I have got low marks in chem & physics therefore can i calculate the English, Bio & agri marks for bsc agri??

Yes, generally, for BSc Agriculture admissions, Physics, Chemistry, and Biology (PCB) are often core subjects, but some universities may consider English and Agriculture (if taken as a subject) marks as well, in addition to the PCB aggregate. The specific weightage of each subject and whether English and Agriculture are considered may vary between universities and entrance exams