High Efficiency Cultivation Technology of Fruit Cucumber in Plant Factory

Plant factory, as the most advanced stage of the controlled environment, has drawn extensive concern in the world. In order to study high-yield vegetable varieties suitable for plant factory cultivation, we used fruit cucumber as an experimental material to study their high-yield cultivation technique in plant factory, and to clarify their planting management, cultivation cycle, yield and annual output. In our experimental condition, the average yield of the cucumber was about 2 500 g and their annual total yield per square meter could reach to 70 kg.

Two-stage seedling cultivation method for sweet peppers combining closed plant factory and solar greenhouse

This study introduced a two-stage cultivation method for sweet pepper seedlings, integrating the strengths of a closed plant factory and solar greenhouse, to mitigate the environmental constraints in Northeast China during the early spring season. In the first stage, seedlings were cultivated in a closed plant factory, followed by a second stage in a solar greenhouse. Four treatments- T1 (9 and 36 d), T2 (12 and 33 d), T3 (15 and 30 d), and T4 (18 and 27 d) - were designed for the first and second stages, respectively, with solar greenhouse-only approach serving as the control (CK). The findings reveal that the two-stage methodology significantly outperformed the control across multiple metrics, including seedling health index, chlorophyll content, photosynthetic capacity, yield, etc. Specifically, T3 emerged as optimal, boosting the health index by 38.59%, elevating chlorophyll content by 39.61%, increasing net photosynthesis by 34.61%, and augmenting yield per plant by 40.67%. Additionally, T3 expedited the time to harvest by 25 d compared to the control. Although the seedling cost for T3 was 0.12 RMB yuan higher, the benefits offset the additional investment. In conclusion, the two-stage cultivation method effectively leverages the advantages of both closed-plant factories and solar greenhouses, resulting in superior seedling quality compared to using only solar greenhouses. It offers a practical and economically viable solution for enhancing the quality and yield of sweet pepper seedlings, thus contributing to the progress in the field of facility seedling cultivation research.

Effects of environment lighting on the growth,photosynthesis,and quality of hydroponic lettuce in a plant factory

Leafy vegetable production under controlled environment using artificial lighting has many advantages over conventional greenhouses and open-field production.However,high initial investment and operation costs are restricting the wide application of this technology.In order to design an optimal artificial lighting environment for lettuce production,effects of different combinations of light intensity,photoperiod,and light quality on growth,quality,photosynthesis,and energy use efficiency of lettuce(Lactuca sativa L.cv Ziwei)were investigated under a closed plant factory.Lettuce transplants were grown under photosynthetic photon flux density(PPFD)at 150μmol/m^(2)·s,200μmol/m^(2)·s,250μmol/m^(2)·s,and 300μmol/m^(2)·s provided by fluorescent lamps(FL)with a red to blue ratio(R:B ratio)of 1.8 and light-emitting diode(LED)lamps with R:B ratio of 1.2 and 2.2,in combination with photoperiod of 12 and 16 h/d.In order to examine the“long term”photosynthetic characteristics,net photosynthetic rates of hydroponic lettuce leaves were continuously measured for 2 d(15^(th) and 16^(th) day after transplanting)before harvest.There was no difference in leaf fresh weight(FW)between PPFD of 250μmol/m^(2)·s and 300μmol/m^(2)·s with photoperiod of 16 h/d,regardless of light quality,and same results showed in contents of nitrate,soluble sugar,and vitamin C,respectively.The results of continuous measurements of net photosynthetic rate of lettuce leaves before harvest indicated that plants grown at PPFD of 250μmol/m^(2)·s had consistently higher compared to those grown at PPFD of 300μmol/m^(2)·s.Combining the results from growth,photosynthesis,quality,and energy consumption,it can be concluded that PPFD at 250μmol/m^(2)·s with photoperiod of 16 h/d under LED with R:B ratio of 2.2 is a suitable light environment for maximum growth and high quality of commercial lettuce(cv.Ziwei)production under indoor controlled environment.

Application status and challenges of machine vision in plant factory—A review

Plant factories have a great potential for mitigating the contradiction between the world’sgrowing population and food scarcity. During the process of its automatic production,machine vision plays a significant role. This technique almost covers every production linkfrom raising seedlings, transplanting, management, and harvesting to fruit grading. To provide references and a starting point for those who are committed to studying this issue. Inthis paper, the application prospects of machine vision in plant factories were analyzed,and the present researches were summarized from the fields of plant growth monitoring,robot operation assistance, and fruit grading. The results found that although the existingmethods have solved some practical problems at low cost, high efficiency and precision,some challenges still are faced by machine vision. Firstly, the changing lighting, complexbackgrounds, and color similarity within plant different parts cause the commonly usedimage segmentation algorithms to fail. The shortage of standard agricultural datasets alsokeeps deep learning and unsupervised classification algorithms from making progress.Secondly, there are some theoretical knowledge gaps for machine vision application in aparticular environment of plant factories, which seriously contains its application effect.Thirdly, the lack of special image acquisition devices and supporting facilities resulted inpoor image quality. All these factors hinder machine vision application in plant factories.Nevertheless, it is still a powerful tool and irreplaceable at present. We believed that thistechnique would promote plant factory development greatly with more robust, efficient,and reliable algorithms are developed in the future.

Modeling and simulation of temperature control system in plant factory using energy balance

Closed production systems,such as plant factories and vertical farms,have emerged to ensure a sustainable supply of fresh food,to cope with the increasing consumption of natural resource for the growing population.In a plant factory,a microclimate model is one of the direct control components of a whole system.In order to better realize the dynamic regulation for the microclimate model,energy-saving and consumption reduction,it is necessary to optimize the environmental parameters in the plant factory,and thereby to determine the influencing factors of atmosphere control systems.Therefore,this study aims to identify accurate microclimate models,and further to predict temperature change based on the experimental data,using the classification and regression trees(CART)algorithm.A random forest theory was used to represent the temperature control system.A mechanism model of the temperature control system was proposed to improve the performance of the plant factories.In terms of energy efficiency,the main influencing factors on temperature change in the plant factories were obtained,including the temperature and air volume flow of the temperature control device,as well as the internal relative humidity.The generalization error of the prediction model can reach 0.0907.The results demonstrated that the proposed model can present the quantitative relationship and prediction function.This study can provide a reference for the design of high-precision environmental control systems in plant factories.

摩天大厦型作物工厂——保障城市食物快速增长需求的作物高效生产系统

Vertical farming systems,such as sky farms,are a potential type of agricultural system for stable and effective food production.Here,we highlight the potential of the sky farm,denoted as the“skyscraper crop factory”(SCF),for cereal crop production and discuss some nascent technologies that would be applied in this production system.SCFs are ideal crop-production systems for increasing the effective arable area for crops and ensuring food security in times of crises that cause a shock in global trade.They can also provide food in urban areas to meet producers’and consumers’demands for the increased nutrition,taste,and safe production of cereal crops.Moreover,as their use can reduce greenhouse gas emissions,SCFs could be a sustainable addition to conventional agricultural crop production.

Effects of Variable Lighting Intensity on Growth Characteristics and Nutritional Quality of Hydroponically Grown Arugula(Eruca sativa Mill.)

Arugula(Eruca sativa Mill.),as an edible medicinal vegetable of peculiar flavor,is served as uncooked dish.The influence of variable lighting intensity(LI)on the growth characteristics and nutritional quality of hydroponically grown arugula was investigated by using light-emitting diodes(LEDs)to light the hydroponically grown arugula for a reference for industrialized arugula production.The dynamic demands of arugula for LI in the seedling stage,initial growth stage and vigorous growth stage were tested under two light quality conditions including a red/blue light ratio of 7:1 and a light/dark photoperiod of 12 h/12 h.Then,the curves of variable LI-induced changes in the growth indices of arugula in different development periods were drawn.Next,the influence of variable LI on the growth characteristics and nutritional quality of arugula was investigated by measuring the dry/fresh weight ratio,chlorophyll content,vitamin C content and soluble protein content.Variable LI significantly increased the height,stem diameter,leaf width,dry/fresh weight ratio,chlorophyll content and soluble protein content of arugula plant.Plant height,stem diameter,dry/fresh weight ratio,chlorophyll content and soluble protein content were the highest in the group exposed to LI of 200,300 and 300μmol•m^(-2)•s^(-1)during the seedling stage,initial growth stage and vigorous growth stage,respectively.The greatest leaf width was achieved at LI of 100,250 and 350μmol•m^(-2)•s^(-1),respectively.High intensity LI markedly repressed the synthesis of vitamin C.

Improvement of light uniformity by lighting arrangement for standardized crop production

In a commercialized, fully artificial plant factory, artificial luminaire is arranged in a unified way using a general illumination theory, an actual measurement, or an empirical methodology. However, with these methods, lightings are implemented without considering specific optical characteristics of lighting or material characteristics of each component that constructs a cultivation system, resulting in an amount of light that becomes irregular. The amount of lighting is closely related with the growth and quality of crops, and the deviation between points where cultivated crops are located causes quality difference in the produced crops, thus impairing the economic feasibility of a plant factory. In this regard, a simulation to figure out an optimum lighting layout was performed. Arrangements based on the spectrum distribution of light source and reflector materials were implemented to ascertain the distance between lighting and height of lighting and gather information in the pre-treatment process to improve the uniformity of light in the plant cultivation system. Improvement of around 15% in light uniformity is achieved compared with the existing system after the simulation is carried out. This result would reduce the deviation in crop growth to make uniform quality crop production possible.

Towards sustainable plant factories with artificial lighting (PFALs) for achieving SDGs

The challenges and opportunities for developing sustainable plant factories with artificial lighting(PFALs)are discussed.After examining the production cost and productivity of existing PFALs in Japan,the possibility of introducing a relatively new concept and methodology for considerably improving productivity are discussed in relation to environmental controllability and resource use efficiencies.The fundamental and potential characteristics of ideal or next-generation PFALs(n-PFALs)are then discussed with some suggestions for actualizing n-PFALs.Finally,perspectives of the n-PFALs and technologies to be integrated into the n-PFALs are presented in relation to the Sustainable Development Goals(SDGs)to be achieved by 2030.

Advances in greenhouse automation and controlled environment agriculture:A transition to plant factories and urban agriculture

Greenhouse cultivation has evolved from simple covered rows of open-fields crops to highly sophisticated controlled environment agriculture(CEA)facilities that projected the image of plant factories for urban agriculture.The advances and improvements in CEA have promoted the scientific solutions for the efficient production of plants in populated cities and multi-story buildings.Successful deployment of CEA for urban agriculture requires many components and subsystems,as well as the understanding of the external influencing factors that should be systematically considered and integrated.This review is an attempt to highlight some of the most recent advances in greenhouse technology and CEA in order to raise the awareness for technology transfer and adaptation,which is necessary for a successful transition to urban agriculture.This study reviewed several aspects of a high-tech CEA system including improvements in the frame and covering materials,environment perception and data sharing,and advanced microclimate control and energy optimization models.This research highlighted urban agriculture and its derivatives,including vertical farming,rooftop greenhouses and plant factories which are the extensions of CEA and have emerged as a response to the growing population,environmental degradation,and urbanization that are threatening food security.Finally,several opportunities and challenges have been identified in implementing the integrated CEA and vertical farming for urban agriculture.

Growth,nutritional quality,and energy use efficiency in two lettuce cultivars as influenced by white plus red versus red plus blue LEDs

Red plus blue light-emitting diodes(LEDs)are commonly applied in plant factories with artificial lighting due to photosynthetic pigments,which absorb strongly in red and blue light regions of the spectrum.However,plants grown under natural environment are used to utilizing broad-wide spectrum by long-term evolution.In order to examine the effects of addition light added in red plus blue LEDs or white LEDs,green and purple leaf lettuces(Lactuca sativa L.cv.Lvdie and Ziya)were hydroponically cultivated for 20 days under white LEDs,white plus red LEDs,red plus blue LEDs,and red plus blue LEDs supplemented with ultraviolet,green or far-red light,respectively.The results indicated that the addition of far-red light in red plus blue LEDs increased leaf fresh and dry weights of green leaf lettuce by 28%and 34%,respectively.Addition of ultraviolet light did not induce any differences in growth and energy use efficiency in both lettuce cultivars,while supplementing green light with red plus blue LEDs reduced the vitamin C content of green leaf lettuce by 44%and anthocyanin content of purple leaf lettuce by 30%compared with red plus blue LEDs,respectively.Spectral absorbencies of purple leaf lettuce grown under red plus blue LEDs supplemented with green light were lower in green light region compared with those grown under red plus blue LEDs,which was associated with anthocyanin contents.White plus red LEDs significantly increased leaf fresh and dry weights of purple leaf lettuce by 25%,and no significant differences were observed in vitamin C and nitrate contents compared with white LEDs.Fresh weight,light and electrical energy use efficiencies of hydroponic green and purple leaf lettuces grown under white plus red LEDs were higher or no significant differences compared with those grown under red plus blue LEDs.In conclusion,white plus red LEDs were suggested to substitute for red plus blue LEDs in hydroponic lettuce(cv.Lvdie and Ziya)production in plant factories with artificial lighting.