Urea , also known as carbon amide, chemical formula is CH4N2O or CO(NH2)2 [8]

Urea (urea), also known as urea, carbon amide, chemical formula is CH4N2O or CO(NH2)2 [8], is an organic compound composed of carbon, nitrogen, oxygen, hydrogen, is a white crystal. One of the simplest organic compounds, it is the main nitrogenous end product of the metabolic breakdown of proteins in mammals and some fish.

physical properties

Urea is easily soluble in water, 105 grams can be dissolved in 100 ml of water at 20°C, and the aqueous solution is neutral. There are two types of urea products. Crystalline urea is white needle-like or prism-like crystal shape, and has strong hygroscopicity. [1] Granular urea is a translucent particle with a particle size of 1 to 2 mm, with a smooth appearance and significantly improved hygroscopicity. The critical moisture absorption point at 20°C is 80% relative humidity, but at 30°C, the critical moisture absorption point drops to 72.5%, so urea should be kept open in humid climates in midsummer. Adding hydrophobic substances such as paraffin in urea production greatly reduces its hygroscopicity.

Adjust the amount of flowers

In order to overcome the age of apples, in the case of small years, 5-6 weeks after flowering (the critical period of apple flower bud differentiation, the growth of new shoots is slow or stopped, and the nitrogen content of leaves shows a downward trend) foliar spray with 0.5% urea aqueous solution , Continuous spraying 2 times can increase the nitrogen content of leaves, speed up the growth of new shoots and inhibit the differentiation of flower buds, so that the amount of flowers in the big year is suitable.

Flower thinning and fruit thinning

The flower organ of peach tree is more sensitive to urea, but the reaction of the surface is relatively slow. Therefore, foreign urea has been used on peaches and nectarines to conduct flower thinning and fruit thinning experiments. (7.4%) to show good effect, the most suitable concentration is 8%-12%, within 1-2 weeks after spraying, the purpose of thinning flowers and fruits can be achieved. However, under different land conditions, the response of different periods and different varieties needs further experiments.

rice seed production

In the hybrid rice seed production technology, in order to increase the outcrossing rate of the parental parent, to increase the amount of hybrid rice seed production or the breeding volume of sterile lines, gitoxin is generally used to spray the female parent to reduce the degree of cervical encroachment of the female parent or to make It can be completely extracted; or spray the parent parent to adjust the growth of the two to synchronize the flowering period. Because gibberellin is more expensive, the cost of seed production is high. People use urea instead of gibberellin for experiments, and use 1.5%-2% urea at the peak booting stage and the beginning of the ear (20% heading), the breeding effect is similar to that of gibberellin, and the plant height will not increase.