Drought tolerance of intergeneric hybrids between Chrysanthemum morifolium and Ajania przewalskii

The drought tolerance of the chrysanthemum (Chrysanthemum morifolium Ramat.) 'Zhongshanjingui', Ajania przewalskii Poljakov and two independent hybrid lines of 'Zhongshanjingui' x A. przewalskii were compared. The intergeneric hybrids and paternal parent (A. przewalskii) showed higher tolerance to drought than the maternal parent (Zhongshanjingui) during continuous drought stress conditions. After 10 days of drought treatment, when the water content of the growth medium decreased to 0.8%, the female parent exhibited the most severe wilting (the maximum index value of 3.0), whereas the male parent and two hybrid lines showed moderate wilting (wilting indices of 1.9, 2.2 and 2.4, respectively). Twelve hours after rewatering of the drought-stressed plants, the chrysanthemum leaves failed to recover, whereas leaves of the hybrids and A. przewalskii recovered turgor. Under drought conditions, the hybrids and A. przewalskii showed superior root growth to that of chrysanthemum with respect to both the rate of relative root growth and root dry weight per plant. Enhanced drought tolerance was also correlated with an increase in free proline and a decrease in malondialdehyde contents. The results indicated that the hybrids showed morphological and physiological responses to drought conditions inherited from A. przewalskii, and that intergeneric hybridization is a favorable means to introduce multiple resistance characters of relative germplasm into chrysanthemum. (c) 2012 Elsevier B.V. All rights reserved.