nitrogen-free medium meaning in English

无氮培养基

In nitrogen - free medium , the logarithmic phase of the strain w12 was about 13 - 48 h . in logarithmic period its doubling time was 2 - 4 h in nitrogen - free medium , 0 . 9 - lh when enough nk
在无氮培养基上该菌在13h后进入对数生长期，并持续至48 52h ，这期间其生长代时为2 - 4h ，有氮培养基上为0 . 9 - 1h 。
In this study , 5 rhizosphere soil samples of wheat , maize , ryegrasses and willow tree were collected from campus of china agricultural university and beijing chaoyangqu , respectively . a total of 29 isolates were selectively obtained from these rhizosphere soli samples based on their growth on nitrogen - free medium and their resistance to 100 for 10 - 15 min
本文在中国农业大学科学园区采集了小麦和玉米的根际土，从北京市朝阳区洼里分别选择不同环境采集2个黑麦草根际土壤样品和1个柳树根部的土壤样品，分别从这5个土壤样品中分离固氮的芽孢杆菌。