Abstract:

The differences of virus-free potato’s plant leaf growth，photosynthesis，chlorophyll fluorescence and tuberization in different light qualities were studied. Taking white light as control，the red light，red + blue light generated by light-emitting-diode were applied to study the influences of different LED light qualities such as white，red，blue，red/blue（7︰1）and red/blue（5︰1）on favorite virus-free potato plantlet. It showed that，under different light qualities，there were differences in photosynthesis and tuberization：the red/blue（5︰1）treatment resulted in better leaf area index，chlorophyll content，stomatal density，C_i，q_P，T_r and Φ_PSIIcompared with white light treatment；remarkably-improved P_n，G_sand ETR；earliest tuberization compared with white light treatment. However，the contents of chlorophyll decreased，P_n and Φ_PSII remarkably-decreased on the 60th day. It matured ahead of time with lower stolon. The micro-tuber yield and tuberization rate are the highest. Red light treatment resulted in decreased leaf area index，chlorophyll content，G_s，P_n，F_v/F_o，Φ_PSII and q_P，increased NPQ，slow-down tuber formation and lowest final yield. Furthermore，the blue light treatment was inhibit the formation of stolon and the limit the number of micro-tuber per plant. The analysis indicated that higher red light proportion in light quality can promote the formation of stolon while higher blue light proportion can promote the tuber formation and expansion，shorten the production cycle. Basing on the results，it is advisable to increase the red light proportion in the earlier stage of light adjustment to induce the formation of stolon，and to increase the blue light proportion in the late period to promote the tuber formation and expansion，increase the number and yield of tuber.

Key words: virus-free potato, micro-tuber, hydroponic culture, LED light quality, photosynthesis, chlorophyll fluorescence, tuberization