Energy Efficient Lighting in Plant Factories: Addressing Utilance

Vertical farming is considered to play a crucial role in future food supply. Until today, the high amount of electrical energy required for artificial lighting has been problematic in this context. Various possibilities for increasing efficiency through adapted lighting conditions have been and are being investigated. However, comparably little attention is paid to increasing utilance, i.e., the amount of photons that can effectively be used by the plant. In this work, a novel targeted lighting strategy is therefore proposed that allows for a dynamic adaptation of the luminaires’ light distribution to match the effective crop size at each stage of plant growth in a fully-automated manner. It is shown that the resulting utilance can significantly be increased compared to standard full-coverage lighting. Moreover, it is found that the proposed strategy is likely to consume less than half of the electrical energy usually required for the latter. An additional increase in system efficiency can be prognosticated and the potential energy savings are estimated based on assumptions of future LED generations derived from literature.

Acorn Crop, Seed Size and Chemical Defenses Determine the Performance of Specialized Insect Predators and Reproductive Output in a Mediterranean Oak

Seed predation is an antagonistic interaction that negatively affects the performance of individual plants and can limit plant population dynamics. In animal-dispersed plants, crop size is an important determinant of plant reproductive success through its effect on seed dispersers and predators. Seed traits, such as size or chemical composition, can also increase the tolerance to seed predators or reduce their performance. We investigated the interaction between Quercus faginea and two specialized pre-dispersal insect seed predators (weevils and moths) during two years of contrasting crop size to determine the consequences of oak reproductive investment on seed production and insect performance. Crop size was 44% lower and acorns were 32% smaller in the second year, although acorn predation by insects was proportionally similar between both years at the population level. Individual trees producing larger crops showed a lower incidence of insect predators during the year of abundant acorn production, whereas trees producing bigger acorns experienced higher seed predation rates by insects, and acorns held more insect larvae in the low crop year. Competition between insects increased when acorn production was low, and higher tannin content in acorns further constrained the number of weevil larvae developing together in the same acorn. However, the abundance and size of insect larvae produced per tree were similar between the two crop years, and this was due to larvae often depleting acorn reserves when resources were low. Oak reproductive output increased nearly two-fold during the large crop year. Crop size variation, acorn production in a given year and acorn size and chemical composition seem to be important traits for reducing damage by insect predators in Quercus faginea and improve oak reproductive success.

Individual crop size increases predispersal predation by beetles in a tropical palm

Predispersal seed predation is one of the main causes of seed mortality in plant populations, contributing to decreased plant recruitment. Seed loss has previously been found to be related to crop size. Thus, we examined the influence of individual crop size on predispersal seed predation by beetles in the palm Syagrus flexuosa in the Brazilian savanna. The study was carried out in three tropical woodland savanna sites, where we sampled the total seed crop of 46 fruiting palms and checked the presence of beetle larvae inside all seeds per plant. We observed predispersal seed predation of S. flexuosa from all sites and a high variation in the number of seeds preyed on per individual palm. Crop size had a positive influence on the number of seeds lost to predispersal seed predators. Variations in levels of predispersal seed predation may also be accounted for by the reproductive phenology of S. flexuosa. If fruits are not available at the same time, less resource is available for predators and therefore a high proportion of seeds may be preyed on. Thus, our study demonstrates that an individual plant trait, crop size, is an important predictor of beetle seed damage per palm and a driver of the number of seeds lost to predispersal seed predators.

Intrinsic and extrinsic drivers of intraspecific variation in seed dispersal are diverse and pervasive

There is growing realization that intraspecific variation in seed dispersal can have important ecological and evolutionary consequences. However, we do not have a good understanding of the drivers or causes of intraspecific variation in dispersal, how strong an effect these drivers have, and how widespread they are across dispersal modes. As a first step to developing a better understanding, we present a broad, but not exhaustive, review of what is known about the drivers of intraspecific variation in seed dispersal, and what remains uncertain. We start by decomposing ‘drivers of intraspecific variation in seed dispersal’ into intrinsic drivers (i.e. variation in traits of individual plants) and extrinsic drivers (i.e. variation in ecological context). For intrinsic traits, we further decompose intraspecific variation into variation among individuals and variation of trait values within individuals. We then review our understanding of the major intrinsic and extrinsic drivers of intraspecific variation in seed dispersal, with an emphasis on variation among individuals. Crop size is the best-supported and best-understood intrinsic driver of variation across dispersal modes; overall, more seeds are dispersed as more seeds are produced, even in cases where per seed dispersal rates decline. Fruit/seed size is the second most widely studied intrinsic driver, and is also relevant to a broad range of seed dispersal modes. Remaining intrinsic drivers are poorly understood, and range from effects that are probably widespread, such as plant height, to drivers that are most likely sporadic, such as fruit or seed colour polymorphism. Primary extrinsic drivers of variation in seed dispersal include local environmental conditions and habitat structure. Finally, we present a selection of outstanding questions as a starting point to advance our understanding of individual variation in seed dispersal.

Comparison of two planting systems for several pear cultivars

Choice of orchard system is one of the major factors, on which pear crop size and quality depend. The purpose of this research was to assess the influence of two training systems involving trees trained to different number of leaders on growth, yield, and fruit quality of three pear cultivars. The study was conducted in 2001–2012 near Wrocław (south-western Poland). One-year-old trees of ‘Carola’, ‘Dicolor’ and ‘Erika’ cultivars on the Quince S1 rootstock were planted in the spring 2001 using 3.5 m between rows and a variable in-row spacing: 1.7 m (Drilling form with 3 leaders) and 1.2 m (Güttingen – V system with 1 leader). More vigorous growth was observed from more sparsely planted trees under the Drilling form. The total per-tree yield during 2002–2012 was decreasing as the planting density increased. No differences were observed on yield per hectare between the tested systems. The Drilling trees produced significantly heavier and larger fruit than the trees trained to the V-Güttingen system.

Training Systems for Cold Climate Interspecific Hybrid Grape Cultivars in Northern Climate Regions

Training systems influence grapevine (Vitis sp.) size, shape, and canopy architecture, which ultimately affects yield and fruit composition. Cold climate interspecific hybrid grapes (CCIHG) have propelled the creation of a new and fast-growing grape and wine industry in the northeast and upper midwest of the United States. This study evaluated the effect of three training systems: high cordon (HC), midwire vertical shoot positioning (VSP), and modified Scott Henry (SH) on vine growth, yield, and fruit composition of four CCIHG cultivars, Brianna, Frontenac, La Crescent, and Marquette, during two growing seasons. The divided canopy training system SH increased the crop yield per meter of row in all cultivars relative to HC and VSP, despite reduction in crop size imposed by crop thinning in vines trained to SH. VSP-trained vines had lower yields compared with HC, and this was most evident during the second year of the study, as vines were still being trained when the study commenced. Despite the higher crop size associated with vines trained in a SH system, there were minimal differences in fruit soluble solid concentration (SSC), titratable acidity (TA), and pH at harvest time. No differences were observed in vine size, expressed as dormant cane pruning weights, among training systems possibly because of the control of vegetative vigor, especially in VSP-trained vines, through shoot positioning and summer pruning. CCIHG cultivars appear to have the capacity to support higher yields under SH and HC systems without compromising fruit quality; however, labor requirements involved in establishing and maintaining more complex training systems should be considered when selecting a training system for CCIHG cultivars.