I’ve only seen it spelled as one word “Yuan Longping”. By the way, “which is developed by” is not the correct tense; it should be “which was developed by”. Here, this is the passive voice in the past (not an adjective in the present). We can also use a reduced relative clause saying simply “hybrid rice, developed by Yuan Longping”.

Yuan Longping is correct. 中国名字翻译成为英文时，按照汉语拼音来书写，姓和名的首字母大写，其中名字的拼音要写在一块。 Professor Yuan Longping is one of the most important agricultural scientists who was committed his whole life to developing high-yielding hybrid rice. Due to his and many other scientists' work, China's rice production has increased significantly, helping maintain China's self-sufficiency in cereals. 袁隆平教授是“杂交水稻之父”、中国工程院院士以及“共和国勋章”获得者，他是最重要的农业科学家之一，他毕生致力于高产杂交水稻的研究。感谢他和其他许多科学家的研究，中国的大米产量有了显著增加，袁隆平院士的研究帮助中国提高并保持了粮食自给率。

你好， 一般翻译三个字的名字，姓氏和名分开来翻译会更好。 所以就是 Yuan Longping。 希望对你有帮助，谢谢。

Yuan(袁)是姓，Longping(隆平)是名。

第二个比较好