Seedling emergence of five varieties of citric rootstocks grown in environments with different levels of shading

Abstract

The emergence of citrus seedlings is influenced by several factors. One is the degree of brightness. The objective of the experiment was to evaluate the influence of four environments in the emergence of seedlings of five citrus varieties rootstocks. The work was carried out on private property located in the city of Alegre-ES, located at 20° 49' south latitude and 41° 32' west longitude and 322 m altitude. The experimental design was completely randomized in a split plot, with four rooms consisting of 0, 30, 50 and 80% shading in the plot and five varieties of rootstocks subplots, with four repetitions and twenty-five seeds per replicate. The rootstocks used were the Rangpur lime, lemon Volkameriano, Poncirus trifoliata, 'Swingle' citrumelo and Flying Dragon. After 60 days of sowing, emergence rate index, emergence percentage, leaf number and height were evaluated. At 124 days, leaf area, total chlorophyll (a + b), root dry mass and shoot were evaluated. The citric rootstocks tested responded differently when subjected to shading, and can use physiological and morphological mechanisms to maintain or even improve the emergence and seedling vigor. It was observed that the P. trifoliata rootstock obtained better performance when compared to others and that 50% shading can be adopted in this stage of citrus seedling production since it reduces seedling time in the tubes and does not affect the seedling quality.

Vermiculite and shading in the formation of 'Rangpur' lime rootstock

“…Regarding the emergence speed index (ESI), the seeds kept in full sun showed a higher value in a shorter time (12 DAE), while the seeds kept under medium and high shading showed a lower ESI and a later peak of this value, which occurred at 17 DAE (Figure 2B). These results differed from those in the study conducted by Marçal et al (2014), who obtained higher emergence rates and ESI in 'Cleopatra' mandarin seeds maintained under shading levels of 55.82 and 51.97%, respectively. Martins et al (2014) concluded that shadows of 30 and 50% favored an increase in the percentage of emergence of citrus rootstocks.…”

“…These results differed from those in the study conducted by Marçal et al (2014), who obtained higher emergence rates and ESI in 'Cleopatra' mandarin seeds maintained under shading levels of 55.82 and 51.97%, respectively. Martins et al (2014) concluded that shadows of 30 and 50% favored an increase in the percentage of emergence of citrus rootstocks.…”

“…There (Freitas et al, 2015). However, Martins et al (2014) found no differences for the SDM of 'Rangpur' lime seedlings grown under different light intensities, while greater root, shoot, and total dry matter accumulations were obtained in citrus rootstocks grown with a nutrientrich commercial substrate (Fochesato et al, 2006).…”

“…Light intensity has a direct effect on seed germination, emergence, growth, and survival as well as on seedling formation (Martins et al, 2014). Shade nets are an alternative to reduce the thermal amplitude and total solar radiation on plants, resulting in increased production in some species, among them fruit trees (Silva et al, 2020).…”

Shading as a means of mitigating water deficit in seedlings of Campomanesia xanthocarpa (Mart.) O. Berg

“…xanthocarpa occurs, it can be inferred that leaf expansion is facilitated by increased shading (Alvarenga et al, 2003;Martins et al, 2014). We observed hypotheses in the literature justifying the behavior of plants in the face of stressful conditions, such as the facilitation hypothesis, which suggests that shading minimizes water deficit, especially among species tolerant to drought and shade.…”