Effects of physical stresses on radish seed germination and growth

In this work we explore the consequences on variable magnetic fields applied to radish seeds (Raphanus sativum L.) on germination and seedling growth. Three, different alternate magnetic fields have been tested having a high intensity, 40 mT, at very low frequency, 0.2 Hz (B0.2), a low intensity, 577 µT, at low frequency, 370 kHz (B370), and a very low intensity, about 250 nT, at ultra high frequency, 900 MHz (RF900). These last generate electromagnetic waves which are nowadays very used for mobile communications. Groups of uniform radish seeds were exposed to alternate magnetic fields at three duration time values: i) 120 h (BO.2/1), 260 h (B0.2/2) and 360 h (B0.2/3) at high intensity and very low frequency, 0.2 Hz; ii) 120 h (B370/1), 260 h (B370/2), 360 h (B370/3) at low intensity and low frequency, 370 kHz; iii) 120 h (RF/1), 260 h (RF/2), 360 h (RF/3) at very low intensity and ultra high frequency, 900 MHz. Furthermore, another group of seeds was treated by laser beams of 248 nm wavelength whose magnetic field is coupled to an electric field. These two fields, by the Planck theory, origin the quantum energy, expresses by photons. Therefore, in the laser-matter interaction photons are absorbed dependent on laser shots. Again, we performed experiments at three duration time values that applied: 30 kshots (KrF/1), 80 kshots (KrF/2) and 135 kshots (KrF/3) at 40 mJcm2/ fluence. The magnetic field and electric field presented by the laser beam are approximatively 250 kVm/ and 850 µT, respectively. All treatments were performed at room temperature. Both untreated seeds and each group of seeds exposed to the physical stresses were transferred in Petri dishes and followed for their germination and seedling growth up to 96 h. The results showed that all physical stresses induced by alternate magnetic fields, radiofrequency and laser radiations did not have effect on seed germination as well as on cell elongation growth of the radish hypocotyls in comparison to control seeds. On the contrary, all physical stresses showed a significate stimulation on root growth.

本研究探究了施加于萝卜（Raphanus sativum L.）种子的可变磁场对种子萌发与幼苗生长的影响效应。本实验共测试了三种不同的交变磁场：其一为极低频（0.2 Hz）、高强度（40 mT）的磁场（记为B0.2）；其二为低频（370 kHz）、低强度（577 μT）的磁场（记为B370）；其三为超高频（900 MHz）、极低强度（约250 nT）的磁场（记为RF900）。第三种磁场所产生的电磁波，目前广泛应用于移动通信领域。
将一批批性状均一的萝卜种子分别置于上述三类交变磁场中进行处理，并设置三种不同的辐照时长：① 针对极低频0.2 Hz、高强度磁场：分别处理120 h（记为B0.2/1）、260 h（B0.2/2）及360 h（B0.2/3）；② 针对低频370 kHz、低强度磁场：分别处理120 h（B370/1）、260 h（B370/2）及360 h（B370/3）；③ 针对超高频900 MHz、极低强度磁场：分别处理120 h（RF/1）、260 h（RF/2）及360 h（RF/3）。
此外，另有一组种子采用波长为248 nm的激光束进行处理：该激光束同时伴随磁场与电场的耦合作用。根据普朗克理论，这两类场可产生由光子表征的量子能量。因此，在激光与物质相互作用的过程中，光子的吸收量取决于激光辐照次数。本实验同样设置三种不同的辐照时长（以激光脉冲数计）：在辐照通量为40 mJ/cm²的条件下，分别辐照30千次（记为KrF/1）、80千次（KrF/2）及135千次（KrF/3）。该激光束所伴随的磁场与电场强度分别约为250 kV/m及850 μT。所有处理均在室温条件下开展。
将未经过任何处理的对照组种子与所有经物理胁迫处理的实验组种子，均转移至培养皿中进行培养，并持续观测其萌发与幼苗生长情况至96小时。实验结果表明：与对照组种子相比，交变磁场、射频辐射及激光辐照所诱导的各类物理胁迫，均未对萝卜种子的萌发以及下胚轴细胞伸长生长产生显著影响。与之相反，上述所有物理胁迫均对萝卜幼苗的根系生长产生了显著的促进作用。