Look at the pictures and write the words. Trees also have to go to the third grade.

At the Xi World Expo, all kinds of flowers are in full bloom, with bright colors and beautiful scenery. But I saw a strange thing. The big trees here also "dripped".

When you visit the Expo Park, you can see that many trees are hung with plastic bags. Connected to the plastic bag is a thin and long tube similar to an infusion tube, which is directly inserted into the trunk of a tree. Does the big tree also need "drip"? Is the tree sick? Is that bag full of medicine? It's so hot, isn't it just to replenish water for the trees? Just ask mom and dad after guessing so much.

Dad told me that many of these trees are transplanted from all over the world, which are not suitable for the climate and water and soil here and are easy to get sick. Injecting them with some special liquids can ensure the normal growth of trees. My mother told me that the climate in Xi 'an is dry, and there may be water in plastic bags, so that trees can grow more luxuriantly and the World Expo will be more beautiful.

Oh, I see. It turns out that trees can't stand the dry and hot weather in Xi 'an. I carefully observed those bags, which contained some plant nutrient solution and some pure water. The gardeners there not only water the trees in the morning and evening, but also replenish water during the day to promote the growth of the trees. Later, I found that those slender pipes not only lead to the trunk, but also to the ground. Even flowers and plants need to be supplemented with nutrition and water. No wonder the flowers of the World Expo can bloom so brilliantly in the scorching sun.

It's really weird. This is the first time I have seen such a phenomenon. After going back, I found some detailed information from the Internet: those plastic bags are mainly filled with nutrient solution rich in trace elements such as iron, manganese and magnesium, and rooting powder, nitrogen fertilizer and phosphorus fertilizer can also be added. Through the root pressure and transpiration tension of trees, liquid can be transmitted to the whole body of trees horizontally and vertically. This "drip" way can turn the leaves of trees into dark green, restore their growth ability, and improve their survival rate and disease resistance. In addition, the nutrient solution does not pollute the environment, and the pinhole is small, which has little effect on the growth of trees.

Now you understand that big trees also need to "drip". Coincidentally, in the eighth issue of Science Illustrated, I saw that the city wall also needed to "drip water" to ensure its durability. It's amazing how big the world is!