Humans aren’t plants, it turns out; we just raise ‘em.
Literally: grain* / drop – grain* / drop – spicy / unpleasant – bitter / suffer
Alternately: Hard, steady work. To carry on with plain, painstaking, long-term labor. Elbows greased and noses to the grindstone. The image is of the farmers’ work that goes into producing each individual grain of rice that goes on to become someone’s food.
Notes: This phrase comes to us from the poetry of Tang-era politician-poet Li Shen (Japanese 李紳, Ri Shin). It is apparently a contraction (a yojijukugoification?) of the poetic line 粒粒皆辛苦. (The 皆 is probably pronounced mina in Japanese in this case.)
As usual, the doubled character 粒粒 may be replaced with the doubling mark, 粒々.
* In this case, “grain” refers to “a small piece of something,” e.g. a grain of sand or grain of rice, rather than cereals or legumes.