Timely Early Sowing Measures and High-Yield Cultivation Techniques for Summer Sesame
The main sesame-producing areas in China mostly practice summer sowing, and for a long time yields have been low and unstable. This is certainly related to frequent disasters, but the more important reason is late sowing, a short growth period for sesame, and inadequate and irrational use of climatic resources. To solve this problem, in recent years we have carried out careful research on how to sow summer sesame earlier and on supporting cultivation techniques, and have preliminarily summarized a set of high-yield cultivation techniques.
1 Analysis of the reasons for increased yield from early sowing of sesame
1.1 Full use of climatic resources The main sesame-producing areas in China, including the Huaibei region, Jianghan Plain and Nanyang Basin in Henan, Hubei, Anhui and other provinces, are located in the mid-latitude zone of the East Asian continent and have typical monsoon climate characteristics. From late May to early September is the period with the most abundant light and heat resources in the year, and it is also the season suitable for sesame growth and development. Advancing the sowing date of summer sesame to mid-May, and at the latest around June 1, allows the climatic resources of this stage to be used to the maximum extent. This provides more effective accumulated temperature and sunshine hours over the whole growth period than sesame sown after wheat harvest following plowing. Sesame is a crop that likes warmth and light, and when climatic conditions are suitable it has the habit of continuous growth and continuous flowering. Because effective accumulated temperature and sunshine hours increase, this lays the foundation for achieving high yields of summer sesame.
1.2 Avoiding or reducing the impact of disastrous weather Sesame generally can emerge in late May and can form buds before the end of June. During the entire seedling stage the temperature is not too high, sunlight is sufficient, and the atmosphere is dry, which is conducive to early development and steady growth of sesame. After July, the flood season gradually begins. At this time, as long as drainage and waterlogging prevention are done well, high temperatures and abundant rainfall are conducive to vigorous growth, flowering and capsule formation of sesame. After mid-August the flood season has passed and the temperature drops noticeably, but at this time sesame is approaching topping and the end of flowering, and relatively dry weather is conducive to grain filling and seed setting. Therefore, early-sown sesame shows tall plants, low branching position, many capsules, large capsules, plump seeds, high 1000-grain weight, and short yellow tips.
2 Several measures for achieving early sowing of summer sesame
2.1 Interplanting sesame in wheat ridges
2.1.1 The best time for interplanting sesame in wheat ridges Around May 20 is the best time for interplanting sesame in wheat ridges. Compared with after wheat harvest, rainfall during this period is more reliable, soil moisture is good, and atmospheric evaporation is low, which is conducive to full emergence of sesame from a single sowing. Compared with sowing after plowing following wheat harvest, this measure of interplanting sesame in wheat ridges extends the effective flowering period by at least 10-15 d, thereby laying the foundation for high yields of summer sesame.
2.1.2 Selection of previous crop @#@245@#@ varieties and planting method Select improved wheat varieties with short stalks, early maturity and high yield (such as Yumai 18 and Zhengmai 9023), and adopt a planting method with wide rows of 24 cm and narrow rows of 12 cm. In wheat management, control water and fertilizer, implement chemical regulation techniques, and prevent wheat lodging. Also use chemical weed control to eliminate weeds in the wheat field, so as to facilitate field operations for interplanting sesame in wheat ridges. Wheat fields sprayed with chlorsulfuron after December are not suitable for planting sesame the following year.
2.2 Interplanting sesame between garlic rows
2.2.1 The best time for interplanting sesame in garlic fields Around May 15 is the best time for interplanting sesame in garlic ridges. During this period, 90% of garlic leaves have entered senescence, which is exactly a favorable time for field operations and sowing sesame.
2.2.2 Planting method for interplanting sesame in garlic fields Generally, the row spacing of garlic is 21-24 cm, and sesame is sown in a 2:1 pattern. If soil moisture is insufficient before sesame sowing, irrigate once with "garlic farewell water" first, which is conducive to full emergence of sesame from a single sowing.
2.3 Sowing sesame on stubble without plowing
2.3.1 Sowing in good time After wheat harvest, sow in good time according to soil moisture. Sesame sown during this period can enter the flowering stage 5-7 d earlier than sesame sown after plowing. Otherwise, sesame sown after plowing enters the high-temperature and rainy season soon after emergence, causing excessive vegetative growth, followed by low temperatures later that affect grain filling and maturity of sesame. Therefore, sesame planted after plowing following wheat harvest often develops short plants, a high branching position, sparse capsules, small capsules, shriveled seeds and long yellow tips.
2.3.2 Method for sowing sesame on wheat stubble After wheat harvest, sow in good time by seizing soil moisture. The methods are: (1) When moisture is sufficient, first sow 10-15 kg of diammonium phosphate (or monoammonium phosphate) with a drill, then broadcast the seeds along the rows. (2) If sowing technique is good, diammonium phosphate and sesame seeds can be mixed together and sown. Remember that the amount of chemical fertilizer mixed for sowing should not be excessive, otherwise it will affect sesame emergence. (3) When soil moisture is insufficient but does not affect emergence, sow sesame seeds first, and after sesame emerges and reaches the bud stage, apply the same amount of chemical fertilizer as a topdressing. All three sowing methods above require timely leveling after sowing to preserve soil moisture, which is conducive to emergence.
3 Supporting high-yield cultivation techniques for sesame
3.1 Reasonable close planting The results of density trials show that the planting density in high-yield fields should be controlled at 8000-9000 plants per mu, while for ordinary soil fertility 10000-12000 plants per mu should be retained.
3.2 Scientific fertilization Sesame fertilization should be scientific. The fertilization principle is to control nitrogen fertilizer and increase potassium fertilizer. Under ordinary medium soil fertility conditions, apply 5-6 kg of pure nitrogen, 5-6 kg of phosphorus pentoxide, and 3-5 kg of potassium oxide per mu. At sowing, 10-15 kg of diammonium phosphate can be applied as seed fertilizer, and after the bud stage 5-7.5 kg of urea can be applied as flower-bud fertilizer. Potassium-deficient soil should be appropriately supplemented with potassium fertilizer. If plants show signs of nutrient deficiency at the topping stage of sesame, broadcast 1.5 kg of urea per mu together with rain or irrigation to promote grain filling of sesame and achieve plump, heavy seeds in the upper part.
3.3 Field management
3.3.1 Seedling stage management After sesame emerges, the previous crop has already been harvested, so thinning and weeding should be carried out in good time to prevent overcrowding of seedlings and weeds. After final thinning at the 4 pairs of true leaves, carry out topdressing and earth up around the roots when soil moisture is sufficient.
3.3.2 Drought prevention and drainage In sesame fields, according to the terrain, dig moisture furrows and waist furrows well so that the three types of ditches are connected, allowing surface water to drain and subsurface water to seep away. After entering the flowering stage, this has a great influence on sesame growth. If leaves show wilting in the afternoon, irrigate in good time to prevent drought from causing growth cessation, flower drop, bud drop, early end of flowering and topping.
3.3.3 Pest and disease control During the sesame growth period, focus on integrated pest and disease control, especially in chemical control by adopting multiple and varied integrated control measures. At the seedling stage, strictly control underground pests. After final thinning, spray pesticide once every 7 days. The pesticides used are generally those with good control effects, such as carbendazim, thiophanate-methyl, virus A, chlorpyrifos and deltamethrin, applied in rotation. When spraying at the full flowering stage, combine with potassium dihydrogen phosphate, borax and anti-senescence hormones, etc., so as to reduce pest and disease losses while also meeting the fertilizer requirements of sesame in the middle and late stages and delaying senescence.
3.3.4 Topping, leaf protection and timely harvest The test results show that topping sesame increases yield by about 10% compared with no topping. For the topping time, early spring-sown crops should be topped around the end of July, while sesame sown on stubble without plowing should be topped on August 5-7 (7 days before the Start of Autumn). The topping length should be within 1 cm. Protecting leaves near the end of flowering is crucial for sesame. Removing leaves reduces yield by 23.3% compared with not removing leaves, and the earlier the leaves are removed, the greater the yield reduction. Sesame can be harvested when the lower capsules show capsule splitting or when the seeds in the middle part of the plant show the inherent seed color. After harvest, tie into small bundles and dry in the sun. Stacking in a closed pile is strictly prohibited to ensure seed color.