Xylem is the main tissue for water transport in plants, and the changes of hydraulic properties in which would affect plant water relations and fruit water accumulation. It remains unclear regarding the responses of xylem anatomy and hydraulic properties to water and salt stresses in tomato plants and their relationships with plant growth and fruit water content. We conducted a pot experiment in a greenhouse to investigate the responses of plant growth, fruit water content, and xylem hydraulic properties of a cherry tomato (Hong Baoshi) and a medium-fruited tomato (Beifan 501). There were three treatments, control with a soil water content (θ) of 75%-95% of field capacity (FC) and an initial electrical conductivity (EC) of 0.398 dS·m-1; water stress with θ of 75%-95% of FC (before flowering) and 45%-65% of FC (from flowering until maturity) and an EC of 0.398 dS·m-1; and salt stress with θ of 75%-95% of FC and an EC of 1.680 dS·m-1. Results showed that water and salt stresses decreased the cross-sectional stem area and xylem vessel diameter by 22.0%-40.7% and 10.0%-18.3%, respectively, and reduced the specific hydraulic conductivity of stem and the hydraulic conductivity of peduncle by 8.8%-41.1% and 12.9%-28.4%, respectively. Those changes inhibited plant growth and reduced aboveground fresh weight, fruit size, fresh weight and water content, with a more pronounced negative effect in the medium-fruited tomato. More-over, fruit water content was positively correlated with the specific hydraulic conductivity of stem and peduncle. In conclusion, water and salt stresses would inhibit plant growht, fruit fresh weight, and consequently tomato yield, due to their negative effects on xylem hydraulic properties of the tomato plant. Medium-fruited tomatoes are more susceptible to water and salt stresses than cherry tomatoes.
木质部是植株体内水分传输的主要通路,其水力特性的变化会影响植株的水分关系和果实的水分积累。目前关于番茄植株木质部解剖结构和水力特性对水分和盐分胁迫的响应及其与植株生长和果实含水量之间的关系尚不明确。本研究通过日光温室番茄盆栽试验,设置3个处理:对照,土壤含水量(θ)为75%～95%田间持水量(FC),初始电导率(EC)为0.398 dS·m-1;水分胁迫,开花前θ为75%～95% FC,开花后至成熟期θ为45%～65% FC,EC为0.398 dS·m-1;盐分胁迫,θ为75%～95% FC,EC为1.680 dS·m-1,研究了樱桃型番茄(红宝石)和中果型番茄(北番501)植株在水分和盐分胁迫下的植株生长、果实含水量以及木质部水力特性的变化。结果表明: 与对照相比,水分和盐分胁迫下茎秆横截面积和木质部导管直径分别减小了22.0%～40.7%和10.0%～18.3%,茎秆比导水率和桁架柄比导水率分别降低了8.8%～41.1%和12.9%～28.4%,抑制了植株生长,减少了地上部鲜重、果实大小、果实鲜重和含水量,且与樱桃型番茄相比,中果型番茄的降幅更大。此外,果实含水量分别与茎秆和桁架柄比导水率呈显著正相关。综上,番茄植株在水分和盐分胁迫下木质部水力特性指标减小,生长被抑制,果实鲜重显著降低,最终导致产量降低。其中,中果型番茄相较于樱桃型番茄对水分和盐分胁迫更敏感。.
Keywords: fruit water content; salt stress; tomato plant growth; water stress; xylem anatomy structure; xylem hydraulic property.