RESUMO
<p><b>OBJECTIVE</b>To study the effects of sowing date on morphologic characteristics, yield and quality of Radix Isatidis, in order to provide a basis for selection of the suitable sowing date.</p><p><b>METHOD</b>The experiment was carried out in a randomized complete block design arranged in split plot, the phonological period of Isatis indigotica was investigated and the morphological indexes, yield and quality at harvest were measured and determined by correlation and variance analysis.</p><p><b>RESULT</b>The different sowing dates showed a great effect on phonological period of I. indigotica. The biological characteristics, yield and active components of Radix Isatidis were negatively correlated with the sowing date, and the difference of morphological characteristics, yield and active compositions with sowing date was significant.</p><p><b>CONCLUSION</b>The suitable sowing date of I. indigotica was during the period of time from late March to beginning of the April in Fuyang area, and considering the factors of rational rotation, the time cloud delayed until late May to the beginning of June.</p>