What are the causes of yellowing in rapeseed seedlings and what are the remedies?

Rapeseed has long been an important oilseed crop and cash crop in China, with a long history of cultivation, and by September it is the season for planting rapeseed in southern China and the Yangtze River Basin. However, many rapeseed growers often encounter the phenomenon of rapeseed seedlings turning yellow, so what causes this? And how should it be solved? Let's find out together.

I. Causes of yellowing in rapeseed seedlings

Yellowing in rapeseed seedlings is generally caused by three situations. First, the rapeseed was not plowed before sowing; rapeseed sowing generally requires two rounds of plowing before sowing. The first round involves deep plowing of large clods of soil, after which the soil is sun-dried for a week, and the second round is carried out at sowing time, when the soil should be broken up fine, and sufficient base fertilizer should be applied before plowing. The second situation is that the previous crop was a broad bean field, where the residual pathogenic bacteria are greater, because broad beans suffer from relatively severe diseases, and after harvest the pathogens remain in the soil, causing harm to rapeseed seedlings. The third is that no pest and disease control was carried out, leading to worsening disease and causing the seedlings to turn yellow.

II. Remedial measures

1. During the seedling stage, do a good job of clearing ditches and draining water to avoid waterlogging, and at the same time be prepared for timely sowing. Rapeseed is relatively sensitive to sowing time, and rapeseed needs certain temperature conditions for germination, seedling emergence, rooting and leaf growth. The optimum temperature for germination is 16-22 degrees, and leaf emergence requires above 10-15 degrees to proceed smoothly. For the seedbed, it is recommended to choose fertile soil and a plot close to a water source.

2. Spray foliar fertilizer on the rapeseed. It is recommended to use 0.1-0.3% potassium dihydrogen phosphate or phosphorus-potassium essence and similar agents for foliar spraying to promote the growth and development of the rapeseed seedling root system, so that the yellowing recovers as soon as possible. In terms of topdressing, nutrients should also be supplied in a timely manner according to the growth of the rapeseed, and appropriately increasing the application of phosphorus and potassium fertilizer can greatly reduce the yellowing phenomenon.

3. Proper pruning and pinching off the tips encourages the rapeseed to produce more branches, form a good population structure, and enhance disease resistance, which can effectively prevent the yellowing phenomenon in rapeseed and is also one of the ways to obtain a high yield.

4. Timely prevention and control of pests and diseases is also one of the main measures to prevent yellowing in rapeseed seedlings. During the growth cycle of rapeseed, the main pest and disease threats are cabbage caterpillars, flea beetles, aphids, etc. It is recommended to use 25% Decis 3000-fold solution or 40% dimethoate 1000-fold solution for spray control.

The above is an introduction to the causes of yellowing in rapeseed seedlings and the remedial measures. We hope it can help you. To learn more related knowledge, please stay tuned to us.