Physiological Responses Of Different Spathiphyllum Cultivars Under Low Temperature Stress And Cold Resistance Evaluation

Spathiphyllum floribundum belongs to Araceae genus spathiphyllum. It has beautiful flowers and leaves and long florescence that make it to be excellent potted flowers and important cut flower species. It has a broad market prospect because it’s economic value and ornamental value. Spathiphyllum floribundum has high requirement for temperature, so it often suffers cold stress in the production process which reduces the flowers quality. The materials of this research are six spathiphyllum cultivars. Determination the biochemical indexes which include the relative electric conductivity, MDA content, SOD activity, soluble sugar content, soluble protein content and proline content under different temperatures cold stress and different times cold stress. By principal component analysis and membership function calculating, we have made the six spathiphyllum cultivars’comprehensive evaluation of cold resistance in two methods of cold stress. We have select two spathiphyllum cultivars which have different cold resistance according to the comprehensive evaluation to observe the leaf epidermis’ stomata. The purpose of the research is not only to reveal the spathiphyllum’ physiological comparative analysis in the process of resisting cold, but also to provide theoretical basis and reference for cultivation and breeding of new spathiphyllum cultivars which can resist cold. The mainly results showed as following:(1) In different temperatures cold stress, as the temperature dropped, the six spathiphyllum cultivars’physiological indexes comparative analysis are very close, but the rate and magnitude of comparative analysis are different from each other. As the temperature dropped, the relative electric conductivity and MDA content increased; the SOD activity, soluble sugar content, soluble protein and proline content increased firstly and then decreased. In the whole process of cold stress, the spathiphyllum’Superpetite’ has low relative electric conductivity and MDA content, big SOD activity and high soluble sugar content; the spathiphyllum ’Petite’ has low soluble protein content and proline content; the spathiphyllum ’Mojo’ has high relative electric conductivity and MDA content; the spathiphyllum’Sweet chico’has low relative electric conductivity, big SOD activity, high soluble protein content and proline content; the spathiphyllum ’Vicki’has small SOD activity.(2) In different times cold stress, as stress time extension, the six spathiphyllum cultivars’physiological indexes comparative analysis are very close, but the rate and magnitude of comparative analysis are different from each other. As stress time extension, the relative electric conductivity and MDA content increased; the SOD activity, soluble sugar content, soluble protein and proline content increased firstly and then decreased. In the whole process of cold stress, the spathiphyllum’Superpetite’has low relative electric conductivity and MDA content, big SOD activity, high soluble sugar content, high soluble protein content and proline content; the spathiphyllum ’Mojo’has high relative electric conductivity and MDA content, samll SOD activity, low soluble sugar content, low soluble protein content and proline content; the spathiphyllum’Sunshine dream’ has small SOD activity, low soluble protein and proline.(3) The research of correlation of physiological indexes suggested that six physiological indexes’correlation is complex and closed under different temperatures cold stress and different times cold stress, but it not totally consistent between two methods of cold stress, maybe the mechanism of spathiphyllum cultivars’ resisting cold isn’t same. To be sure is that, the relative electric conductivity and MDA content showed a strong positive correlation. So there are some overlaps and oversights in the information which is provided by six physiological indexes under two methods of cold stress. The cold resistance of plant is the result of many physiological indexes’ comprehensive function. It is necessary to analyze integrating physiological indexes for evaluating the cold resistance of spathiphyllum comprehensively and accurately.(4) By membership function calculating on the basic of principal component analysis, we have calculated comprehensive evaluation value. In the different temperatures cold stress, the sequence of the six spathiphyllum cultivars cold resistance is’Super petite’>’Vicki’>’Sweet chico’>’petite’>’Sunshine dream’>’Mojo’; In the different times cold stress, the sequence of the six spathiphyllum cultivars cold resistance is’Super petite’>’Sweet chico’>’petite’>’Vicki’>’Mojo’>’Sunshine dream’. In general, the cold resistance of’Super petite’is strongest, the cold resistance of’Sunshine dream’and’Mojo’are relatively weak.(5) By observing the epidermis’stomata of two spathiphyllum cultivars which have different cold resistance, we have found that the epidermis’stomata density of’Mojo’ which has strong cold resistance is far more than ’Sweet chico’ which has weak cold resistance. The leaf anatomical structure suggested that the degree of differentiation of two spathiphyllum cultivars’ palisade tissue and spongy tissue is not high,’Sweet chico’ is slightly high than’Mojo’.