Continuous Light as a way to increase Greenhouse Tomato Production

Tomato plants need six hours of darkness per day for optimal growth; therefore, photosynthesis does not take place for 25% of the day. If tomatoes could be grown under continuous light, a substantial increase in production is expected. In practice, however, continuous light-grown tomato plants develop a potentially lethal mottled chlorosis. Such continuous-light-induced injury is only poorly understood so far. Recently, we proposed a number of hypotheses that aim to explain the continuous-light-induced injury, and rediscovered that wild-tomato species were reported as continuous-light-tolerant. Here, we (i) present a simulation study which shows that if an ideal continuous-light-tolerant tomato genotype is used and no crop adaptations to continuous light are assumed, greenhouse tomato production could be 26% higher when using supplementary lighting for 24 h day-1 in comparison with using supplementary lighting only for 18 h day-1 during day time, and (ii) discuss expected changes in greenhouse energy budgets and alterations in crop physiological responses that might arise from cultivating tomatoes under continuous light

Study of errors in the integration of the two-body problem using generalized Sundman's anomalies

[EN] As is well known, the numerical integration of the two body problem with constant step presents problems depending on the type of coordinates chosen. It is usual that errors in Runge-Lenz's vector cause an artificial and secular precession of the periaster although the form remains symplectic, theoretically, even when using symplectic methods. Provided that it is impossible to preserve the exact form and all the constants of the problem using a numerical method, a possible option is to make a change in the variable of integration, enabling the errors in the position of the periaster and in the speed in the apoaster to be minimized for any eccentricity value between 0 and 1. The present work considers this casuistry. We provide the errors in norm infinite, of different quantities such as the Energy, the module of the Angular Moment vector and the components of Runge-Lenz's vector, for a large enough number of orbital revolutions.Lopez Orti, JA.; Marco Castillo, FJ.; Martínez Uso, MJ. (2014). Study of errors in the integration of the two-body problem using generalized Sundman's anomalies. SEMA SIMAI Springer Series. 4:105-112. doi:10.1007/978-3-319-06953-1_11S1051124Brower, D., Clemence, G.M.: Celestial Mechanics. Academic, New York (1965)Brumberg, E.V.: Length of arc as independent argument for highly eccentric orbits. Celest. Mech. 53, 323–328 (1992)Fehlberg, E., Marsall, G.C.: Classical fifth, sixth, seventh and eighth Runge–Kutta formulas with stepsize control. Technical report, NASA, R-287 (1968)Ferrándiz, J.M., Ferrer, S., Sein-Echaluce, M.L.: Generalized elliptic anomalies. Celest. Mech. 40, 315–328 (1987)Gragg, W.B.: Repeated extrapolation to the limit in the numerical solution of ordinary differential equations. SIAM J. Numer. Anal. 2, 384–403 (1965)Janin, G.: Accurate computation of highly eccentric satellite orbits. Celest. Mech. 10, 451–467 (1974)Janin, G., Bond, V.R.: The elliptic anomaly. Technical memorandum, NASA, n. 58228 (1980)Levallois, J.J., Kovalevsky, J.: Géodésie Générale, vol. 4. Eyrolles, Paris (1971)López, J.A., Agost, V., Barreda, M.: A note on the use of the generalized Sundman transformations as temporal variables in celestial mechanics. Int. J. Comput. Math. 89, 433–442 (2012)López, J.A., Marco, F.J., Martínez, M.J.: A study about the integration of the elliptical orbital motion based on a special one-parametric family of anomalies. Abstr. Appl. Anal. 2014, ID 162060, 1–11 (2014)Nacozy, P.: The intermediate anomaly. Celest. Mech. 16, 309–313 (1977)Sundman, K.: Memoire sur le probleme des trois corps. Acta Math. 36, 105–179 (1912)Tisserand, F.F.: Traité de Mecanique Celeste. Gauthier-Villars, Paris (1896)Velez, C.E., Hilinski, S.: Time transformation and Cowell’s method. Celest. Mech. 17, 83–99 (1978

Plants under continuous light

Continuous light is an essential tool for understanding the plant circadian clock. Additionally, continuous light might increase greenhouse food production. However, using continuous light in research and practice has its challenges. For instance, most of the circadian clock-oriented experiments were performed under continuous light; consequently, interactions between the circadian clock and the light signaling pathway were overlooked. Furthermore, in some plant species continuous light induces severe injury, which is only poorly understood so far. In this review paper, we aim to combine the current knowledge with a modern conceptual framework. Modern genomic tools and rediscovered continuous light-tolerant tomato species (Solanum spp.) could boost the understanding of the physiology of plants under continuous ligh