Zinc is a nutrient that is essential for the biological and metabolic functions of plants and animals. Although zinc is considered a micronutrient in terms of its low content, its functions are very important which is essential for the survival of the organism. Agricultural scientists have been realizing the need for zinc in the agriculture of our country since the eighties. There is no point in ignoring the use of zinc in rice-based crops. Zinc deficiency hinders the growth and development of plants and reduces yields, just as zinc malnutrition causes various diseases in the human body. In particular, zinc deficiency causes loss of appetite, growth of children, abnormalities in hair and nails, imbalance in bone formation, delays in wound healing, infertility, diarrhea, anemia, nervous weakness, night blindness, mental instability and diabetes. Statistics show that one-third of the world's population suffers from zinc deficiency malnutrition. According to UNICEF, zinc deficiency kills more than four million children worldwide. At least 50 percent of the world's agricultural land is deficient in zinc, which is hampering crop production on the one hand, and increasing zinc malnutrition in the human body on the other. People in developing countries are more prone to zinc deficiency as they eat more grains.
The role of zinc in plants
Zinc in the plant helps in the formation of growth hormone auxin. By synthesizing meat, it participates in the formation of chlorophyll. Gives firmness or integrity to the cell membrane. Enzymes make its functions dynamic. Regulates pollen formation.
Symptoms of zinc deficiency
When zinc is deficient in plants, chlorosis occurs at the beginning of the midrib and the leaves lose their green color and turn white. Growth is reduced and the tree is shortened. The crop takes longer to mature. As the shape of the leaf gets smaller, gradually smaller clusters of leaves are formed which are known as rosetting. The lower leaves have brown spots. Later the leaves take on a brownish shape and gradually take on a burnt color. The middle veins of citrus plants are green but the middle part of the veins turns white. The leaves of leguminous plants, especially mugdals, turn yellowish at an early stage. Later necrosis occurs in the middle part of the vein but the vein is still green.
The cause of zinc deficiency in soils and plants
Zinc deficiency in soils and plants is due to: 1. Zinc is less available in alkaline (pH> 7.5) calcareous soils rich in high calcium and magnesium bicarbonate. 2. If there is high level of phosphorus in the soil, insoluble chemical compounds like zinc phosphate are formed which results in disruption of zinc absorption by the plant. Moreover, zinc absorption by plants is hampered by the presence of high levels of copper, iron and manganese ions in the soil solution.
Zinc deficiency in the soil of Bangladesh
Due to the high yielding paddy cultivation, most of the lands in Bangladesh are inundated for most of the year, so the zinc deficiency in the soil of this country is gradually increasing. According to the Soil Resources Institute, zinc deficiency exists in 2.8 million hectares of land in Bangladesh, which is more than one third of the total cultivable land. With the increase in the intensity of agriculture, this deficit has been increasing. In addition, calcareous soils, sandy soils, highly organic loam, saline soils with high pH, ​​and piedmont soils at the foot of hills are inherently deficient in zinc.