Loquats are known to wilt for a variety of reasons. Some new leaf growth may become wilted and possibly die back or some leafs may fall off. Most reasons are problems with the tree health, but not always. Loquats can wilt when putting out new growth. The energy required to produce new foliage can stress the older leaves causing them to wilt. They sometimes will die, but the new growth is fine or other times the wilting leaves come back. Its difficult to tell what is happening to your tree from a picture of wilted leaves. It could be one of many things. Having seen this regularly I wouldn’t worry about the tree yet, but since it is young make sure its being watered adequately. The best way to water is deeply to encourage a strong root system. Allow the soil to briefly dry between waterings.
Don’t be alarmed just yet, unless there are any other issues besides the wilting. These are very hardy trees and will come out of shock and be thriving plants once again if cared for properly.
Here is a link to some common Loquat leaf wilt issues, although I don’t think these are your issues its good to be aware of them in any case: http://homeguides.sfgate.com/causes-drooping-loquat-tree-51266.html
Most soils are suitable for Loquats, and either shade or sunshine permit good growth. A sunny site with rich soil may be best. Though drought-tolerant, it does better if given some summer watering. Especially during the warm and dry summer the trees can quickly dry out and produce wilting foliage. Pest and disease problems are minor. Pruning to thin the crown is advisable. Loquats enjoy warm-temperate and subtropical climates. A lone Loquat specimen will set fruit, but cross pollination from more than one will increase yields.