Norman Borlaug, known as the "Father of the Green Revolution," was an American agronomist and humanitarian who made significant contributions to agriculture. He is particularly renowned for his work in developing high-yielding varieties of wheat. This answer will explain why wheat is the correct answer to the question.

1. The Green Revolution:
The Green Revolution refers to a period of technological advancements in agriculture that took place in the mid-20th century. It aimed to increase agricultural productivity and combat hunger by introducing new farming techniques and high-yielding crop varieties. Norman Borlaug played a pivotal role in this revolution, and his work primarily focused on wheat.

2. Wheat Varieties:
Borlaug developed wheat varieties that were resistant to diseases, pests, and environmental stresses. These varieties had shorter stalks, better response to fertilizers, and higher yields compared to traditional wheat varieties. The improved traits of Borlaug's wheat varieties made them highly productive and suitable for different agro-climatic conditions.

3. Impact of Borlaug's Work:
The development and widespread adoption of Borlaug's high-yielding wheat varieties had a significant impact on global food production. These varieties played a crucial role in increasing wheat yields, reducing hunger, and improving food security in many parts of the world. Borlaug's work was particularly instrumental in countries like India, Pakistan, and Mexico, where his wheat varieties helped transform their agricultural landscapes.

4. Recognition and Appreciation:
Norman Borlaug's contributions to agriculture were widely recognized and appreciated. He received numerous accolades for his work, including the Nobel Peace Prize in 1970. The Green Revolution, driven by Borlaug's innovations, has been credited with saving countless lives and alleviating hunger in many developing countries.

In conclusion, Norman Borlaug developed highly recognized and appreciated varieties of wheat during his work as the father of the Green Revolution. His efforts in developing high-yielding wheat varieties revolutionized global agriculture, significantly increasing food production and improving food security.