Physiological Parameters of Potato Explants as Affected by Silicon Nanoparticles under Drought Stress

Potential of growth and microtubrization of four potato cultivars (Hermes, Charlotte, Inova and Maris Peer) treated with two concentrations of Si-NPs (200 and 400 ppm) exposed to drought stress, induced by polyethylene glycol (PEG 10%) were studied. In general, Si-NPs at both concentrations enhanced most vegetative parameters of potato explants compared to PEG-stressed ones. Maximum stem length (16.9 cm), both number of leaves (18)and nods (20)/explant were recorded in 200 ppm of Si-NPs treated explants of Inova cv. with synthesizing of the highest number of protein bands in microtuber (11) separated by SDS-PAGE and maximum width of sieve elements (6µm) of phloem tissue examined by TEM. Also, low concentration of Si-NPs treated Hermes cv. explants gave the highest values of FW of explant (0.76g), minimum period for microtuber initiation (71d), maximum number (2.3) and FW (2.3g) of microtuber/explant which attributed with the highest number of separated protein bands in shoots (11). Si-NPs at high concentration (400ppm) gave the maximum thickness of 5 layers of phelloderm (275 µm) under phellem with large and abundant starch grains and maximum length of both sieve element (10µm) and companion cells (9 µm) of phloem.  It can recommend that, production of Si-NPs treated microtubers, under drought stress could be tolerant to drought and it must be evaluated under field conditions.