Eficiência do uso da radiação solar por plantas <i>Ilex paraguariensis</i> A. St. Hil. cultivadas sob sombreamento e a pleno sol

Abstract

RESUMOA eficiência de conversão da radiação solar em fitomassa é uma variável frequentemente utilizada em modelos de simulação do crescimento das culturas, pois a produção de biomassa está relacionada com a eficiência com que uma planta converte energia radiante em química, dada pelo processo da fotossíntese. Dessa maneira, o objetivo deste trabalho foi determinar a eficiência de conversão da radiação solar fotossinteticamente ativa interceptada (RFAi) em fitomassa aérea de Ilex paraguariensis, cultivada em consórcio (Ilex paraguariensis A. St. Hil. e Pinus elliottii Engelm) e solteira. Para tanto, foram determinados a radiação solar fotossinteticamente ativa interceptada (RFAi), o índice de área foliar e a fitomassa seca das erveiras sob sombreamento e a pleno sol, sendo então, a eficiência de conversão da RFAi em fitomassa seca produzida calculada por meio da relação entre a produção de fitomassa acumulada e a RFAi envolvida. Para um mesmo valor de radiação RFAi, obteve-se maior eficiência de uso da radiação no acúmulo em matéria seca aérea de Ilex paraguariensis cultivada em consórcio. A eficiência de conversão (εb) de fitomassa seca aérea de plantas de Ilex paraguariensis em relação à quantidade de radiação solar fotossinteticamente ativa interceptada acumulada foi de 0,83 g MJ -1 no sistema consórcio e de 0,23 g MJ -1 no sistema solteiro. Apesar disso, a produção de fitomassa aérea por planta de erva-mate foi maior no sistema solteiro. Palavras-chave: fitomassa; eficiência fotossintética; consórcio. ABSTRACTThe efficiency of conversion of the solar radiation in biomass is a variable frequently used in models of simulation the culture growth, because the biomass production is related with the efficiency of which a plant converts radiant energy in chemistry, given by the process of the photosynthesis. The objective of this work was to determine the efficiency of conversion of the photosynthetically active and intercepted solar radiation (RFAi) in Ilex paraguariensis biomass, cultivated in consortium (Ilex paraguariensis A. St. Hil. e Pinus elliottii Engelm) and single. For so much, it was determined the photosynthetically active and intercepted solar radiation (RFAi), the index of leaf area and the biomass dries of the seedlings, being then, the efficiency of conversion of RFAi in biomass dries of the cultivated in consortium and single. For a same radiation value RFAi, is obtained larger efficiency of use of the radiation in the accumulation in matter dries

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

“…With the higher seedling density in the trays, the accumulated TDM presented an increase in values, according to Ataíde et al (2010) and Caron et al (2014). The major accumulation of dry matter, obtained as a function of days after emergence in the treatment of high density, is associated to LAI.…”

“…Thus, the intercepted photosynthetically active radiation (PARi) that is converted into biomass, reveals the efficiency of the use of radiation (εb) by species (Monteith, 1977). In most cases, this process presents a linear function, as observed in the works developed by Stape et al (2008); Campoe et al (2013);Caron et al (2014), among others. One of the factors that is known to influence the εb is the leaf area index (LAI), a characteristic that can be modified by the density of seedlings.…”

“…The efficiency of interception of photosynthetically active radiation is directly related to the LAI, being that this factor influences the amount, duration of leaf area, and production potential of dry matter (Mayers et al, 1991). The increase in LAI results in higher levels of intercepted solar radiation (Caron et al, 2014).…”

Effects of growth reducer and nitrogen fertilization on morphological variables, SPAD index, interception of radiation and productivity of wheat

“…This result can be supplemented by Caron et al (2013), who found this behavior in the yerba mate associated with Pinus elliottii, and also by Sinclair et al (1992), who observed, for corn and soybean, that the increased diffuse radiation fraction resulted in more efficient use of radiation by the crops. This behavior may have been responsible for the significant difference among treatments with and without the application of the growth reducer, from dose of 120 kg ha -1 of N.…”

INDIRECT AND EXPEDITE ASSESSMENT OF Ilex paraguariensis COMMERCIAL YIELD

“…Considering the several aspects related to the improvement of the species, the effect of nutritional status of different provenances (OLIVA et al, 2014) and their respective progenies (STURION; RESENDE, 2005;RAKOCEVIC et al, 2005), the sexual dimorphism (male and female plants, (RAKOCEVIC et al, 2011;RESENDE, 2010), the cultivation system (in consortium or homogenous) (CARON et al, 2014) and the cultivation type have showed a strong influence on leaf mass production (RAKOCEVIC et al, 2007;2009). In a similar way, some morphological variations, mainly related to leaves (BASTOS et al, 2014;BORILLE et al, 2005;VALDUGA et al, 2016) were described in Brazil (REISSMANN et al, 2003) and Argentina (JANSSENS;SCHERER, 2011), however, they were not still linked to the productivity of the species.…”