EFFECT OF DIFFERENT RATES OF NPK FERTIZER ON BOK CHOY (Brassica rapa) AT ROYAL UNIVERSITY OF AGRICULTURE. ឥទ្ធិពលនៃកម្រិតជី N P K(20-20-15) ខុសៗគ្នាទៅលើដំណាំស្ពៃតឿនៅសាកលវិទ្យាល័យភូមិន្ទកសិកម្ម HENG CHHAINIT ហេង ឆៃនិត AGR HEN 2021 B1-570 Or. Phnom Penh RUA 2021 2021 Text IX.32P https://drive.google.com/file/d/1PeDxh_a8epKoAMf0h5PUeKbxlS73xoWU/view?usp=sharing