I will enlist down below the  top recommended books for the horticulture entrance examination...

1. Horticulture at a glance by B.B.Singh
2. Essence of Horticulture
3. General Agriculture by M.S.Rathore
4. Objective Floriculture and Landscaping
5. Deep into Horticulture by Satyanarayan Gupta

Thank you. Best wishes.