Let's start by talking about phototropism.

让我们先来谈谈向。

Auxin will always move away from the light in positive phototropism.

在正向中，生长素总是会远离线移动。

In other words, how did phototropism come to be?

换句话说，趋是如何形成的？

And two big things that you should understand about plants are phototropism.

关于应该理解的两个重要概念之一是向。

Negative phototropism would be growing in the other direction.

负向就是朝相反方向生长。

And so immediately when you plant a seed, the roots are going to show negative phototropism.

所以当种下一颗种子时，根部会立即表现出负向。

The two plant ones we'll talking about are phototropism and then photoperiodism.

我们要讨论的两种行为是趋和周期。

And so let's start with phototropism.

让我们从趋开始讲起。