问题 问答题 简答题

简述作物产量形成的源库关系。

答案

参考答案:

源是制造同化物的器官,库是接纳同化物的部位,源与库共存于同一植物体,相互依赖,相互制约。作物要高产,需要库源相互适应,协调一致,相互促进。库大会促源,源大会促库,库小会抑制源,源小库就不能大,高产就困难。

作物产量形成的源库关系有三种类型:

(1)源限制型;

(2)库限制型;

(3)源库互补型,源库协同调节。

增源与增库均能达到增产目的。

单项选择题
阅读理解

The Great Barn Adventure

One morning when I was 11, I explored the town's abandoned round grain barn(谷仓). I found a chained sliding door that was wide enough for me to pass through.

Inside, there was a heavy smell of dead mice in the dark. After my eyes adjusted, I noticed a shaft (升降机井) that rose all the way to the top of the barn. On one side was a one­man elevator with a long rope and roller.

I stepped onto the platform and gave the rope a drag and the elevator began sliding up the shaft, but stopped halfway. After a brief panic attack, I noticed holes in the wall at regular intervals, forming a ladder. For reasons known only to an 11­year­old, I decided it would be better to go up than down. So, with shaking hands, I began climbing the wall.

After what seemed like forever, I reached the top of the shaft. I stood up, dusted myself off and found…absolutely nothing of interest. It was just an empty room with a ladder leading up to the roof. I climbed all the way up here for this? Then I noticed a fire extinguisher(灭火器),which I'd always wanted to shoot off. So this was the chance of a lifetime. I tried it, and, much to my surprise, the thing worked! It shot out a thick cloud of powder that instantly filled the room. I couldn't breathe. I was going to choke to death, and they'd probably never even find my body.

Luckily, I remembered the ladder to the roof. I climbed up, popped the straw roof and saw a bright blue sky.

I suddenly realized the dust and powder pouring out of the top could draw attention. So when the dust had settled, I climbed down and slipped out of the chained door. I'm not sure if I was more excited about being alive or about not being caught, but I ran all the way back home.

小题1:When the author got inside the barn, he ________.

A.noticed a man on the elevator

B.opened the chained sliding door

C.saw many dead mice in the dark

D.found a shaft leading to the top小题2:Which of the following is the right order of the author's adventure?

a. The elevator stopped halfway.

b. He entered the round grain barn.

c. He climbed to the top of the shaft.

d. He found a fire extinguisher and shot it off.

A.b-a-c-d      

B.a-c-b-d

C.c-a-d-b

D.b-c-a-d小题3:After getting out of the chained door, the author might feel ________.

A.inspired

B.relieved

C.surprised

D.disappointed