黄瓜嫁接愈合期阶段性光照强度筛选及作用机制初探

Screening and Mechanism Exploration of Light Intensity during Grafting Healing of Cucumber

为探究嫁接愈合期不同光照强度对嫁接愈合的影响,并筛选黄瓜嫁接愈合期最精确的光照强度,以黄瓜为接穗、南瓜为砧木进行顶插嫁接后,分3个阶段(1~3 d、4~6 d、7~9 d)进行递进试验。每个阶段给与不同的光照强度,采用快速叶绿素荧光技术辅以嫁接愈合表型指标,对嫁接愈合的实时效果进行有效评价与分析。结果表明,随光照强度增强,黄瓜嫁接愈合期接合部直径在第一阶段(1~3 d)和第三阶段(7~9 d)先上升后下降,但第二阶段(4~6 d)接合部直径无明显变化。嫁接愈合期第一阶段(1~3 d)和第三阶段(7~9 d)的砧木和接穗子叶的Y(Ⅱ)(实际光化学量子效率)和qP(PSⅡ电子传递速率)随着光照强度的增强先上升后下降,并且分别在50、150μmol/(m~2·s)的光照强度处理下取得最大值,而第二阶段(4~6 d)接穗子叶的Y(Ⅱ)和qP均在100μmol/(m~2·s)的光照强度下取得最大值。第一阶段(1~3 d)和第二阶段(4~6 d)Y(NO)(PSⅡ非调节性能量耗散)随光照强度增强则先下降后上升。通过隶属函数-雷达分析法进行综合评价,得出1~3 d、4~6 d、7~9 d分别在50、100、150μmol/(m~2·s)的光照强度下愈合效果最好。综上所述,嫁接愈合期间1~3 d、4~6 d、7~9 d分别给与50、100、150μmol/(m~2·s)的光照强度最有利于嫁接愈合。另外,嫁接愈合期适当增强光照强度能够增加接合部愈伤组织数量,提高砧木和接穗子叶光合效率和电子传递速率,同时提升嫁接苗对嫁接胁迫的自我调节能力,有效促进黄瓜嫁接愈合。

In order to investigate the effect of different light intensity on grafting healing and select the most accurate light intensity during grafting healing of cucumber,with cucumber as scion and pumpkin as rootstock,the top grafting was carried out,followed by tests in three stages(1—3 d,4—6 d,7—9 d).Different light intensity was given at each stage,and the real-time effect of grafting healing was effectively evaluated and analyzed by using rapid chlorophyll fluorescence technique supplemented with grafting healing phenotype indexes.The results showed that,with the increase of light intensity,the diameter of junction at the first stage(1—3 d)and the third stage(7—9 d)increased first and then decreased,but diameter of the junction at the second stage(4—6 d) did not change significantly.The actual photochemical quantum efficiency[Y(Ⅱ)]and PSⅡ electron transfer rate(qP)of rootstock and scion cotyledons in the first(1—3 d)and third(7—9 d)stages of grafting healing increased first and then decreased with the increase of light intensity,and reached the maximum values at light intensity of 50,150 μmol/(m~2·s),respectively.In the second stage(4—6 d),the actual photochemical quantum efficiency[Y(Ⅱ)]and PSⅡ electron transfer rate(qP)of scion cotyledons both reached the maximum values at light intensity of 100 μmol/(m~2·s).In the first stage(1—3 d)and the second stage(4—6 d),the non-regulatory energy dissipation of PS Ⅱ[Y(NO)]decreased first and then increased with the increase of light intensity.Comprehensive evaluation by membership function-radar analysis method showed that 1—3 d,4—6 d,7—9 d had the best healing effect under the light intensity of 50,100,150μmol/(m~2·s),respectively.In conclusion,light intensity of 50,100,150 μmol/(m~2·s)at 1—3 d,4—6 d,7—9 d during grafting healing was the most favorable.In addition,enhancing light intensity during grafting healing period could increase the number of calluses in the junction,improve the photosynthetic efficiency and electron transfer rate of cotyledons of rootstock and scion,and improve the self-regulation ability of grafted seedlings to grafting stress,effectively promoting the grafting healing of cucumber.