The high density of plants increases the radiation use efficiency of photosynthetically active seedlings of Japanese grape (Hovenia dulcis)

Abstract

The objective of this study was to determine the use efficiency intercepted photosynthetically active solar radiation of Hovenia dulcis seedlings grown under different plant density treatments. The experiment was conducted in a greenhouse at the forestry nursery. A complete randomized block design was applied. The study was characterized by two plant densities; high (494 plants m -2 ) and medium (247 plants m -2 ) densities of seedling in the trays, and fifteen evaluation periods that began after first emergence. Evaluations were carried out every 15 days, totaling 210 days, with six replications. The leaf area index, total dry biomass of seedlings, partitioning of dry biomass, interception of global radiation, accumulated intercepted photosynthetically active radiation, and use efficiency of radiation were evaluated. The high density treatments promoted greater use efficiency and accumulation of intercepted photosynthetically active radiation in dry biomass of Hovenia dulcis seedlings. In this work, a model is present for analyzing the growth and development of plants and their relation to both photosynthetic rate and radiation use efficiency.

MORFOLOGIA OVARIANA E DOS OVIDUTOS DE Trachemys scripta elegans (WIED, 1839, TESTUDINES) CRIADAS NO CERRADO BRASILEIRO

“…The efficiency of the use of radiation by plants depends on the interaction between vegetation and the environment, which defines how processes of photosynthesis and transpiration will be affected by climatic and edaphic elements or also how the structure of the canopy affects the amount of incident radiation that reaches the different layers of the same and its absorption by plants (Fonseca et al, 2006). Like this, by raising seedling density, the biomass accumulated by seedlings also increased, according to Schwerz et al (2017). Thus, the arrangement of plants can be considered an important management practice to control the interception of radiation.…”

“…Thus, εb can be calculated by means of the relation between the accumulated biomass production and the PARint. All calculations for obtaining εb were performed as shown by Behling et al (2015) and Schwerz et al (2017).…”

“…Guajuvira is indicated for civil construction, due to its characteristics of the wood, as well as for the recovery of degraded areas, since it presents good adaptability to shallow soils and low fertility. In the last decades the production of seedlings has been carried out in a protected environment, this physical environment many changes in the meteorological elements (Trautenmüller et al, 2016) and solar radiation is one of the most modified elements (Behling et al, 2015;Dalmolin et al, 2015;Schwerz et al, 2017), being considered a primordial element so that the seedlings develop of robust form. Plant growth is a ratio of biomass balance accumulated by photosynthesis, crop yield depends on the rates of photosynthesis in any growing environment (ORT & LONG, 2003;PTASINSKI, 2016;TAIZ et al, 2017).…”

“…Thus, the PARint, which is converted into biomass, reveals the conversion efficiency (EB) of the energy use by the species (Monteith, 1977). Most of the time, this conversion has been calculated by the linear function, in which an angulation between the PARint an accumulated biomass determines an EB, as results in the studies developed by Behling et al (2015) and Schwerz et al (2017).…”

“…The leaf area index can also influence εb, this characteristic can be manipulated through the density of plants (Behling et al, 2015). Thus, spacing inquiries have been conducted in order to shorten the period for the crop to intercept the maximum incident solar radiation per unit area and time, resulting in higher productivity (Schwerz et al, 2017).…”