Determining the Relationship between Floral Initiation and Source–Sink Dynamics of Tomato Seedlings Affected by Changes in Shading and Nutrients

Abstract

<jats:p>Floral initiation is an important transition point from vegetative growth to reproductive growth in tomatoes and is known to be affected by light intensity, temperature, and nutrients. However, the regulation between flower formation and environmental factors, including nutrient conditions, due to source–sink dynamics (supply and demand of photoassimilates) is seldom documented. To evaluate the effects of light intensity and nutrition conditions on prefloral formation and development, dynamic floral characteristics during development were fitted with sigmoidal logistic curves under four light treatments with shading nets in two nutrient conditions. Source activity and sink strength were altered, which caused differences in the floral positions, length of floral shoots, floral initiation dates, and leaf numbers under the different treatments. Accumulated light acts upstream of nutrition supply during the formation of buds and leads to the accumulation of carbohydrates in source organs. Leaf area reached ≈500 cm<jats:sup>2</jats:sup>, and dry matter weights reached ≈3 g in each treatment until the flowering day, revealing that some level of photoassimilates are necessary for floral initiation. Both days to flowering and bud number were highly correlated with daily light integral (DLI) from 6 to 12 days before anthesis, which means this period is important for anthesis in tomato. Our results highlight regulation of the transition from vegetative growth to reproductive growth by tomato seedlings due to environmental factors and nutrients. A better understanding of communication between source organs and sink organs during floral initiation response to different environments is expected to provide management strategies for greenhouse tomato production.</jats:p>

Effect of Daily Light Integral on Cucumber Plug Seedlings in Artificial Light Plant Factory

“…The promotion of DLI to flower development is usually accompanied by an increased shoot biomass [23,28,34,43]. Leaf area reached 500 cm 2 , and dry mass reached 3 g, which were prerequisite for the flowering of tomato seedlings, revealing that some level of photoassimilates is necessary for floral initiation [23]. In this study, the decreased shoot biomass and leaf area with a higher DLI might have slowed down the development of cucumber seedlings, which stunted flower development after transplant.…”

“…As in Ji's [20] experiment, when DLI exceeded 14.4 mol•m −2 •d −1 , the correlation between the fresh mass and dry mass of the shoot in three cucumber seedlings and DLI changed from positive to negative. The promotion of DLI to flower development is usually accompanied by an increased shoot biomass [23,28,34,43]. Leaf area reached 500 cm 2 , and dry mass reached 3 g, which were prerequisite for the flowering of tomato seedlings, revealing that some level of photoassimilates is necessary for floral initiation [23].…”

“…Increases in DLI during the seedling stage have been also reported to accelerate subsequent floral initiation and decrease the time to the first flowering after transplant [13,21,22]. The number of tomato floral buds and days to flowering increased corresponding to the decrease in the shading before anthesis [23].…”

Distribución de fotoasimilados en los órganos vertederos de plantas Solanaceas, caso tomate y papa. Una revisión

“…Para el caso de los cultivares de tipo de crecimiento determinado durante la fase vegetativa los fotoasimilados se translocan para la formación y crecimiento de tallos, hojas y raíces, y posteriormente gran parte de esta se transfiere a las flores y frutos (vertederos) cuando inicia la fase reproductiva. En contraste, con los cultivares de tipo indeterminado, cuando se inicia la fase reproductiva, además de distribuir fotoasimilados en las flores y frutos, también se direccionan hacia las zonas vegetativas de crecimiento activo (meristemos apicales y laterales) lo cual, genera una competencia por la distribución de los fotoasimilados (Quintana-Baquero et al, 2010;Wang et al, 2020). Por ello es importante tener en cuenta la fuerza de los órganos fuentes (hojas maduras), definida como la capacidad de asimilar y convertir el CO 2 a azucares y posteriormente exportarlo (Rodrigues et al, 2019) y, por otro lado, la fuerza del vertedero, que es la capacidad para importar, utilizar León-Burgos et al, Distribución fuente/vertedero en Solanaceas y metabolizar los fotoasimilados (Bihmidine et al, 2013;Chang et al, 2017;Ji et al, 2020).…”

“…El proceso de distribución de fotoasimilados en las plantas requiere la formación y translocación continua de compuestos carbonados desde los órganos fuente; definidos como tejidos o órganos autótrofos fotosintéticos, generalmente hojas maduras o bien desarrolladas (Chang et al, 2017;Rodrigues et al, 2019), los cuales, producen carbohidratos para asignarlos a diferentes procesos esenciales en la planta como el crecimiento y desarrollo o translocar estos compuestos hacia los órganos vertederos como hojas en formación, tallos, raíces, flores y frutos (Castellanos et al, 2010;Bihmidine et al, 2013;Osorio et al, 2014;Aluko et al, 2021). Se ha estimado que alrededor del 80% de los fotoasimilados de las hojas son transportados hacia los órganos vertederos en forma de azúcares solubles, los cuales, proceden de la asimilación de CO 2 en las hojas (fotosíntesis) y de procesos de óxidoreducción (metabolismo de azúcar), para que finalmente se movilicen a través del floema hacia los órganos vertederos (Wang et al, 2020;Aluko et al, 2021;López-Delacalle et al, 2021). Sin embargo, este transporte puede ser afectado por condiciones de estrés abiótico y biótico o por el desbalance en la relación de órganos fuente/vertedero.…”