How to Select Sesame Seeds? A Detailed Guide to Raising Seedlings

Flax is what we usually call sesame in everyday life. Many people use sesame at home to make all kinds of delicious snacks. Sesame can not only be made into snacks, but can also be pressed for oil, and sesame oil is also very popular on the market. So how do you select sesame seeds? What are the methods for raising sesame seedlings?

1. How to Select Sesame Seeds?

1. Look at the appearance

The shape of sesame seeds includes flat oval and long oval. One end is round and blunt, and the other end is slightly pointed. The pointed end retains the trace left by the shed seed stalk, namely the hilum; in some varieties, such as Laobuzhangzui, this end is curved. From the hilum along one side of the seed to the other end there is a longitudinal line called the raphe, which is the tiny vascular bundle leading into the interior of the seed to transport water and nutrients. Sesame seeds are relatively small, with a 1000-grain weight generally around 2.6-3.5 grams, belonging to the small-seeded crops among field crops.

2. Look at the seed coat

The colors of the sesame seed coat include white, yellow, brown, black, and so on, and each color also varies in depth and shade. This is caused by differences in the types and amounts of pigments contained in the epidermal cells. Generally, seeds with lighter color have a higher oil content than those with darker color.

2. Methods for Raising Sesame Seedlings

1. Choose the seedbed

Before raising seedlings, the seedbed must first be chosen. A plot that is sheltered from the wind and faces the sun, has flat terrain, fertile and loose soil, good water and fertilizer retention, and convenient water sources is better; moreover, sesame should not have been planted in the previous 2-3 years, and the previous crop of the seedbed is best rapeseed or wheat, not legume or solanaceous crop stubble, so as to reduce disease. Leaving enough seedbed area is an important condition for thin sowing and cultivating strong seedlings. If the seedbed area is small and the sowing rate is too large, seedlings will crowd each other, forming leggy or weak seedlings and causing poor root development. The seedbed area should be determined according to the planned field area and planting density. Generally, the ratio of seedbed to field is 1:15 for summer sesame and 1:10 for autumn sesame.

2. Land preparation and fertilization

Sesame seeds are small, and their ability to emerge through the soil after germination is weak, so seedbed preparation must achieve level, fine, and firm conditions, that is, before sowing, plow and sun-bleach the seedbed, break up clods, open ditches and make beds, with bed width 1-2 m, furrow width 0.4 m, furrow depth 0.2 m, a level bed surface, finely broken soil, and a soil layer that is loose on top and firm below, convenient for operation and irrigation and drainage. Apply basal fertilizer shallowly in combination with land preparation; generally, apply 1000 kg of decomposed pig manure or 500 kg of human manure, 20-25 kg of superphosphate, and 5 kg of potassium chloride per mu of seedbed, spread evenly on the bed surface, mix into the surface soil during land preparation so that soil and fertilizer are fully mixed, and then level the seedbed and make the beds.

3. Sterilization treatment

Before sowing, choose a sunny day and spread the seeds in the sunlight to sun them for 1-2 days, which can improve germination vigor. Use the winnowing method to remove moldy seeds, blighted seeds, and leaf and branch impurities, leaving top-grade seeds that are large, plump, and free of pests, diseases, and impurities. It is best to sow seeds coated with a seed coating agent. Before sowing, use 0.75 kg of 40% carbendazim wettable powder per mu, mix with an appropriate amount of dry soil, spread evenly on the surface layer of the seedbed and lightly harrow to sterilize the soil. Soak the seeds in 5°C warm water for about 20 minutes, which can kill the pathogens carried on the seeds; dry the seeds and then sow.

4. Fine sowing

Sesame should be sown early at the appropriate time to give full play to the yield-increasing advantage brought by seedling raising and transplanting. The specific time should be determined according to the harvest period of the previous crop; generally, sowing about 20 days before the previous crop is harvested is suitable. Seedbed sowing is generally broadcast sowing, sown evenly at suitable moisture. Sowing must be carefully calculated, neither wasteful nor leaving gaps in seedlings. Generally, sow 0.8-1 kg per mu of seedbed, with a fixed quantity per bed and even sowing, ensuring no missed sowing, no clustered seeds, and no deeply buried seeds. After sowing, press the bed surface firm so that the seeds are in close contact with the soil.

After sowing, water the bed surface with dilute liquid manure, or spray with 0.2% borax solution + 0.4% potassium dihydrogen phosphate solution until mixed; if dry weather occurs, after sowing a small amount of chopped rice straw can be spread over the bed surface and watered to retain moisture, striving for early and uniform emergence. Because sesame seeds are tiny, it is best to sow with fine soil. Sesame seeds coated with a seed coating agent are easier to sow evenly. If the temperature is relatively low, after the bed surface is dried and the surface moisture is gone, cover with film and build a frame. When 10% of the seeds have emerged, if it is sunny and the temperature is high, uncover the film in the morning and cover it again in the afternoon to prevent damage to the seedlings from high temperatures during the day and low temperatures at night. The sowing period is set according to transplanting at a seedling age of 20-25 days.

5. Seedbed management

(1) Thinning and final thinning: early thinning and sparse final thinning are required. When the first pair of true leaves appears on sesame, carry out the first thinning, with a seedling spacing of about 2 cm, "remove weak seedlings and keep strong ones; remove small seedlings and keep large ones; remove dense seedlings and keep evenly spaced ones; remove mixed seedlings and keep pure ones; remove diseased seedlings and keep healthy ones," so that seedlings do not crowd each other; at the second and third pairs of true leaves, carry out the second thinning, with a seedling spacing of about 4 cm, so that leaves do not overlap; at the fourth pair of true leaves, carry out final thinning, with a seedling spacing of about 6 cm. Keep 270 seedlings per square meter.

(2) Topdressing and watering: seedbed fertilizer and water management should adopt the method of promoting first and controlling later. Before the 3rd pair of true leaves, mainly promote; after the 3rd pair of true leaves, control fertilizer and water. If dry after sowing, water in time to resist drought, and water well for germination and emergence, so that the soil surface does not turn white. After full emergence, reduce the number of waterings to promote downward rooting. Fertilization during the seedling stage follows the principle of "small amounts, many times," fertilizing once after each thinning, each time using 3-4 kg of urea per mu, mixed with 1000 L of water, or splashing 250-500 kg of dilute human and animal urine. Apply a starting fertilizer within 1 week before transplanting so that the seedlings absorb more nitrogen in a short time; 8-10 kg of urea per mu can be applied with water.

(3) Chemical regulation: raising seedlings in plastic greenhouses results in fast emergence and rapid leaf growth. If the seedbed density is high, abnormal seedling types such as excessive-growth seedlings and leggy seedlings are easily formed. Applying growth retardants such as paclobutrazol and uniconazole during the seedling stage has a significant effect on regulating seedling growth and improving seedling quality. In production, at the 1-2 pairs of true leaves stage of sesame seedlings, evenly spray the seedlings with 150 mg/kg paclobutrazol or 40 mg/kg uniconazole solution to promote short, sturdy seedlings with more green leaves and darker leaf color. If dry weather occurs, the concentration of the paclobutrazol solution can be reduced to 100 mg/kg; in rainy weather, its concentration should be increased to 150-200 mg/kg, and an additional spray may be applied as appropriate. It is best to spray the paclobutrazol solution in the afternoon, and to spray finely and evenly, avoiding repeated or missed spraying.

(4) Pest, disease, and weed control: during the sesame seedling stage, pests and diseases such as aphids, cabbage caterpillars, yellow curved flea beetles, and damping-off are prone to occur and should be controlled in time. Remove weeds in combination with thinning. When the rate of plants with aphids in the seedbed reaches 10%, and each plant has 1-2 aphids, spray with 1000-fold 40% dimethoate emulsion; for cabbage caterpillars before the 3rd instar, spray with 800-1000-fold 2% abamectin emulsifiable concentrate per mu; to control seedling damping-off, carbendazim can be used for seedbed soil disinfection and medicated soil covering of seeds, and at the early stage of disease, spray with 500-600-fold 25% carbendazim wettable powder once every 3-5 days, continuously 2-3 times. To prevent disease, generally after the seedlings have fully emerged, spray the entire bed 1-2 times with 800-1000-fold 70% thiophanate-methyl wettable powder, or 800-fold 40% carbendazim suspension concentrate.

In summary, the above is all the content on sesame seed selection and seedling raising. When choosing to plant sesame, everyone must select a variety suitable for themselves according to the local climate and environment.

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