In many parts of China, greenhouses are often not ventilated during winter and early spring to conserve heat. Hence, crops thus face unventilated conditions with the occlusion of air, resulting high humidity and low CO2 concentration. As is known, moderate air circulation plays an important role in regulating the micrometeorological environment around plants, and subsequently the growth is improved (Shibuya et al., 2006). Airflow movement improves the consistency of temperature, humidity, and CO2 in greenhouses (Kuroyanagi, 2016).
In a study on the influence of air disturbance on the variation of canopy temperature in a double-span greenhouse, Ishii et al. (2012) found that the sd of canopy temperature under air disturbance with air velocity of 0.5 m/s was less than 0.6 °C, and the sd of canopy temperature without air disturbance was more than 1.1 °C. Stagnant air will form a boundary layer on the surface of plants, and as a result, the physiological processes of crops are suppressed (Kuroyanagi, 2013; Kuroyanagi et al., 2013; Takayama et al., 2014). Appropriate air disturbance can regulate the microenvironment of plant canopy leaves, promote energy exchange between the crop canopy and the surrounding environment, reduce CO2 exchange resistance, increase CO2 concentration in the microenvironment of leaves, and improve the transpiration rate and promote photosynthesis (Elings et al., 2007). Shibuya et al. (2006) found that ventilation increased the exchange rate of CO2 inside and outside the canopy and increased the dry matter accumulation of tomato plants. In a solar greenhouse, Yang et al. (2007) found that the optimal air velocity in the flowering and fruiting stage of muskmelon was ≈1.0 m/s, which increased the leaf area index and stomatal conductance (gS) by 63.05% and 120.32%, respectively; the transpiration rate, photosynthetic rate, and fruit yield and quality were also significantly improved. A study performed in a single plastic greenhouse showed that the wetting time of the leaves is 1 h under ventilations and 5 h under no ventilation. Moreover, the reduction of the moisture condensation of leaves also inhibits the occurrence and spread of disease (Sekine et al., 2007).
A solar greenhouse is a common structure that is used for growing vegetable seedlings in northern China. To conserve heat in cold winter weather, the ventilation volume in these greenhouses is very small, and the airflow generated by the indoor temperature difference is extremely weak, so the indoor air is basically in a stagnant state (Bournet and Boulard, 2010; Kittas et al., 1996; Pérez-Parra et al., 2004; Wang et al., 1999). In addition, due to the use of the anti-insect netting, the airflow movement caused by natural ventilation inside and outside the facility in summer and autumn is greatly hindered (Fatnassi et al., 2002). At present, a horizontal fan is a type of air disturbance device that is widely used in greenhouses. Although turbulence fans can produce some air disturbance, the uniformity of air disturbance is insufficient, especially in solar greenhouses (smaller internal space). The coverage of the air velocity of 0.15 to 0.50 m/s at 1.5 m below the fan is only 73%, which results in poor uniformity of seedling growth (Zhang et al., 2016). Therefore, it is necessary to develop a controllable air disturbance device for growing seedlings in a solar greenhouse.
In this experiment, we designed an air blowing device that fastens to the seedbed and can move back and forth to provide accurate air velocity to the seedlings. This device was used to study the effect of airflow disturbance on the microenvironment of tomato seedlings during different seasons and its influence on seedling growth.
Bournet, P. & Boulard, T. 2010 Effect of ventilator configuration on the distributed climate of greenhouse: A review of experimental and CFD studies Comput. Electron. Agr. 74 2 1308 1314
Chaerle, L., Saibo, N. & Van Der Straeten, D. 2005 Tuning the pores: Towards engineering plants for improved water use efficiency Trends Biotechnol. 23 6 1308 1314
Downes, B.P., Steinbaker, C.R. & Crowell, D.N. 2001 Expression and processing of a hormonally regulated β-expansin from soybean Plant Physiol. 126 1 1308 1314
Fatnassi, H., Boulard, T., Demrati, H., Bouirden, L. & Sappe, G. 2002 Ventilation performance of a large Canarian-type greenhouse equipped with insect-proof nets Biosyst. Eng. 82 1 1308 1314
Franks, P.J. & Farquhar, G.D. 2007 The mechanical diversity of stomata and its significance in gas-exchange control Plant Physiol. 143 1 1308 1314
Greer, D.H. 2019 Modelling the seasonal changes in the gas exchange response to CO2 in relation to short-term leaf temperature changes in Vitis vinifera cv. Shiraz grapevines grown in outdoor conditions Plant Physiol. Biochem. 142 372 383
Huang, J.Y. & Lin, C.H. 2003 Cold water treatment promotes ethylene production and dwarfing in tomato seedlings Plant Physiol. Biochem. 41 3 1308 1314
Ishii, M., Limi, O., Moriyama, H. & Furihata, Y. 2012 Influence of circulation fans on the distribution of air temperature and air velocity in a greenhouse J. Sci. High Technol. Agr. 24 3 1308 1314
Joslin, J. & Henderson, G.S. 1984 Notes: The determination of percentages of living tissue in woody fine root samples using triphenyltetrazolium chloride For. Sci. 30 4 1308 1314
Kim, S.J., Hahn, E.J., Heo, J.W. & Paek, K.Y. 2004 Effects of LEDs on net photosynthetic rate, growth and leaf stomata of chrysanthemum plantlets in vitro Scientia Hort. 101 143 151
Kittas, C., Boulard, T., Mermier, M. & Papadakis, G. 1996 Wind induced air exchange rates in a greenhouse tunnel with continuous side openings J. Agr. Eng. Res. 65 1 1308 1314
Kuroyanagi, T., Yoshikoshi, H., Kinoshita, T. & Kawashima, H. 2013 Use of air circulation to reduce wet leaves under high humidity conditions Environ. Control Biol. 51 4 1308 1314
Moon, J.H., Kang, Y.K. & Suh, H.D. 2007 Effect of root-zone cooling on the growth and yield of cucumber at supraoptimal air temperature Acta Hort. 761 271 274
O’Shaughnessy, S.A. & Evett, S.R. 2010 Canopy temperature based system effectively schedules and controls center pivot irrigation of cotton Agr. Water Manage. 97 9 1308 1314
Sayed, O.H. 1996 Adaptational responses of Zygophyllum qatraense Hadidi to stress conditions in a desert environment J. Arid Environ. 32 4 1308 1314
Sekine, T., Aizawa, M., Nagano, T. & Takahashi, T. 2007 Suppression of gray mold and leaf mold of tomato by ventilation using fans and analysis of mechanism. Annual Rpt. Soc. Plant Production North Japan 58:46–53
Shibuya, T., Tsuruyama, J., Kitaya, Y. & Kiyota, M. 2006 Enhancement of photosynthesis and growth of tomato seedlings by forced ventilation within the canopy Scientia Hort. 109 3 1308 1314
Sun, Y.W., Chen, J.J., Chang, W.N., Tseng, M.J. & Wu, F.S. 2010 Irrigation with 5 °C water and paclobutrazol promotes strong seedling growth in tomato (Solanum lycopersicon) J. Hort. Sci. Biotechnol. 85 4 1308 1314
Tamasi, E., Stokes, A., Lasserre, B., Danjon, F., Berthier, S., Fourcaud, T. & Chiatante, D. 2005 Influence of wind loading on root system development and architecture in oak (Quercus robur L.) seedlings Trees 19 4 1308 1314
Takayama, K., Morimoto, C., Takahashi, H. & Nishina, H. 2014 Distributions of stem diameter and stem elongation rete in a large-scale tomato production greenhouse-measurement of a thousand plants Acta Hort. 1037 721 726
Wang, S., Boulard, T. & Haxaire, R. 1999 Air speed profiles in naturally ventilated greenhouse with a tomato crop Agr. For. Meteorol. 96 4 1308 1314
Wu, B.J., Chow, W.S., Liu, Y.J., Shi, L. & Jiang, C.D. 2014 Effects of stomatal development on stomatal conductance and on stomatal limitation of photosynthesis in syringa oblata and euonymus japonicus Thunb Plant Sci. 229 23 31
Yang, Z.C., Zou, Z.R., Wang, J., Chen, S.C. & Li, J.M. 2007 Effects of air speed in greenhouse on the growth of muskmelon plants Trans. Chinese Soc. Agricultural Eng. (Transactions of the CSAE) 23 3 1308 1314
Yamaguchi, S. & Kamiya, Y. 2000 Gibberellin biosynthesis: Its regulation by endogenous and environmental signals Plant Cell Physiol. 41 3 1308 1314
Zhang, Y., Feng, X.L., Zhao, S.M., Wang, W.R. & Ren, X.M. 2016 Effects of air circulator on environmental parameter and tomato growth in solar greenhouse China Vegetables 9 52 57
Zhang, R.D., Zhou, Y.F., Yue, Z.G., Chen, X.F., Gao, X., Ai, X.Y., Jiang, B. & Xing, Y.F. 2019a The leaf-air temperature difference reflects the variation in water status and photosynthesis of sorghum under waterlogged conditions PLoS One 14 7 E0219209
Zhang, L.L. & Zhang, S. 2019b The quantitative impact of different leaf temperature determination on computed values of stomatal conductance and internal CO2 concentrations Agr. For. Meteorol. 279 107700