求翻译：黄一兰等研究结果[21]，仅表明从2月9日至2月27日，随移栽期的推迟，不同部位烟叶等级结构和质量发生改变，没有对不同播栽期条件下烟株生长发育规律进行研究，且播栽期是否还有进一步提早的可能，不同播栽期条件下病害发生规律等也还有待研究。是什么意思？

Huang Yilan and other findings [21], showed that only with the postponement of the transplanting period from February 9 to February 27, the hierarchical structure and quality of different parts of tobacco leaves to change, no development on the growth of tobacco plant in different conditions of seed

As a results of the study [ 21] show that only, from 2 to 2, 9, 27, and the deferred period the transplantation procedure, the different hierarchical structures and site tobacco quality, and there is no change to the conditions at different intervals the next smoke-free plant growth and development

Findings (21) and so on yellow orchid, only indicated from February 9 to February 27, along with transplants the time the postpone, the different spot leaf tobacco rank structure and the quality has the change, to differently has not broadcast plants under the time condition the smoke growth develop

Huang Yilan research results [21], only shows from February 9 to February 27, with the transplanting period of delay, changing the structure and quality of flue-cured tobacco in different parts, not under different sowing on growth and development of flue-cured tobacco research, and sowing are there

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