hi,

see tamil nadu agriculture university provides admission in diploma in agriculture or horticulture, the eligibility criteiria is candidates need to pass 10+2 course with physics chemistry biology or physics chemistry botany zoology. or the candidates need to pass hsc  under vocational stream and  have studies biology and agriculture practices in hsc level.  the number of limit to attempt the qualifying exam i.e hs or hsc under vocational stream is 3 times for sc/st/sca communities, for other community it is 2 time. there is no maximum age limit applied for sc/st/sca candidates. for other communities candidates age limit should be less than 21 years as on 1st july of respective years. you may check the below link to know in details,

http://www.tnau.ac.in/admission/2019/diploma/Diploma_Information_Brochure_2019.pdf