水杨酸对大花三色堇幼苗耐热性的影响

大花三色堇性喜冷凉、忌酷热。该研究以大花三色堇3个自交系08H 、HAR 和 E01为材料,分别测定了40℃高温处理4、8和12 h 时不同基因型大花三色堇幼苗的生理指标,以及不同浓度(0.1、1、2 mmol?L-1)水杨酸预处理对热胁迫下大花三色堇幼苗耐热性的影响。结果表明：在高温胁迫下大花三色堇电解质外渗量增加,随着处理时间的延长,电解质外渗更多,可溶性糖含量先增加后降低,POD 酶活性先提高后降低；与其他2个自交系相比,HAR 表现出较好的耐热性,其可溶性糖含量、POD 酶活性的增加均较高,而电解质外渗率偏低；与对照相比,3种浓度 SA 预处理均显著降低了大花三色堇幼苗的电解质外渗率,增加了幼苗体内可溶性糖含量,提高了大花三色堇的幼苗体内脯氨酸含量和 POD 酶活性；其中1 mmol?L-1的 SA 预处理对高温胁迫下大花三色堇幼苗体内可溶性糖的含量增加最高,最大程度减缓幼苗体内的电解质外渗量,08H 和 HAR 的脯氨酸含量和 POD 酶活性达到最大值。而对 E01而言,0.1 mmol?L-1的水杨酸预处理的脯氨酸含量和 POD 酶活性最高。该研究结果探讨了高温胁迫下不同基因型大花三色堇幼苗的生理表现,以及外施水杨酸对增强大花三色堇幼苗耐热性的效果,为大花三色堇抗热栽培提供重要的基础资料。

Effects of salicylic acid on heat resistance of Viola × writtrockiana seedlings

Originated from northern Europe, Viola × wittrockiana is accustomed to the cool climate but cannot stand heat stress during its growth and development stages. Three inbred lines of Viola × wittrockiana, namely 08H, HAR and E01 were adopted as trial materials to investigate the physiological and biochemical performance of Viola × wittrockiana after the seedlings were treated with 40 ℃ for 4, 8 and 12 h respectively. The results showed that electrolyte leakages of all three Viola × wittrockiana seedling leaves increased under the heat stress, compared to the controls. And the longer the time of heat stress was, the more the electrolytes leaked. But the soluble sugar, proline content and activity of POD of Viola × wittrockiana increased firstly then decreased with heat stress time prolonged. The peaks of the biochemical indi-ces varied with the index and genotypes. Compared with two other genotypes, the electrolyte leakage rate of HAR was lower under all of heat stress conditions. But its POD enzyme activity was higher all the time. The soluble sugar content and proline content of HAR were up to the highest under 40℃ for 8 h and 4 h respectively. All of these biochemical indi-ces revealed ‘HAR’ had the strongest heat resistance. Furthermore, in order to investigate effects of salicylic acid on heat resistance of Viola × wittrockiana seedlings, three genotypes seedlings were pretreated with different salicylic acid concentrations (0.1, 1 and 2 mmol?L-1) before they treated with heat stress (40 ℃ for 12 h). Compared to the con-trast, the electrolyte leakage rates of Viola × wittrockiana seedlings reduced significantly after treated with SA. The elec-trolyte leakage rates of all genotypes were up to the lowest when the seedlings pretreated with 1 mmol?L-1 SA. But the soluble sugar contents of Viola × wittrockiana increased when seedlings pretreated with SA, the highest value appeared for three genotypes with SA pretreatment by 1 mmol?L-1. The proline contents of seedling also increased after SA pre-treatment, but the most suitable SA concentrations were different among genotypes. For 08H and HAR, the most effec-tive concentration of SA was 1 mmol?L-1, but for E01 it was 0.1 mmol?L-1. With respect to POD activity of Viola × wittrockiana seedlings, it also increased significantly for all genotypes when the seedlings pretreated with SA. But the in-creasing for different genotypes varied with the SA concentration. Pretreatment with 0.1 mmol?L-1 was best for E01, and 1 mmol?L-1 pretreatment was the greatest for 08H and HAR. In short, pretreatment with 1 mmol/ L SA was suggested for application to improve heat resistance of Viola × wittrockiana seedling for it could increase the content soluble sugar and reduce the amount of electrolyte leakage of leaf cell more significantly than the other SA concentration (0.1 and 1 mmol?L-1) under heat stress. The results showed the physiological performance of different Viola × wittrockiana geno-types under heat stress and effects of SA on heat resistance of Viola × wittrockiana seedlings, and provides the basic data for thermal cultivation and breeding of Viola × wittrockiana .