seed soaking and disinfection, the seeds are picked up, and water is dripped dry. 40-45 ℃ of hot water is used to preheat for 3-5 min. After that, the seeds are put into net bags, and it is sealed with clean straw or gauze, towel,etc.After temperature of seeds rises, surface temperature of budding rice seed should be controlled between 30 and 32 ℃. When temperature is too high, it should timely carry out dump cooling. When temperature is lower than 20 ℃, 30-32 ℃ of warm water should be sprinkled every 3-4 h. After 10-15 h of germination, whitening and chest breaking, when the bud grows to half grain and the root grows to one grain, it is spread, and the bud is refined at room temperature for 3-6 h.

5.3.8Plate loading. 434-hole plastic plates are selected. Two plastic plates are placed horizontally on the border surface of each seedling bed, and there is no gap between each plate. The bottom of the plate is fully in contact with the ground surface and is not suspended. 50-55 seedling plates are required for each mu of field. Before placing the plate, 20-30 g/plate of seedling strengthening agent is evenly sprinkled on the ground surface. After placing the plate, the slurry is filled. After paving the holes, sowing is conducted, and 2-5 seeds are sown per hole. After sowing, the seeds are tapped and pressed with a broom[1].

5.3.9Seedling field management. (i) Covering net. After sowing, a sunscreen net is covered to prevent it from sun-proof and being washed by heavy rain. (ii) Water management. It should keep the bottom water of the seedling tray. When the soil surface turns white or the seedling leaves curl, it should spray water or pour water into the ditch to let the water penetrate into the seedling tray to avoid flooding. (iii) Uncovering net and refining seedling. When the seedling has one leaf and one heart, it uncovers the net and refines the seedling in sunny evening or cloudy morning, before light rain or after heavy rain. Water is replenished once on the day of net uncovering to keep the bed soil moist. (iv) Topdressing. In 5-7 d before seedling lifting, weak seedlings should be sprayed by 0.2%-0.3% of buffer stock solution or harmless dilute fecal water (biogas liquid) or 0.5%-0.8% of urea liquid. After spraying fertilizer, the leaves are washed with clean water.

5.4 Field management

5.4.1Isolation. The fields should be concentrated and contiguous, and there should not be other rice varieties heading and loosing pollen at the same time all around. If natural obstacles are used for isolation, the isolation distance shall be more than 200 m; if time isolation is adopted, the flowering period should be staggered for more than 30 d; if space isolation is used, the distance should be more than 700 m.

5.4.2Soil preparation. In 2-3 d before throwing seedlings and transplanting, ploughing and land preparation are conducted, and ploughing depth should reach 15-20 cm. It should plough and rake twice, to rake rotten and level.

5.4.3Transplanting. (i) Seedling age. The suitable seedling age for throwing seedling is 2.5-3.5 leaves, and for transplanting seedling is 3.5-4.5 leaves. (ii) Seedling choose. It should select short, strong, neat and uniform seedlings, with thick and flat stem base, no diseases and pests, no miscellaneous plants, green leaves, tangled roots and many white roots. (iii) Seedling transportation. The soft (hard) seedling tray shall be placed horizontally or roll seedling tray shall be stacked, and the seedlings shall be stacked in 3-5 layers. (iv) Density. Row spacing of artificial and mechanical transplanting seedlings should be between 30.0 and 33.0 cm, and row spacing should be between 27.0 and 30.0 cm; 8 000 -10 000 stumps should be threw and planted per mu. (v) Supplementing seedlings. It should check the seedlings and make up the deficiency within 3-5 d after throwing and transplanting seedlings, and make up the seedlings in time[2].

5.4.4Water and fertilizer management. (i) The paddy field with long sea tide immersion time and more times may not be fertilized. (ii) For paddy fields with short sea tide immersion time and less affected by sea tide fluctuation, 300-500 kg of commercial organic fertilizer shall be applied per mu before transplanting. (iii) 100-200 g of potassium dihydrogen phosphate is sprayed for 1-2 times during grouting period, and 30 L of water is mixed per mu. (iv) The water level can be effectively controlled according to the difference of tidal bearing degree in different growth stages of seedlings. In case of flood or high tide, the sluice gate could be closed to prevent the water level in the paddy field from being too high; if the water level in the paddy field is too high, the sluice gate shall be opened in time for drainage at low tide to reduce the water level in the paddy field. The water level control standards for each growth period of seedlings are as follows: (i) seedling rejuvenation stage: it is better to control the water level not being drowned; (ii) booting stage: controlling the water level below the flower bud; (iii) heading and flowering stage: controlling the water level below the flower ear; (iv) late maturity stage: water should be cut off and dried 10-15 d before harvest.

5.5 Impurity removal

5.5.1Seeding period. According to the height, color, leaf shape, drape angle and other botanical morphological characteristics of seedlings, miscellaneous plants are removed.

5.5.2Heading and flowering stage. The miscellaneous plants are removed by the difference of flowering period between early and late flowers and the botanical morphological characteristics of flower such as stigma, stamen and pollen.

5.5.3Maturity and harvest period. It should judge according to the shape and color of panicles and grains and the length of grain awns, and remove miscellaneous plants[3].

5.6 Main plant diseases and insect pests control

5.6.1Prevention principle. Prevention first, comprehensive prevention and control.

5.6.2Agricultural control. It should adopt reasonable farming system, and select Chihe varieties with high seed purity, maintain its stress, disease and insect resistance, and reduce the occurrence of diseases and pests.

5.6.3Chemical control. Pesticide use should correspond with the requirement of GB/T 8321 (All Parts).

(i) Main diseases. Sheath blight of rice: Jinggang·wax bud fungus, validamycin, andBacillussubtilisare used for prevention and control. Rice blast (leaf blast): 10% of tricyclazole and 20% of iprobenfos are diluted according to 500 times of liquid. Uniform spray for whole plant is conducted, and no drop is suitable, 1 times every 7 d, continuous spraying 2-3 times. When the condition is serious, the whole plant is sprayed evenly with 10% of tricyclazole, 20% of iprobenfos (70 mL) and water (15 L), 1 times every 7 d, and it should continuous spray for 2-3 times. (ii) Main pests. Rice-leaf roller: it is treated with drugs in the heyday of 2-3-instar larvae, and it is sprayed with 1.8% avermectin (225-450 mL) and water (900 kg) per ha. Yellow rice borer: in the early stage of hatching eggs, the fields with more than 750 eggs/hm2are controlled by drugs, and 1.8% avermectin (225-450 mL) mixing with water (900 kg) or three azophos (300 g) mixing with water 750 (kg) is used per ha. Plant hopper: 10% of imidacloprid (2.25 g) mixing with water (750 kg) per ha is used to pray the middle and lower parts of the rice plant. Rice thrips: when the curl rate of leaf tip is above 10% at the seedling stage, and the number of insects per 100 plants is 300-500, 405-540 g of insecticide or 2.25-3.00 g of imidacloprid mixing with 750 kg of water is used for spraying.

6 Harvest

6.1 Cleaning machines and toolsBefore harvesting, the harvester, basket and other harvesting tools shall be cleaned to ensure cleanliness.

6.2 Harvest(i) When more than 90% of the grains are yellow and ripe, they should be harvested in time on sunny days. (ii) During manual harvesting, 8-10 plants can be bound and harvested at a distance of 20-25 cm from the ear of rice.

6.3 DryingThreshing and grain drying shall be carried out in a closed and clean sun farm, and drying shall not be carried out on asphalt pavement, soil ground or places with serious dust pollution.

6.4 Seed quality inspection and quarantineIt is implemented according to the stipulation of GB/T 3543 (All Parts).

6.5 WarehousingThe seeds with full grains, no diseases and insect pests, no pollution and no miscellaneous grains are selected with the cleaning machine, and they are put into storage in time.

6.6 StorageThe seeds are stored in a ventilated and dry place to prevent mixing, moth, mildew, rats, birds and other hazards. It is implemented according to the stipulation of GB/T 7415.