[Effects of drought stress at the bud stage on quality of cut lily.]

Under the climatic conditions of the central Yunnan, with oriental lily cultivar 'Sorbonne' as material, the influences of different degrees of drought stress on physiological and biochemical changes of leaf and on quality of cut flowers after re-watering during the growth of bud were studied. The results showed that as the period of drought stress extended, the levels of leaf relative water content and chlorophyll content decreased significantly, while the stomatal density, MDA and proline content increased. Under mild drought, MDA increased slowly while it rose rapidly in the later stage of moderate drought stress, indicating that severe drought aggravated harm to the plasma membrane and ultimately affect the synthesis of MDA. Proline only experienced some slight changes in early period of mild drought, however, it increased sharply under severe drought conditions, which indicated that the sensitivity of proline to water deficit was lower than that to MDA. From re-watering to flowering, the effects of drought during bud growth reflected abnormal flowering traits. Compared with the normal group, there were significant differences in shoot growth, plant height, flower diameter, length and width of petal and flower pigment content. All indicators were in verse relation with the length of drought stress period because a longer drought period resulted in shorter plants, smaller flowers, shallower color. The differences among seven treatments during the flowe-ring stage of leaf morphology (length and width) were not significant. The drought during bud stage resulted in the delay of the flowering time, and the flowering quality of plants experiencing severe drought stress could not return to the normal levels even after re-watering. Overall, mild drought during early period had small influence on the quality of lily cut flowers as well as the grade of flo-wering branches. Under moderate or severe drought, the quality of cut flowers declined dramatically and even lost their commercial values.