Soybean Good Seed Propagation Methods and Key Technical Points

Soybean is a self-pollinating crop. Due to mechanical mixing, adverse climatic and cultivation conditions, and natural cross-pollination, the varietal characteristics often deteriorate. Therefore, self-pollinated seeds cannot be used long-term, and seeds should be replaced every three years. Thus, it is necessary to persist in purification and rejuvenation and carry out good propagation work to maintain the varietal characteristics of good varieties.

1. Purification and rejuvenation methods for soybean varieties

(1) Line selection The commonly used method for soybean purification and rejuvenation consists of three steps: individual plant selection, line identification, and mixed high-ratio propagation. Three plots are established: an individual plant selection nursery, a line comparison nursery, and a mixed propagation nursery.

Individual plant selection nursery: Select typical excellent individual plants for seed testing and thresh individual plants separately. Eliminate individual plants whose traits such as seed color, seed shape, and hilum color are inconsistent with the original variety.

Line identification nursery: Plant each individual plant as 1 row (a line). Eliminate lines inconsistent with the original variety. For the planting design, a control row (original variety) can be planted every 10-20 rows. Selected lines are used as propagation seed for the next year.

Mixed propagation nursery: Sow the seeds obtained from the above line identification and mixed harvest at equal spacing and sparse density for high-ratio propagation.

The seeds produced through the above 3 nurseries are called purified and rejuvenated super stock seed.

(2) Mass selection When soybeans mature, select a certain number of robust and excellent individual plants with the typical characteristics of the variety, then conduct strict indoor re-selection, then thresh them together and store them separately as seed for the next year's propagation field. The propagation field should adopt advanced cultivation and management measures, and strictly remove off-types and inferior plants.

(3) Single-plant transmission Select an excellent individual plant with the typical traits of the original variety, and carefully cultivate and propagate its progeny. In this method, seeds from a single line are harvested and multiplied; the time required is slightly longer than that of the line selection method.

2. Establish a seed field

Because the amount of soybean super stock seed obtained through purification and rejuvenation is very small, a seed field needs to be established to propagate production seed in large quantities.

The area of the seed field is determined by the amount of sowing seed and the yield per mu of the seed field. Generally, the area of the seed field can be 4%-5% of the area of the production field or the next higher-level seed field. For plot selection of the seed field, choose a plot that is flat, well-drained, uniform in soil fertility, and not continuous cropping or adjacent cropping. Apply more farmyard manure, and apply chemical fertilizer according to the nitrogen and phosphorus ratio. Strengthen field management, thin seedlings in time, cultivate and weed at the proper time, and earth up so that the soil is loose and free of weeds. During the flowering and pod-filling period, apply topdressing 1-2 times, irrigate in time during drought, and control pests and diseases in time. Throughout the entire growth period, according to morphological traits, strictly remove off-types and inferior plants at the seedling stage, flowering stage, and maturity stage. After maturity, harvest at the proper time, and strictly manage the links prone to mechanical mixing, such as harvesting and threshing.