高温环境下空气湿度对花期番茄生长及根系分泌的调节作用

Regulating Effect of Air Humidity on Tomato Growth and Root Exudates during Flowering Period under High Temperature Condition

以番茄品种“金冠5号”为试材,设置2个日动态温度(T)水平即日最高气温/日最低气温分别为32℃/22℃和38℃/28℃、3个空气相对湿度(RH)水平(50%±5%、70%±5%和90%±5%)和4个持续时间(3d、6d、9d和12d),并以25℃/15℃、50%±5%为对照(CK),分别测定各处理结束后0d、7d、14d、21d和28d时植株叶片的净光合速率(Pn)、植株总干重(Wtotal)、根系干重(Wroot)和活力(Rv)以及根系土壤中低分子量有机酸(LMWOAs)的类型和浓度,以探究高温环境下空气湿度对花期番茄生长及灾后恢复的调节机制。结果表明:(1)高温下植株的Pn和Rv下降,但根冠比和LMWOAs显著提高,且32℃处理下各指标值显著高于38℃,提高RH至70%可显著提高植株的Pn、Wroot和根冠比。(2)花期番茄主要分泌草酸和琥珀酸,高温下草酸、苹果酸、乳酸、乙酸和丙酸分泌量增加,酒石酸和甲酸分泌量减少。(3)环境温度和湿度均与LMWOAs呈显著负相关关系,Pn、Wroot、Wtotal和Rv与LMWOAs呈显著正相关。(4)高温下提高空气湿度至70%可增加Pn和Wroot,并促进根系分泌LMWOAs,有利于灾后番茄的恢复生长,但空气湿度达到90%则降低了叶片Pn和Wroot,加剧了高温对植株的损伤,不利于灾后恢复。因此,70%左右空气湿度可以在一定程度上缓解高温对番茄苗造成伤害。

Increasing air humidity to relieve high temperature stress is one of the common measures in greenhouse management.To study the regulation mechanism of air relative humidity on tomato growth and disaster recovery in high temperature conditions,the tomato variety"Jinguan 5"was used as the experimental material.This experiment was carried out at the Agricultural Experimental Station of Nanjing University of Information Science and Technology from September 2018 to January 2019.Two dynamic temperature(T)levels(daily maximum temperature/daily minimum temperature such as 32℃/22℃and 38℃/28℃),three relative humidity(RH)levels(50%±5pp,70%±5pp and 90%±5pp)and four stress days(3d,6d,9d and 12d)were set,and 25℃/15℃and 50%±5pp were taken as control(CK).The net photosynthetic rate(Pn),total dry weigh t(Wtotal),root dry weight(Wroot),root activity(Rv),and the type and concentration of low molecular weight organic acids(LMWOAs)in root soil were measured at 0,7,14,21 and 28d after treatment.The results showed that:(1)Pn and RV decreased,but root shoot ratio and LMWOAs increased significantly under high temperature,and each index value under 32℃treatment was significantly higher than 38℃,RH increased to 70%,Pn,Wroot and root shoot ratio increased significantly.(2)At flowering stage,tomato mainly secreted oxalic acid and succinic acid.At high temperature,oxalic acid,malic acid,lactic acid,acetic acid and propionic acid increased,while tartaric acid and formic acid decreased.(3)T and RH were negatively correlated with LMWOAs,and Pn,Wroot,Wtotal and Rv were significantly positively correlated with LMWOAs.(4)Increasing RH to 70%at high temperature condition could increase Pn and Wroot and promote the root system to secrete LMWOAs,which was conducive to the recovery and growth of tomato after disaster.However,when RH reached to 90%,Pn and Wroot would be reduced,which will aggravate the damage of high temperature to plants and is not conducive to the recovery after disaster.Therefore,about 70%air humidity can alleviate the high temperature disaster to a certain extent.