Research On Shading Tolerance Of Impatiens Balsamina,I. Balsamina 'chahua' And I. Wallerana

In order to investigate the effects of shading on the growth, Physiology, photosynthetic characteristic parameters, flowering, fruit and seed characteristics even the shading tolerance ability of three Impatiens materials, including Impatiens balsamina L. Impatiens balsamina L.'Chahua' and Impatiens wallerana Hook, f., an artificial shade experiment has been conducted. Four shading treatments (full exposure, CK; 25% shading treatment, S1; 50% shading treatment, S2; 75% shading treatment, S3) were applied. The research not only provide a theory basis for the research of garden plants shading tolerance, but also the cultivation and the arrangement in flower border of three Impatiens materials. The main results were as follows.(1) After shading, the height, basal diameter, first class branch number, leaf number, leaf area, biomass of Impatiens balsamina, I. balsamina 'Chahua' and I. wallerana have changed significantly (P<0.05). In general, the vegetative growth of I, balsamina and I. balsamina 'Chahua' were weaker than those of CKs', while the vegetative growth of I. wallerana was stronger than that of CK's. Moreover, the vegetative growth of three Impatiens matierials was affected badly when the shading treatment was over 75%.(2) We summarized 3 regression models about leaf area and leaf length*leaf width with regression analysis on leaf area, leaf length and leaf width measured at different period in vegetative growth of three Impatiens materials.I. balsamina:Y (LA) =24.928+0.606L*W;I. balsamina'Chahua':Y (LA)=21.123+0.613L*W;I. wallerana:Y (LA)=5.624+0.626L*W(3) After shading, the chlorophyll content of three Impatiens materials all showed a single-peak trend, while the SS, SP, MDA content all decreased. The decrease of chlorophyll a/b indicated that the increase of chlorophyll b content was the key point of the increase of chlorophyll content. In addition, with the increasing of shading degree and shading time, the variation trend became significant (P<0.05) gradually.(4) After shading, the Pn of I. balsamina S1, S2, S3 were 109.3%,79.0%,37.8% of their CK's; the Pn of I. balsamina 'Chahua' 65.5%,29.9%,21.0% of their CK's; the Pn of I. wallerana S1, S2, S3 were 162.0%,153.1%,44.6% of their CK's. Furthermore, the Pn of I. balsamina was significantly positively correlated (P<0.01) with Gs, WUE; the Pn of I. balsamina 'Chahua' was significantly positively correlated (P<0.01) with Gs, Tr, WUE, and significantly negatively correlated with Ci (P<0.05); the Pn of I. wallerana was significantly correlated with Gs (P<0.05) and Tr (P<0.01), and the rest were correlated each other (P<0.05).(5) After shading, the flowering phonology of I.-waller ana S1, S2 extended, while those of I. balsamina S1, S2 and I. balsamina 'Chahua' S1, S2 shortened. The early flowering stage in I. balsamina S3,I. balsamina 'Chahua' S3 and I. wallerana S3 delayed 18d,38d,44d compared to their CKs', respectively. However, there were no full-bloom stage and ending flowering stage in S3 of three Impatiens materials because of the individual flowering phenomenon. Furthermore, the flowering duration, flower amount, surviving rate, weight of single fruit, and seed number of single fruit of I. balsamina and I. balsamina 'Chahua' all decreased. On the other hand, the flower and seed index of I. wallerana all showed a single-peak trend except its dropping surviving rate. At the same time, the hundred-grain weight of three Impatiens materials agreed with the variation trend of the Pn.(6) By principal component analysis, we got four main components. The first principal component:basal diameter, leaf number, SS, MDA, Pn, Gs, SP; the second principal component:horizontal diameter of flower, surviving rate, flowering duration; The third principal component:chlorophyll content; The fourth principal component:Tr. The accumulative contributive rate was 89.100%, which represented most of the information content. The comprehensive evaluation about shading tolerance of three Impatiens materials was made by the fuzzy mathematics subordination function method, which showed that shading tolerance ability from high to low was I. wallerana>I. balsamina >I. balsamina 'Chahua'.