Farmerbrie by critical irrigation period do you mean stages in their development when they need water the most?
If so, I have compiled a list of some critical watering periods of some vegetables:
* Beans and Peas: during flowering and the development of their pods.
* Cabbage, Broccoli, and Cauliflower: during head development.
* Carrots, Onions, and Radishes: during root development.
* Cool Season Vegetables (like greens): during periods of intense heat.
* Cucumbers: from flowering to the development of their fruits.
* Eggplant: uniform throughout season is best.
* Germinating Seeds: water germinating seeds frequently, but lightly to avoid washing them away.
* Melons: during flowering and early fruit development.
* Peppers: from planting to fruit set and enlargement; uniform throughout season is best.
* Potatoes: during tuber set and enlargement.
* Squash: during flowering and fruit development.
* Sweet Corn: during silking, tasseling, and ear development.
* Tomatoes: especially critical during flowering, fruit set, and fruit enlargement; uniform throughout season is best.