Extended Abstract
1. Introduction: The potato (Solanum tuberosum L.) is among the top five crops globally, serving as a primary food source for over one billion people worldwide. However, utilizing vegetative propagation with whole or cut tubers introduces various contaminations, resulting in reduced yields and quality. On the other hand, the large tubers produced through this method often need to be divided into smaller pieces to achieve the ideal weight range of 50 to 60 grams. Besides the risk of spreading pathogens, cutting the tubers requires additional time, financial resources, and labor. Because potato tuber production is influenced by short daylight conditions, tuber formation primarily occurs towards the end of the year when daylight hours and light intensity decrease. By incorporating an aeroponic system with supplementary lighting that includes monochromatic or a mix of essential light spectrums in different proportions, viable and effective methods are available for producing micro-tubers or improving their quality. Therefore, this ongoing study aims to assess how various LED light spectrums impact both the quantity and quality of Agria cultivar potato minitubers..
2. Materials and methods: To assess the impact of various supplemental lights on the yield and quality of minitubers from the Agria cultivar, an experiment was carried out using a completely randomized design with three replications. In vitro potato seedlings were prepared and then planted in an aeroponic system. LED lamps emitting different combinations of red (R), blue (B), white (W), and far-red (Fr) light were used either individually or in combination with other spectra. The study involved eight different treatment levels: T1 (100R), T2 (100R+Fr), T3 (75R:25B), T4 (75R:25B+Fr), T5 (50R:50B), T6 (50R:50B+Fr), T7 (W), T8 (W+Fr), and natural greenhouse light was used as the control treatment ( T9). The light intensity utilized was 100 μmol m^-2 s^-1, with far-red light making up 10% of the total supplemental light in treatments where it was applied.
3. Results and Discussion: The study's findings demonstrate the significant impact of different light spectrums on various characteristics of potato minitubers. These characteristics include the number and weight of minitubers, dormancy duration, sprouting minituber count and diameter, as well as dry matter content and firmness. Using all light spectrums increased both the quantity and weight of minituber yield, with treatments T1 and T7 showing the most significant improvements... Incorporating far-red light as supplemental lighting proved effective compared to the control, although it did not enhance the minituber quality indicators and may have had some adverse effect. The supplementary light also prolonged minituber dormancy compared to the control, but adjusting the blue to red light ratio showed promise in reducing dormancy. The highest firmness levels were observed in the white light treatment (T7), while the control treatment had the lowest firmness. Applying supplementary light negatively affected the dry matter content of the minitubers. The control treatment showed the highest dry matter content at 17.5%, while the T7 treatment had the lowest content. The use of supplemental lighting resulted in a decrease in the number of active sprouting minitubers. The control group had the highest number of active sprouting minitubers, with a total of two, while the T7 treatment had the lowest, with only one active sprouting minituber. Despite a general reduction in sprout diameter due to the supplemental light, the T5 treatment recorded the largest sprout diameter at 4.84 mm.
4. Conclusion: The findings of the study demonstrated that the use of various supplementary light spectra increased both the number and weight of minitubers per plant. Furthermore, this method prolonged the dormancy period of the minitubers and enhanced the firmness of the microtubers in all light treatments compared to the control group. In summary, the research suggests that the application of supplementary light, specifically white light excluding far-red light or 100% red light without far-red light, can yield positive outcomes in terms of minituber quantity, performance, and firmness. However, addressing the issue of extended dormancy before planting is crucial. It is advisable to either eliminate or reduce the far-red spectrum in supplemental lighting to less than 5%.