Data/hora: 01/06/2024 15:04:32

Biblioteca(s): 	Epagri-Sede.	
Data corrente: 	09/12/2021	
Data da última atualização: 	09/12/2021	
Autoria: 	BALDISSERA, T. C.; PINTO, C. E.; GARAGORRY, F. C.; RECH, Â. F.; WERNER, S. S.; COSTA, M. D.	
Título: 	Canopy and leaf traits of Axonopus catharinensis Valls. submitted at nitrogen and shade levels.	
Ano de publicação: 	2021	
Fonte/Imprenta: 	In: REUNIÃO DA SOCIEDADE BRASILEIRA DE ZOOTECNIA, 56., 2021, Florianópolis . Resumos... Brasília: Sociedade Brasileira de Zootecnia, 2021. p. 33	
Idioma: 	Inglês	
Conteúdo: 	Axonopus catharinensis is a native species from Santa Catarina state, presents a high tolerance to shade and
have been adopted frequently in silvopatoral systems in southern Brazil. However, is not clear, how shade can
impact on canopy and leaf attributes of this species and if nitrogen can compensate for any trait reduction due
to shade. The objective was to evaluate different shade conditions and nitrogen doses in canopy and leaf traits
of A. catharinensis. The experiment was conducted in a completely randomized block design with four
replications at Epagri from January to June 2020. Treatments consisted of light conditions (full sun, 30 and 50%
of shade) and nitrogen doses (0, 50, 100, 150 and 300 kg ha-1). Shade conditions was created using wood slats
and checked during the day using a ceptomer (Decagon AccuPAR LP-80). In January 2019, micro canopies of
A. catharinensis were established in 45 experimental units (wooden boxes of 0.3m width x 1.0m length x 0.5m
depth) and remained until the end of the experiment. These wooden boxes were filled with sand and vermiculite
substrate 1:1 (v/v), irrigated with total nutrient solution, except for nitrogen. The experiment started in january
2020 when the micro canopies where standardized to 10cm heigth and nitrogen doses applied in urea form.
Every 1-2 weeks, a 0,25 m2 area was mowed at ground level, totaling five cuts for all treatments. It was evaluated
the leaf area index (LAI), specific leaf area (SLA) and tiller density (TD). Variance analysis and Tukey test was
performed using R environment. The LAI response was significant only for nitrogen doses (p<0,001). The LAI
at doses 300, 150 and 100 kg ha-1 were similar, where LAI at dose 300 was 4.2 and for dose 0 it was 1.3. SLA
was similar in all conditions (p>0,05). The TD had shade and nitrogen effect. In the shade conditions, TD values
were 947a, 882ab and 755b, for full sun, 30% and 50% shade levels, respectively. For nitrogen, TD followed a
similar pattern from LAI responses, where doses 300, 150 and 100 were similar. Furthermore, TD was almost
three times higher in dose 300 (1135 tillers m2) than the dose 0 (458 tillers m2). In general, plants growing in
reduced light condition alter their leaf shape and area to capture more light, enhancing LAI and SLA. This was
not observed in A. catharinensis, however there was a reduction in tiller density, a quite common response
pattern of shaded plants. In this way, to maintain similar levels of LAI, with lower number of tillers, probably, A.
catharinensis produced more leaves per tiller and/or presented leaves wider and longer. Nitrogen showed to be
extremely important to A. catharinensis, regardless of the light condition and doses equal or superior to 100 kg
ha-1 are required to A. catharinensis produce canopies with adequate structures. More evidence and new studies
are needed to conclude whether and how these results can impact on pasture production in restricted light
conditions.	
Palavras-Chave: 	integrated crop-livestock systems; plant nutrition; plant production and development; shade avoidance syndrome; silvopastoral systems.	
Categoria do assunto: 	F Plantas e Produtos de Origem Vegetal	
URL: 	http://intranetdoc.epagri.sc.gov.br/producao_tecnico_cientifica/DOC_50465.pdf	
Registro original: 	Epagri-Sede (Epagri-Sede)	
Exemplares: 	Epagri-Sede - (106539-1) - UPC - PL - DD -  -  -  - DIS