Light altering film affects capsicum development and quality in a protected cropping facility

Protected cropping contributes significantly to food security, but it remains particularly sensitive to high energy costs associated with greenhouse environmental control. Smart Glass Film (SGF) was developed to reduce radiation in the heat-generating, but biologically irrelevant, wavelengths to reduce energy use and increase water and nutrient use efficiency. Light conditions in the greenhouse vary significantly on a seasonal basis, and thus may have impacts on production when crops are grown year-round. The study crop, capsicum (Capsicum annuum L.), is one of the most widely cultivated vegetables in the world and provides excellent nutrition and health benefits. Furthermore, light is one of the most important environmental factors regulating carbon gain, yield, fruit development, shelf life, and nutritional quality in capsicum. However, it is still unclear whether the impacts of SGF on light quantity and quality affect capsicum growth, yield and quality in the autumn and summer growing seasons in greenhouse conditions. In Chapter 1, I reviewed the impacts of advanced greenhouse cover materials, designed to reduce energy use by altering light transmittance, on leaf photosynthesis, physiology and yield of horticultural crops. In Chapter 2, two experiments were conducted in different seasons, autumn experiment (AE) and summer experiment (SE), on two genotypes of capsicum (Red and Orange) to assess the impacts of SGF on plant morphology, photosynthesis, and yield. In Chapter 3, two capsicum genotypes (Red and Orange) were harvested to examine the effects of SGF on fruit development, quality formation and shelf-life during the winter season in AE in a controlled environment greenhouse. In Chapter 4, transcriptome (RNA sequencing) experiments were conducted using 24 fruit samples collected from capsicum plants at 140~150 days after planting, combined with traits of detected components of carotenoids and cuticular thickness data (Chapter 3). In Chapter 5 (Summary), my PhD research examined the effects of SGF on the morphology of plant and fruit development, yield and nutrient accumulation, as a function of traits in capsicum, ranging from production to shelf-life assessment. This thesis provides useful insights into the links between advanced cover materials and capsicum physiology and molecular biology, which may guide future research for yield, postharvest quality, and engineering of new energy-saving cover materials