Analysis of the Current Status of Ratoon Rice Planting and Recommendations for Moderate Development
1. Ratoon rice planting situation in 2014-2015
Ratoon rice production in Anqing City, Anhui Province began in the 1980s, but because there were no relatively suitable varieties with strong ratooning ability, research and extension of ratoon rice technology gradually decreased and eventually stalled. Starting in 2010, the agricultural technology departments of Anqing City again began ratoon rice technology research. Because the relatively good variety Zhunliangyou 608 with strong ratooning ability was selected, the planting area developed again. According to surveys and statistics by the agricultural department, in 2014, the city's ratoon rice planting area was 10,090.8 mu, the main season rice yield per mu was 504.22 kg, the average ratoon season yield per mu was 189.2 kg, and the two-season yield per mu reached 693.42 kg, an increase of 153.5 kg per mu compared with fields planted with single-season rice, an increase of 28.43%; it was slightly lower than the yield per mu of double-season rice, generally about 100 kg less per mu. However, the planting benefit was somewhat higher than that of double-season rice. In terms of planting areas, there were four counties and cities with areas exceeding 1,000 mu: Zongyang County 4,000 mu and Tongcheng 5,120 mu; Qianshan County 1,050 mu; Wangjiang 2,320 mu. Tongcheng City had an area exceeding 5,000 mu. In terms of selected varieties, Zhunliangyou 608, Wandao 187, Longliangyou No. 7, Anyuzao No. 1, Zaoxian 788, You I 608, Jinyou 207, Shenliangyou 5814, Y Liangyou No. 1, Liangyou 6326, Fengliangyouxiang 1, and Xinliangyou 223, although there were many varieties, the planting areas were not large. Only four varieties exceeded 1,000 mu: Zhunliangyou 608, Anyuzao No. 1, You I 608, and Y Liangyou No. 1. The largest area was Zhunliangyou 608, reaching 4,620 mu, accounting for 45.78% of the ratoon rice area, followed by You I 608 and Y Liangyou No. 1, each with an area of 1,700 mu.
2. Specific examples of ratoon rice planting
2.1. 2013 Wangjiang County Yutian Planting Professional Cooperative. In 2013, Wangjiang County Yutian Planting Professional Cooperative conducted a trial demonstration on 70 mu in Huangjiayan Village, Changling Town. The actual harvested average yield of early rice from 9 households was 540 kg per mu; the effective panicles per mu of ratoon rice reached more than 220,000, with an average of about 78 grains per panicle, and the actual harvested average yield per mu was more than 328 kg; provincial experts conducted on-site yield measurement and acceptance on two typical fields planted by Jin Qitian, and the two-season yield per mu reached 925.9 kg.
2.2. 2013 Tongcheng City Fengming Company. In 2013, the actual harvested yield per mu of main season rice was 640.5 kg, the yield per mu of ratoon rice was 182.6 kg, and the two-season yield per mu was 823.1 kg. Compared with his single-season rice yield of 500 kg per mu plus wheat yield of 200 kg per mu, totaling 700 kg per mu, this was 123.1 kg more, an increase of 17.59%.
2.3. 2014 Wangjiang County Yutian Planting Professional Cooperative. A trial demonstration plot of 100 mu was established in Huangjiayan Village. On August 1, Comrade Sheng Minyuan, Director of the Wangjiang County Administrative Service Center (formerly the Science and Technology Bureau), I, and technicians from the Wangjiang County Planting Industry Management Bureau and the Changling Town Agricultural Technology Station conducted yield measurements on typical fields in Huangjiayan Village. High-yield fields reached 650 kg, and the average yield per mu was about 600 kg. A random theoretical yield measurement was conducted on Zhunliangyou 608 mechanically raised and transplanted by Jin Sanyi, a household in the demonstration plot of Huangjiayan Village, Changling Town: 184,700 effective panicles per mu, an average of 150.5 grains per panicle, seed setting rate 81.2%, calculated at a 1,000-grain weight of 30.0 g, theoretical yield 677.1 kg/mu, and at 85% discount 575.6 kg/mu. In addition, field No. 3 of Jin Qitian's household, 1.99 mu of Zhunliangyou 608, was randomly selected for full-field mechanical harvesting, yielding 1,405.5 kg of fresh grain, with measured moisture of 33.2%, converted net to standard moisture (13.5%), the yield per mu was 545.4 kg; the average yield per mu of the two fields was 560.5 kg/mu. On August 16, Li Zefu, Director of the Provincial Rice Research Institute, and Niu Yunsheng, Director of the Provincial Planting Industry Bureau, led relevant experts from the Provincial Academy of Agricultural Sciences and the Provincial Agricultural Commission to Wangjiang County for actual harvesting, and the results were also gratifying.
2.4. The 20-mu ratoon rice demonstration plot in Qingcao Town, Tongcheng City. Field No. 3 of the demonstration plot, 2.42 mu of Zhunliangyou 608, was randomly selected for mechanical harvesting, yielding 1,657.1 kg of fresh grain, with measured moisture of 24.66% and impurities of 1%, converted net to standard moisture (13.5%), the yield per mu was 590.4 kg. Because September had already arrived at that time, the risk of harvesting the ratoon season increased. We recommended immediately applying 10 kg each of urea and 45% ternary compound fertilizer per mu after harvest as a bud-promoting fertilizer, strengthening pest and disease control, and at the same time paying attention to preventing damage from the "cold dew wind" to ensure a harvest in the ratoon season. The planting method was manual sowing and mechanical transplanting, and the variety was Zhunliangyou 608. Under the unfavorable conditions of excessive rain and insufficient sunlight during this year's rice growth period, field management was strengthened to overcome the effects of climate disasters. At present, field growth is uniform, with green stems and yellow grains, and basically no damage from pests, diseases, or weeds. On September 4, 2014, the Anqing City Science and Technology Bureau and the Tongcheng City Science and Technology Bureau jointly organized relevant experts to conduct an on-site inspection of the main season rice in the Qingcao Town demonstration plot of the project "Ratoon Rice High-Yield Cultivation Technology Trial Demonstration" implemented by Tongcheng City Fengming Agricultural Science and Technology Circular Company, and selected representative fields for acceptance.
2.5. Xuan Yibin of Yueshan Town, Huaining County. The effective panicles in the ratoon season reached about 200,000, with large panicles and small panicles accounting for 62.4% and 37.6% respectively. Among them: unpressed rice stubble produced an average of 1.2 panicles per stubble, with 73.5 grains per panicle; pressed rice stubble produced 1.7 panicles per stubble, with 31 grains per panicle. The average was about 57.52 grains per panicle, theoretical yield 224.33 kg per mu, and after an 85% discount, 190.7 kg per mu.
3. Analysis of ratoon rice yield and benefit
Farmers farm with economic benefit at the center: they plant whatever makes money, and plant it in whatever way makes money. Therefore, everything revolves around increasing income when farming. From the country's perspective, the country takes food security as its first priority. Therefore, the country does everything possible to encourage farmers to grow more grain and grow good grain. Therefore, as a functional department of the government and as a technical guidance unit for farmers' farming, we believe that only by finding the balance point between increasing production and increasing income, ensuring national food security, and ensuring increased farmers' income, can this be the premise for the promotion of grain crop varieties and technologies, and neither can be neglected. Accordingly, if ratoon rice can be promoted, there should be no problem with the main season rice yield, and the yield and benefit can be about the same as planting single-season rice. The key is to see how the ratoon season yield is. If the yield of ratoon rice is 200 kg, farmers will make a small profit from planting it, but there is still a gap with the requirements of national food security. Only when the ratoon season yield reaches 250 kg can a win-win situation for farmers and the country be achieved.
4. Several recommendations for further improving ratoon rice planting
4.1. Doing a good job in high-yield cultivation of main season rice is the foundation for achieving high yield in the ratoon season
4.1.1. Reasonably arrange the sowing period and sow at the proper time. To ensure that the first crop of rice matures and is harvested before August 20, to ensure normal growth and development of the ratoon season rice, and to ensure safe full heading before September 15, avoiding the "cold dew wind," and mature harvest by the end of October. We believe that the suitable sowing period should be arranged from the end of March to before April 10 (before sowing, do a good job in sunning seeds, soaking seeds, seed disinfection, and germination) to be relatively safe, and direct seeding should also be arranged before April 15, the earlier the better.
4.1.2. Cultivate strong seedlings. No matter what seedling-raising method is adopted, cultivating strong seedlings is the common goal. From the situation in Wangjiang County, using soft disk seedling raising and dry seedling raising has obvious effects on cultivating strong seedlings and promoting early development after transplanting. For dry-raised throwing seedlings, it is recommended to choose the throwing seedling type "Hanyu Baomu" (each 350 g bag of "Hanyu Baomu" can coat 1-1.2 kg of rice seed) and adopt the "coat and sow immediately" method for seed coating. Other management follows routine dry seedling raising operating procedures. Note that in selecting the seedbed, vegetable garden land or dry land with relatively sticky soil texture and fertile soil should be chosen. For longer seedling ages, the seedbed should be additionally applied with decomposed farmyard manure or soil miscellaneous fertilizer to prevent later seedling fertilizer deficiency and yellowing. The mechanized transplanting seedling technique adopts soft disk dry seedling raising. Leave sufficient seedling field according to a seedling field to main field ratio of 1:8-10. For sowing, prepare according to 2 kg of seed per mu, 75 g per seedling tray, and 22 seedling trays, and calculate the sowing period based on a seedling age of 18-20 days. Before fine sowing, prepare the seedling bed well; the seedling trays and the ground should be laid flat and firm, there should be no gaps between seedling trays, and the surroundings should be filled firmly with soil. It is recommended to dress seeds with Kangduole to improve stress resistance at the seedling stage. Seedling stage management should adopt corresponding measures to increase temperature and preserve moisture to ensure safe and complete emergence. When transplanting, the seedling requirements are: seedling height 809-200 mm, seedlings upright, stems thick and hard, roots tangled like a carpet, uniform seedling density, seedlings forming blocks that do not scatter, and roots not tangled when separating seedlings. Also do a good job in pest and disease control.
4.1.3. Reasonable close planting to ensure the number of basic seedlings. The effective panicle number of ratoon rice is closely related to the number of rice stubble of the first crop of super rice, basically showing a positive proportional relationship. Ratoon rice uses the effective panicle rice stubble of super rice with a shorter growth period as the mother body, and the high-yield structure should be built on the basis of sufficient effective panicles. We recommend a mechanical transplanting row spacing of 13.5 x 30 cm, with 60,000-65,000 basic seedlings per mu for medium-fertility fields, and 50,000-60,000 basic seedlings per mu for high-fertility fields, striving for 190,000-220,000 effective panicles per mu in the first crop of super rice. For households using throwing seedlings, we require ensuring that all seedlings from 2 kg of seed per mu are thrown and transplanted into the field. Super rice has relatively strong ratooning ability, and each mother stem can generally cultivate about 1.2 effective ratoon seedlings, which can promote the effective panicle number of ratoon seedlings to reach about 200,000 per mu, thereby ensuring high and stable yield of ratoon rice.
4.1.4. Scientific water use. Because ratoon seedlings have little root development in the early growth stage and their independent root system is not well developed enough, the nutrients needed for growth and development are mainly absorbed from old roots and supplied by the mother stem, so it is crucial that the first crop of super rice has a well-developed root system and strong vitality. For this reason, water management for the first crop of super rice should use shallow water for throwing and transplanting seedlings to promote tillering; when tillering is sufficient, expose and sun the field in time; return to shallow water at the early stage of young panicle differentiation; after applying panicle fertilizer, let the water naturally dry down and keep the field moist, with moderate light exposure to increase soil oxygen, promote rooting, and enhance rice root vitality; afterward, irrigate alternately wet and dry, and cut off water 7 days before harvest, so that at harvest the soil is moist but does not sink underfoot. In short, achieve regulating air with water and promoting roots with air, so as to achieve hard stems, strong roots, live buds, and green plants with waxy stems at maturity.
4.1.5. Scientific fertilization. Super rice plants have strong growth vigor, high fertilizer demand, and tolerance to fertilizer. Balanced fertilization should be used, and the nitrogen:phosphorus:potassium ratio should preferably be 1:0.5:1. For medium-fertility fields, with a target yield of 600-650 kg per mu, generally apply 12-13 kg of pure nitrogen, 5-6 kg of phosphate fertilizer, and 10-12 kg of potash fertilizer per mu. For high-fertility fields, with a target yield of 650-700 kg per mu, generally apply 12-15 kg of pure nitrogen, 4-5 kg of phosphate fertilizer, and 12-15 kg of potash fertilizer per mu. In addition, apply 1 kg of Maisute per mu as base fertilizer. Fertilizer application distribution: nitrogen fertilizer as base fertilizer and tillering fertilizer each accounting for 40%, and panicle fertilizer accounting for 20%; phosphate fertilizer all as base fertilizer; potash fertilizer as base fertilizer and tillering fertilizer each accounting for 30%, and panicle fertilizer accounting for 40%. In addition, special attention should be paid to applying bud-promoting fertilizer. Ratoon rice uses the dormant buds surviving on the rice stubble after harvesting short-growth-period super rice, and under appropriate water, temperature, light, and nutrient conditions, they are cultivated to germinate ratoon tillers and then head and mature. Bud-promoting fertilizer can not only prolong the functional period of the top three leaves of early rice and improve seed setting rate and 1,000-grain weight, but more importantly can promote the germination of latent axillary buds of early and middle rice. For this reason, it is essential to apply bud-promoting fertilizer well, that is, 15 days after full heading of early rice (10 days before harvest), applying 7-15 kg of urea per mu to promote the growth of dormant buds.
4.1.6. Do a good job in pest and disease control. Ratoon rice uses axillary buds on rice stubble nodes to grow and develop into panicles. It is necessary to protect the mother stems and leaf sheaths from damage by pests and diseases, and to have green branches and waxy stems at maturity. Therefore, throughout the cultivation process of early and middle rice, pest and disease control work should be strengthened according to the pest and disease situation of the local agricultural department. What must be particularly emphasized here is doing a good job in controlling rice sheath blight. At the tillering to booting stage and heading stage of rice, when the clump incidence rate is 15-20%, apply chemicals for control respectively to ensure that rice ratoon buds are not damaged by sheath blight, so as not to affect the ratoon season yield.
4.2. Effectively grasp several key points in ratoon rice cultivation technology:
4.2.1. Harvest at the proper time. The suitable time for harvesting main season rice is when striving for high yield and maintaining its ratooning vitality are coordinated; generally it should be arranged when early rice is at the 85% to 90% maturity stage. This can both maximize early rice yield and enable rice stubble to sprout quickly and have strong ratooning ability, laying a good foundation for high yield of ratoon rice. When harvesting, do not step on or damage the rice stubble at an angle; try to keep it upright.
4.2.2. Leave good rice stubble. The height of the retained rice stubble directly affects the sprouting speed, growth period, and yield of ratoon rice. Within a certain range, shorter retained rice stubble sprouts and tillers more slowly, has a longer growth period, and higher yield, while taller retained rice stubble sprouts and tillers faster, has a relatively shorter growth period, and lower yield. Therefore, the relatively ideal retained rice stubble height is about 30 cm. At harvest, it should be determined according to actual conditions. If the maturity period is earlier, harvest can wait until the main season rice is completely yellow-ripe; if the maturity period is later and it is not completely yellow-ripe, harvest can be appropriately advanced. Stubble retention can also be based on early or late timing. If early harvesting of the main season does not affect grain filling and maturing of ratoon rice, it can be retained slightly shorter, generally 25-30 cm; if the main season rice is harvested slightly later, the stubble can be appropriately retained longer, generally 30-35 cm.
4.2.3. Scientific and reasonable water use. After early and middle rice is harvested and stubble is retained, the field should be kept moist and not subjected to drought, but it also should not be flooded for a long time, so as to avoid old roots rotting and losing vitality. If high temperature and drought occur, irrigate shallow water in time to prevent rice stubble from losing water and shrinking, reducing the vitality of latent axillary buds, and affecting tillering and seedling development. After ratoon rice has enough seedlings, maintain shallow water, intermittently expose lightly, and keep moist for a long time; return to shallow water at heading and flowering and grain filling stages, and during the yellow-ripe period keep moist and let it naturally dry down to maturity.
4.2.4. Topdressing at the proper time. When early and middle rice is harvested, the ratoon buds on the rice stubble have already begun to turn green, young panicle differentiation and development are underway, and vegetative growth and reproductive growth proceed simultaneously. Therefore, after early and middle rice is harvested and stubble is retained, topdressing should be done in time to promote low-position tillering and seedling development, strong seedlings, increase the panicle formation rate, increase the number of effective panicles, and increase ratoon rice yield. Within 3 days after harvesting early and middle rice, apply 10-15 kg of urea per mu; when ratoon seedlings have grown for 15-18 days, apply 5 kg of urea and 7.5 kg of potassium chloride per mu. The time from initial heading to full heading of ratoon rice is longer than that of normal late rice, requiring about 20 days. When heading reaches 20%, spray once with 40 ml of Huaduole plus 120-150 g of potassium dihydrogen phosphate mixed with 50 kg of water per mu to promote increased seed setting rate and 1,000-grain weight and increase yield.
4.2.5. Control pests, diseases, and rodents. Ratoon rice often grows earlier and develops faster and heads and matures earlier than normal late rice, so its pests and diseases tend to be slightly more serious than those of normal late rice. Management of "transition fields" should be strengthened, especially pest, disease, and rodent control, with key attention to controlling rice thrips, stem borers, rice planthoppers, rice blast, and damage by rodents and birds.
5. Several reflections on the demonstration and promotion of ratoon rice
5.1. Zhunliangyou 608 is a very suitable high-yield ratoon rice variety. Zhunliangyou 608 is a large-panicle rice variety with greatly improved unit yield, excellent quality, and relatively strong resistance, bred by combining ideal plant type shaping with heterosis utilization. Zhunliangyou 608 has a growth period of about 130-135 days as early rice in our county, with strong tillering rate and ratooning ability, and a ratoon season of about 65 days. It has been successfully planted as ratoon rice in surrounding provinces such as Hunan, Zhejiang, and Hubei, and has been successfully planted in Wangjiang and many places in our province since 2013. The two demonstration plots visited during this observation and exchange meeting and the many practitioners who came to participate in the exchange fully prove the excellent ratooning and high-yield characteristics of the variety Zhunliangyou 608.
5.2. The fully mechanized ratoon rice "one planting, two harvests" plus green manure model with Zhunliangyou 608 is a useful supplement to the large-scale grower planting model. At present, large-scale growers, due to the transfer of rural labor, generally face difficulty in hiring workers, generally high labor costs, a single planting model, and low economic benefits. In particular, the one-rice-one-wheat model is the same as the planting model of the vast number of farming households. When workers and machinery are most needed, they cannot be hired, and many large-scale growers have to delay seedling age to more than 50 days before finishing transplanting, with yields generally reaching only about 500 kg. Because the rice growth period is delayed, it also affects the sowing and yield of summer wheat. The fully mechanized ratoon rice "one planting, two harvests" plus green manure model with Zhunliangyou 608 not only staggers with the planting model of the vast number of farming households and solves the labor shortage problem of the existing model for large-scale growers, but also does not require sowing, seedling raising, or transplanting, and does not require plowing, harrowing, or leveling fields. It saves seed, labor, fertilizer, water, and pesticide, requires less investment, and has a short growth period, requiring only more than 60 days to harvest. Adding green manure planting not only increases economic benefits but also increases ecological benefits. According to my own comparison last year, the benefit per mu of the two models differed by more than 550 yuan. This new model is worth trying by large-scale growers and worth government support.