樱桃番茄对根际外源碘的吸收及生理反应特性

Absorption of exogenous iodine in rhizosphere and its effects on physiological parameters of cherry tomato plants

关键词:  碘  樱桃番茄  吸收  根系活力  叶绿素  光合作用

Key words:  iodine  cherry tomato  absorption  root activity  chlorophyll  photosynthesis

摘要:

在深液流水培的营养液中添加浓度为1.0～6.0 mg•L 1的碘离子栽培樱桃番茄。根系、叶片和果实的碘含量均表现随着I 浓度提高而增加的趋势。根系的碘含量在I 处理后1周迅速增加；第2周降低，此后呈现逐渐增加的趋势，而且中高浓度处理（3.0～6.0 mg•L 1）的变化趋势比低浓度处理（1.0～2.0 mg•L 1）明显。叶片碘含量在处理后3周内随着时间的延长而明显增加；第3周以后，高浓度处理（4.0～6.0 mg•L 1）的叶片碘含量增加趋于平缓，而中低浓度处理（1.0～3.0 mg•L 1）的叶片碘含量变化不明显。根系和叶片中的碘浓度在1.0 mg•L 1浓度处理是根＞叶，在2.0～6.0 mg•L 1浓度处理的前期是根＞叶，后期是叶＞根，说明碘在根系积累到一定量以后才向叶片转移。对成熟果实的碘含量分别与处理后1～6周的叶片和根系的碘含量作单因素和双因素回归分析，说明I 处理后第1周是影响果实碘含量的最重要时期，利用叶片和根系的碘含量，根据一元二次回归方程可预测成熟果实的碘含量。2.0～6.0 mg•L 1浓度处理对根系的TTC还原量影响显著，这种影响主要表现在营养液加I 后3周以内。低浓度处理（1.0～2.0 mg•L 1）对叶绿素含量无显著影响，中高浓度处理（3.0～6.0 mg•L 1）显著降低叶绿素含量。2.0～6.0 mg•L 1浓度处理后2周，叶片的净光合速率、气孔导度、胞间CO2浓度、蒸腾速率均显著降低，而气孔限制值显著增高。

Abstract:

Cherry tomatoes(Lycopersicon esculentum var.cerasiforme)were cultured in deep flow hydroponic solution supplemented with graded levels(1.0-6.0 mg•L 1)of iodide(I ). The results showed that the iodine content in roots，leaves and fruits increased with increasing of I concentration. After I treatment，initially，the iodine content in roots increased rapidly for the first week；a decrease in the second week followed；and afterwards，a tendency of gradual increase was observed，with more significant changes at higher concentrations of I (3.0-6.0 mg•L 1) as compared to lower ones(1.0-2.0 mg•L 1). During the first three weeks after the I treatment，the iodine content in leaves increased significantly with the passage of time；after the third week，the increase tended to slow down for the plants treated with high concentrations of I (4.0-6.0 mg•L 1)，while no significant changes were found at medium or low ones(1.0-3.0 mg•L 1). For plants with I treatment of 1.0 mg•L 1，the iodine content in roots was higher than that in leaves；for I treatment of 2.0-6.0 mg•L 1，the iodine content in roots was higher than that in leaves at the early growth stage，but lower than leaves at the later growth stage，which suggested that iodine did not transfer to leaves until it had accumulated in the roots to a certain amount. Making mono factor and two factor regression analyses respectively of the correlation between the iodine content in ripen fruits and that in the leaves and the roots after I treatments of 1-6 weeks，we found that it was the first week after I treatment that the iodine content in fruits was affected most，and the iodine content in ripen fruits could be predicted with the iodine content in leaves and roots using the dualistic linear regression equation. The I concentration of 2.0-6.0 mg•L 1 significantly affected the deoxidize amount of triphenyl tetrazolium chloride(TTC) in roots，and the influence mainly appeared within the first three weeks after adding I to the solutions. The low concentrations of I (1.0-2.0 mg•L 1) did not affect chlorophyll content significantly，but the medium or high concentration of I (3.0-6.0 mg•L 1) significantly reduced it. Two weeks after treatment with I concentration of 2.0-6.0 mg•L 1，the photosynthetic rates(Pn)，stomatal conductance(Gs)，intercellular CO2 concentration(Ci)，transpiration rates(Tr)significantly reduced，while the stomatal limitation values(Ls) increased significantly.