Timing for controlling excessive growth in sesame: does the 4-6 leaf stage work?

AbstractThe time to control excessive growth in sesame is during the full fruiting stage, during which the terminal bud at the top can be removed. If the planting area is relatively large, mepiquat chloride or chlormequat can be sprayed during the full fruiting stage to control excessive growth. During the seedling stage of sesame, diluted decomposed human excrement or urea can be applied as a top dressing; at the bud stage, nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer can be applied as a top dressing; during the flowering stage, decomposed manure, cake fertilizer, barnyard manure, etc. can be applied as a top dressing.

I. Timing for controlling excessive growth in sesame

1. The suitable time to control excessive growth in sesame is during the full fruiting stage, during which the terminal bud at the top can be removed. If the planting area is relatively large, growth regulators can be sprayed during the full fruiting stage to control excessive growth, generally mepiquat chloride or chlormequat, applied as a foliar spray.

2. Because the sesame stem is upright, it casts little shade, so sesame is often used in mixed cropping with short-statured crops, such as mixed cropping or intercropping with sweet potato, peanut, soybean and other crops.

3. Usually, in sweet potato fields, one row of sesame is intercropped every 2-4 rows of peanut, or one row of sesame is intercropped in the furrow every 1-2 rows. Sesame is relatively drought-tolerant, while legumes are relatively moisture-tolerant, so mixing sesame with legumes helps prevent both drought and waterlogging.

4. Sesame is mainly distributed in the provinces along the middle and lower reaches of the Yellow River and the Yangtze River, as well as in Anhui, Hubei, Jiangxi, Henan, Hebei and other provinces, among which Henan's output accounts for about 30% of the national total. According to statistics, the national sesame planting area is about 790,000 hectares, with an output of about more than 580,000 tons.

II. When to fertilize sesame

1. Seedling stage

(1) Generally, applying too much nitrogen fertilizer at planting time can easily cause excessive growth of seedlings, thus forming leggy seedlings, so at the sesame seedling stage only part of the nitrogen fertilizer is generally used as a base fertilizer.

(2) Growers have a saying of “top dressing according to the seedlings”. Generally, when the seedling vigor is relatively poor, or when there is a relatively large difference in seedling size, a small amount of appropriate seedling-promoting fertilizer can first be applied, with diluted decomposed human excrement or urea giving better results, because at this stage the sesame root system is relatively shallow, so fertilization should be applied as shallowly as possible.

2. Bud stage

The bud stage is the period of flower bud differentiation. Generally, the vegetative growth and reproductive growth of sesame proceed simultaneously, and top dressing at this period gives relatively good results. During this period, top dressing should be mainly nitrogen fertilizer, supplemented by phosphorus fertilizer and potassium fertilizer, and an appropriate amount of boron fertilizer can also be applied in boron-deficient areas.

3. Flowering stage

(1) Sesame grows relatively rapidly once it enters the flowering stage. The nutrients absorbed at this stage account for 70%-80% of the entire growth period. In order to meet the needs of plant growth and development, promote vigorous growth of sesame, accumulate more photosynthetic products, and at the same time increase the number of flowers and capsules, maintain steady growth in the later period without premature senescence, and promote full and plump seeds, flower fertilizer must be applied heavily.

(2) At this stage, the lateral roots of sesame have begun to form in large numbers, so the absorption capacity of the root system is enhanced, and at the same time the growth rate of the plant will also accelerate, so the demand for nutrients also increases significantly. Generally, when fertilizing, chemical fertilizers are more convenient, and during this period decomposed manure, cake fertilizer, barnyard manure, etc. can also be applied.