How to prevent and control the shrinkage of rice seedlings due to zinc deficiency

The shrinking seedlings of phosphorus deficiency generally occurred at the tillering stage after slow seedling, such as slow growth, short plant, slender and erect leaf shape, dark green leaf color, neat top of leaf cluster, significant shortening of leaf occipital distance, redness of some tillering leaf tips and even death of old leaves. The reasons are: first, the soil is lack of available phosphorus; second, the soil temperature and water temperature are low, or the soil contains hydrogen sulfide, ferrous and other reducing harmful substances, which reduce the absorptive capacity of roots; third, excessive application of nitrogen fertilizer, the relative balance of effective nutrients is lost. The control measures determine the reasonable amount of phosphorus application according to the data of effective components of phosphorus measured by "soil testing and fertilization method".

Mild zinc deficiency, brown spots on the basal leaves, moderate zinc deficiency, light green leaves, increased rust, green and white midrib, severe zinc deficiency, shortening of leaf occipital distance, inhibition of growth, smaller new leaves, dwarfing plants, hindering tillering, serious black root, delayed heading and serious yield reduction. Causes: low content of available zinc in soil, or excessive application of phosphate fertilizer and ammonia fertilizer, imbalance of ammonia-zinc ratio; in addition, large amount of organic fertilizer, coupled with long-term stagnant water, is also easy to cause zinc deficiency. Control measures: 667m2 application of zinc sulfate 1 kg 1.5 kg, or after slow seedling, shallow application of 0.1% zinc sulfate solution 0.2% zinc sulfate solution.

This kind of shrinking seedlings caused by saline-alkali injury is a complication of saline-alkali, phosphorus deficiency and zinc deficiency, which mostly occurs in the coastal rice area. the main performance is that the leaves curl vertically from top to bottom, the roots die quickly, and the leaves do not spit. The tip of the lower leaf begins to fade from the leaf base after the longitudinal roll, and develops upward until the leaf dies. The cause: the saline-alkali content of soil or irrigation water is high, or the pH value of irrigation water is high. Prevention and control measures: soaking and alkali washing should be carried out in saline-alkali soil rice areas, and the standard of saline-alkali content in irrigation water should be strictly grasped according to the saline-alkali tolerance of rice at different growth stages, so as to achieve a smooth flow of irrigation water and maintain a water level difference of more than 40 cm between the field surface and the drainage ditch, so as to reduce the pH value of the rice field.