What are the causes of yellow rice seedlings?
1, poor seed quality, growth in the field, showing uneven growth, larger area, there are individual leaves yellow or red when the emergence of seedlings, the growth is relatively slow. Near harvest, no stick or less knot stick, stick, stick and sizes etc..
2, the extensive production and management of planting too deep: sowing too shallow to emergence, too deep will appear weak seedling, seedling yellows, sowing depth should be controlled at 3 ~ 5 cm; seeds at the same time, a certain amount of fertilizer fertilizer can promote seedling growth. The thinning and final singling in corn after emergence, should be 3 ~ 4 leaves in maize were thinning, 6 ~ 7 leaves when seeding, seedlings to avoid crowded, competing for water, fertilizer, glory, the formation of weak seedling, seedling disease, Huang Miao; according to the number of reserved seedlings of different varieties and flexibility Dingmiao, according to the density of cultivars required. Inadequate watering: insufficient water before or after sowing of corn, the seeds can not get enough moisture, affecting the normal germination and emergence, and the long time of excavation, resulting in weak seedlings, yellow seedlings and so on.
3. There are many kinds of symptoms in the field of deficiency of vegetable, of which there are three kinds of deficiency, which can lead to yellow leaf of maize. The lack of nitrogen: nitrogen deficiency of maize seedling growth is slow, short and thin, leaf color yellow, tasseling late growth stage; nitrogen deficiency, the old leaves from the tip along the midrib to the base of the leaf yellow, yellow part shaped "V", the leaf margin remained green and slightly curled, finally was anxious and death. The potassium: corn potassium, root stunting, slow growth, leaf color is light green and yellow green stripes, severe leaf margin and tip are purple, then a dry burning, the middle part of the leaf blade can keep green, has gradually become wrinkled, the plant showed thin weak, susceptible to disease easy to fold down. The zinc deficiency: corn zinc deficiency will appear white flower seedlings, which is mainly characterized in maize 3 ~ 5 leaf stage, white seedlings began to emerge, new leaves pale yellow to white, especially the leaf base 2/3 is more obvious, serious aging, seedling leaves appear small white spots, and expanded rapidly. The formation of local area or white plaque necrosis, leaf necrosis, leaf like translucent, white silk or plastic film, the wind easily broken.
4, environmental and climatic factors of drought: we know that the summer thunderstorms uneven, causing some differences and other fields have drought plots, combined with topography, formed the microclimate under the effect of corn caused by drought, leaf water loss and leaf senescence, stomatal closure, old yellow, reduced photosynthesis, organic nutrient manufacturing plant and a decrease in accumulation, slow growth, small yellow, etc.. The flood: corn is a water and flood tolerant crops in high temperature and rainy conditions, the root growth stage often due to hypoxia and asphyxia caused necrosis, rapid decline, immature first withered plants.
5, the pest disease: long-term cold and rainy weather, seedlings of 2 ~ 3 leaf Qiyi occurrence of seedling blight. Cause yellow leaves wither, withered leaf edge, gradually from bottom to top dry yellow hair, less root Brown dysplasia, causing yellowing and weak seedling. The main pests of maize seedling pest thrips, Swedish meromyza saltatrix, wireworms, cutworms, Geng Kui mealybug etc.. Thrips, Swedish meromyza saltatrix drill into the harm of maize seedling leaves, which were twisted and rolled together, not forming a "shelter", were broken yellow, yellow stripe. The underground pests (Jin Zhenchong, tiger, Geng Kui mealybug) on maize seedlings near surface of stem borers in feeding stems, causing severe wilting of seedlings yellow sprout deficiency.
The 6 part, the herbicides farmers arbitrarily increase the dosage of herbicide and other pesticides mixture; blind medication; high concentration; sprayer interoperability; use of counterfeit herbicides; residual stubble herbicide; above the improper use of the herbicide, will cause leaf yellowing seedlings after shrinkage, dwarf plants, stop the growth of some leaf blight phytotoxicity spot phenomenon. Which is mainly due to the season of wheat years (such as the use of herbicides of Metsulfuron methyl and tribenuron methyl, etc.), soil water shortages caused by drought weather, advocate years ago the use of herbicides, if the year after application to avoid the use of herbicides of Metsulfuron methyl and tribenuron methyl. The main reason is due to the 2012 corn seedling yellow stubble wheat field drought, crop herbicide degradation slow, affect maize seedling by crop herbicide is larger, the root is weak, the leaves fold, yellow, the formation of "old yellow seedling".
7, the physiological characteristics of maize yellow seedling is mainly caused by the variety itself, the main symptom is the lower leaf stem tip, yellow leaves, and root growth is normal, is generally 5 leaves per plant of maize after normal, the corn yellow leaves with brassinolide can quickly restore.
How to prevent and cure yellow rice seedling
1, conditional organic fertilizer should be added.
2, try to use large harvester for harvesting the straw.
3, the machine can not block, to high stubble, stubble when crushed.
4, the spring soil preparation should not be too clean, as much as possible leaving some straw and corn leaves, in order to increase soil organic matter content.
5, sow not too deep.
6, low-lying cold land should pay attention to trenching drainage, in order to improve soil temperature.
7, pay attention to the prevention and treatment method of toxic fertilizer application.
8, the use of jade after threshing rice chaff and hair shop in a ditch, and then use the rotary tillage.
9, in case of yellow seedlings, timely spraying foliar fertilizer.
