ABSTRACT
It is already known that light quality and intensity have major influences on the growth, etiolation, germination, and morphology of many plant species, but there is limited information about the effect of wavelength and light intensity on nutrient absorption by plants. Therefore, this study was established to evaluate the plant growth, stomata formation, chlorophyll index, and absorption of macro- and micronutrients by common bean plants under six light treatments. The experimental design was completely randomized and consisted of six treatments: strong blue (blue LED at high light intensity); weak blue (blue LED at low light intensity); strong red (red LED at high light intensity); weak red (red LED at low light intensity; pink (combined red + blue LED), and white (combined red + white led). The stomatal density (stomata mm-2); the SPAD index; plant height (cm); root length (cm); plant dry weight (g); root dry weight (g); and the concentrations of N, S, K, Mg, Ca, B, Zn, Mn, and Fe on leaf analysis were influenced by all treatments. We found that plant photomorphogenesis is controlled not only by the wavelength, but also by the light intensity. Etiolation was observed in bean plants under blue light at low intensity, but when the same wavelength had more intensity, the etiolation did not happen, and the plant height was the same as plants under multichromatic lights (pink and white light). The smallest plants showed the largest roots, some of the highest chlorophyll contents, and some of the highest stomatal densities, and consequently, the highest dry weight, under white LED, showing that the multichromatic light at high intensity resulted in better conditions for the plants in carbon fixation. The effect of blue light on plant morphology is intensity-dependent. Plants under multichromatic light tend to have lower concentrations of N, K, Mg, and Cu in their leaves, but the final amount of these nutrients absorbed is higher because of the higher dry weight of these plants. Plants under blue light at high intensity tended to have lower concentrations of N, Cu, B, and Zn when compared to the same wavelength at low intensity, and their dry weight was not different from plants grown under pink light. New studies are needed to understand how and on what occasions intense blue light can replace red light in plant physiology.
ABSTRACT
Major changes are needed both with regard to what we eat and how food is produced. The latter is the focus of the present research, specifically the rise of controlled environment agriculture. In this context, empirical research is presented on consumer attitudes to vertical farming (VF) (i.e., indoor plant factory with artificial lighting), conducted in four countries (USA, UK, Singapore, and China) using online surveys (637-683 participants per country with matched gender and age group distributions). A multi-method research approach was used, including a novel methodology of text highlighting, which requires that participants read a descriptive text about VF with mentions of pros and cons and use highlighter functions to select aspects of the text that they 'like' and 'dislike'. Based on the information provided in the text, attitudes towards VF were largely positive in the four countries. The characteristics of VF that aligned with the United Nations Sustainable Development Goals were identified as key drivers of positive attitudes (i.e., higher yield, reduction of carbon emissions, and securing access to food). On the other hand, high energy use and premium prices contributed to negative attitudes about VF. Although the majority of participants responded to the text with an overall positive attitude towards VF, there were smaller groups of participants in every country who expressed a negative or neutral/ambivalent attitude. These between-segment differences were larger than cross-cultural differences, although the latter did exist, particularly for selected aspects of VF. For example, Chinese participants tended to be the least negative about the use of robots to help planting and harvesting. Future research is needed to understand consumer responses to aspects VF not covered in the text (e.g., powering VF with renewable energy, product range), and consumer insights about VF should be sought in other countries.