The episode with the braid illustrates the changes that China was experiencing in the early twentieth century. Though Buck's hold on chronology seems to be somewhat unreliable, there's no doubt that China in the early twentieth century was caught between the competing values of the indigenous culture and the Western imperialists who effectively ran the country.

For centuries, the wearing of a pigtail or braid wasn't just a haircut: it symbolized subservience in this rigidly hierarchical society. To remove a braid would've been considered an act of insubordination against one's social betters. Wang Lung has clearly internalized this age-old tradition, and he is horrified by the very suggestion that he'd look much better without the braid. The barber's advice foreshadows the immense social changes that will sweep Chinese society in due course, culminating in the Communist seizure of power and the subsequent establishment of the People's Republic of China in 1949.

Tradition. When Wang Lung in the first chapter goes into the town to claim his wife, he goes to the barber to make himself more presentable for his first meeting with his future wife. Whilst the barber is shaving Wang Lung's upper forehead, he comments:

This would not be a bad-looking farmer if he would cut off his hair. The new fashion is to take off the braid.

However, Wang Lung, horrified, draws back, saying that he could not cut his braid off without asking his father. This is a novel where old ways collide with new habits and fashions, and Wang Lung, as befits a character whose attachment is to hard work and the earth, refuses to cut his braid off because he is a representative of tradition. Symbolically, the braid therefore shows us the kind of character that Wang Lung is and the way that he will not be swayed by the modern fads and fashions that others feel are so important.