At this stage, most rapeseeds have entered the stage of silique ripening from the end of flowering to the ripening of silique seeds. The vegetative growth at this stage has basically stopped, and the photosynthetic function of the leaves has gradually been completely replaced by siliques. After the rape blossoms, the ovary in the flower expands to form young siliques, which gradually form large siliques. The leaves on the plant have fallen off in a large amount, and the siliques gradually transform into the main organ of photosynthesis. At the same time, part of the nutrients absorbed by the root system and the nutrients stored in the stems and branches are also continuously transported to the seeds. Continue to accumulate until the seeds are fully mature. This period is an important period to determine the number of effective siliques, grain weight and oil content.

01 The characteristics of silique development

The length of the development period of rape siliques and seeds has a great relationship with varieties and climatic conditions. According to observations, the silique development period of early and mid-maturing varieties of cabbage type is 22 to 35 days, generally about 27 days; the mid- and late-maturing varieties of cabbage type are 23 to 31 days, generally about 25 days. In addition, during the development of siliques, if the weather is clear, sunshine is sufficient, the temperature is above 20℃, and the soil humidity is above 70%, as long as the plants are not decay, the photosynthesis of the siliques is strong, and the siliques will develop faster and more developed. Good, the seed oil content is also high, suitable for the development and fruit of the mature period. However, if the temperature is too high and the air is dry, the seeds will mature quickly, but the seeds will have low plumpness and low oil content. In production, this is usually called high-temperature forced ripening. On the contrary, if the weather is continuous and rainy, and the application of more nitrogen fertilizers, the rape will become greedy and mature, resulting in insufficient grains and a decline in yield and oil content.

02 Sequence of development of rape siliques

There is a certain order in the development of rape siliques. Generally, the flower siliques that open first develop first. The sequence of the development of each silique is: first elongate in the longitudinal direction, then expand to a certain extent, and then expand in the transverse direction. While the rape silique develops, the seeds also develop. The general process is: the proliferation stage of the fertilized egg cell, one stage of embryo development, and the other stage of embryo fullness. By 33 days after flowering, the cotyledons and radicles are closely connected, and the seeds are almost entirely occupied by embryos.

03 Accumulation process of rapeseed and oil As the seed is formed, its dry weight and oil will gradually accumulate. Generally, the dry weight and oil content of seeds reach their maximum values 30 to 45 days after flowering. According to research, the process of oil accumulation is accomplished through three aspects of material transformation, namely, 40% of nutrients stored in plant stems, leaves and other organs, photosynthetic products from green stem bark account for about 20%, and silique peel The photosynthetic products account for about 40%. The nutrients in these three aspects are all formed by sucrose or starch and converted into soluble monosaccharides, and then formed into oil through the action of lipase. As the seeds are full and full, the oil accumulation is basically finalized. The color of the siliques changes from green to yellow-green, and finally becomes yellow. At this time, the seeds are mature.

04 Rapeseed silique period management

In the field management in the later stage, it is necessary to do a good job in field cleaning and drainage, not only to prevent the premature senescence of rape plants due to defertilization, but also to prevent excessive application of nitrogen fertilizer, so as to effectively increase the yield and oil content of rape seeds.