Ministry of Agriculture Issues 2014/2015 Technical Guidance on Winter Rapeseed Production

Oil Crops Expert Steering Group of the Ministry of Agriculture

National Agricultural Technology Extension Service Center

This year's summer-harvested rapeseed continued to increase and once again hit a record high. The meteorological department predicts that, affected by an El Nino event, low temperatures and continuous rain may occur in the Yangtze River Basin in autumn, while the harvest period of the preceding rice crop will be delayed, which will adversely affect timely sowing and transplanting of rapeseed. In order to effectively implement key technical measures for rapeseed disaster prevention and mitigation, and go all out to secure a bumper rapeseed harvest next year, the Oil Crops Expert Steering Group of the Ministry of Agriculture, together with the National Agricultural Technology Extension Service Center, studied and put forward the 2014/2015 Technical Guidance on Winter Rapeseed Production.

1. Select suitable varieties and promote high-yield, high-efficiency technical models

All localities should, in light of resource conditions, cropping systems and production realities, select new “double-low, three-high” varieties (low erucic acid, low glucosinolate; high yield, high efficiency, high resistance) suited to local conditions, and support them with high-yield, high-efficiency cultivation technical models such as plowed direct seeding, furrow-opening broadcast (direct) seeding, and seedling raising and transplanting. In double-cropping areas, where the technical models of mechanized rice-rapeseed direct seeding, rice-rapeseed furrow-opening broadcast seeding, or dryland relay (direct) seeding are adopted, medium-maturity varieties should be selected that are resistant to sclerotinia stem rot, tolerant to waterlogging, tolerant to dense planting and resistant to lodging; where the technical models of relay transplanting in cotton fields or transplanting in rice fields are adopted, medium (late) maturity varieties should be selected that are resistant to sclerotinia stem rot, resistant to lodging, strong in individual development and ultra-high-yielding. In rice-rice-rapeseed triple-cropping areas, where direct seeding is adopted, early-maturity varieties should be selected that are resistant to sclerotinia stem rot, strongly resistant to lodging, cold-tolerant, and do not bolt or flower early; where seedling raising and transplanting is adopted, medium-early maturity varieties should be selected. In view of the trend in recent years of high incidence and severe damage of sclerotinia stem rot in rapeseed, attention should be paid to selecting rapeseed varieties with low susceptibility or a higher level of resistance to sclerotinia stem rot, so as to prevent the disease at the variety level.

2. Increase sowing density and sow early while there is moisture to ensure a full stand

Timely early sowing and increased density of winter rapeseed in the Yangtze River Basin are the key to achieving high yields. Because the growth period of the preceding rice crop is delayed, it is necessary to seize moisture and sow or transplant rapeseed early, and strive for a full stand from a single sowing. For double-croppingdirect-seeded rapeseed, after the preceding rice and other crops are harvested, generally from September 20 to October 15, use methods such as mechanized combined sowing, furrow-opening no-till direct seeding, or mechanized tillage with manual broadcast seeding, and sow while there is suitable soil moisture, with a sowing rate of 250-300 grams per mu and a density of about 30,000 plants per mu. When moisture is poor, irrigate once after sowing to ensure a full stand from a single sowing. For plots where sowing is delayed and moisture is poor, the sowing rate should be increased by about 20%. For double-cropping transplanted rapeseed, the optimal seedling-raising period and transplanting period are around mid-September and mid-October respectively; the ratio of seedbed to main field should preferably be 1:6, and the seedbed sowing rate is generally 500-600 grams per mu. During transplanting, “two plants per hole” may be used to ensure a field planting density of 6,000-8,000 plants per mu. For early-maturity rapeseed under the rice-rice-rapeseed triple-cropping system, direct seeding is generally carried out in late October after the late rice is harvested, using mechanized combined sowing, mechanized furrow-opening direct seeding, or reduced/no-till direct seeding to sow while there is moisture, with a sowing rate of 300-400 grams per mu and a density of more than 40,000 plants per mu; for seedling raising and transplanting, the seedling-raising time may be about 1 week later than that of medium-maturity rapeseed varieties, and transplanting should be done in a timely manner after the late rice is harvested.

3. Strengthen field management and carry out good prevention and control of diseases, insects and weeds

Great importance should be attached to integrated control of sclerotinia stem rot; on the basis of selecting resistant varieties, reduce the damage of sclerotinia stem rot by strengthening field management. First, open the three ditches well. Rapeseed in rice fields in the Yangtze River Basin is prone to waterlogging, which aggravates the occurrence of sclerotinia stem rot. When sowing or transplanting, the waist ditch, bed ditch and surrounding ditch should be opened well and cleaned up in a timely manner to keep the three ditches unobstructed. Second, thin and fix seedlings in a timely manner. For direct-seeded rapeseed, drill sowing is recommended; for manual broadcast seeding, seedlings are generally thinned and fixed after the 2-3 leaf stage to prevent excessive density and poor ventilation and light penetration from aggravating the occurrence of sclerotinia stem rot. For precision mechanical direct seeding, seedling thinning and fixing may be unnecessary. Third, continue to promote“one promotion and four preventions”. The early flowering stage is the best period for controlling sclerotinia stem rot and flower sterility. Generally, per mu, mix 100 grams of 40% dimethachlon wettable powder or prochloraz plus 100 grams of potassium dihydrogen phosphate plus 50 grams of quick-acting boron in one application, and apply with a motorized sprayer (mixed with 15 kg of water) or a manual sprayer (mixed with 30 kg of water). In addition, attention should also be paid to controlling weeds and insect pests at the seedling stage. For transplanted rapeseed before transplanting and for direct-seeded rapeseed after sowing but before emergence, 50-75 grams per mu of 50% acetochlor emulsifiable concentrate mixed with 50 kg of water may be sprayed for closed weeding. For seedling-stage weeds, selective herbicides such as clethodim and quizalofop-p-ethyl mixtures, Shuangzhu, and Youcao Shuangk e may be used. Rapeseed seedlings are also susceptible to damping-off, cabbage caterpillar, underground pests and other damage, and should be controlled in a timely manner before the 3-leaf stage. For damping-off, 75% chlorothalonil 1000-fold solution may be sprayed on seedlings and soil; for cabbage caterpillar, 3% acetamiprid emulsifiable concentrate 1000-fold solution or 12.5% cyfluthrin suspension concentrate 10000-fold solution may be used for control.

⟦NL> 4. Fertilize scientifically to promote robust plant growth

Fertilizer and water regulation should be strengthened to cultivate strong seedlings and ensure safe overwintering. According to the growth characteristics of rapeseed and its fertilizer requirements, basal fertilizer should be applied heavily, topdressing should be scientific, and boron fertilizer should be increased; the application of rapeseed-specific slow-release formula fertilizer is recommended. For transplanted rapeseed, per mu, 10-12 kg of pure nitrogen (N), 3-4 kg of phosphorus (P2O5), 3-5 kg of potassium (K2O), and 0.75 kg of borax may be applied; of this, 60% of the nitrogen fertilizer, 60% of the potassium fertilizer and all of the boron fertilizer are applied as basal fertilizer, another 20%-30% of the nitrogen fertilizer is applied as overwintering seedling fertilizer, and 10%-20% of the nitrogen fertilizer and 40% of the potassium fertilizer are applied as stem-elongation fertilizer. For direct-seeded rapeseed, per mu, 9-11 kg of pure nitrogen (N), 3-4 kg of phosphorus (P2O5), 4-5 kg of potassium (K2O), and 0.75 kg of borax may be applied; of this, 50% of the nitrogen fertilizer is applied as basal fertilizer, 20% as seedling-promoting fertilizer, 20% as overwintering seedling fertilizer, and 10% as stem-elongation fertilizer; 80% of the potassium fertilizer is applied as basal fertilizer and 20% as overwintering seedling fertilizer; all of the phosphorus fertilizer and boron fertilizer are applied as basal fertilizer. For rapeseed with excessive growth, 30-40 grams per mu of 15% paclobutrazol mixed with 40 kg of water may be sprayed to control vigorous growth and promote sturdy growth, thereby improving the cold resistance of rapeseed.

5. Integrate agricultural machinery and agronomy to advance full-process mechanized production

Vigorously promote the demonstration and extension of full-process mechanized rapeseed production technology, integrating core technologies such as suitable soil moisture management, mechanized varieties, increased planting density, one-time application of slow/controlled-release complete-nutrition fertilizer, combined mechanical sowing, pre-emergence closed weeding, “one promotion and four preventions”, mechanical harvesting, and rapid decomposition of straw (sclerotia), and explore new mechanized and scaled production models such as transfer of idle winter farmland and services by agricultural machinery cooperatives, so as to continuously improve the availability and adoption rate of mechanized rapeseed production technology. For ordinary varieties, the two-stage harvesting technology of mechanical (or manual) swathing and mechanical threshing is generally used. When more than 80% of the siliques in the whole field are loquat-yellow, use a rapeseed swather (or manual labor) to cut down the rapeseed, leave it to dry in the field for 5-7 days, and then use a self-propelled pickup thresher for pickup threshing. For varieties with relatively good resistance to pod shattering, suitable plant height, upright plants, neat silique layer and good maturity uniformity, the mechanical combine harvesting technology may be used. When more than 90% of the siliques in the whole field are loquat-yellow and the grain moisture content is 15%, use a rapeseed combine harvester for one-time harvesting. After harvesting, seize fine weather to dry the rapeseed until the moisture and impurities are below 12%, so as to ensure safe storage.