03837naa a2200241 a 450000100080000000500110000800800410001910000220006024501230008226000090020552029890021465300380320365300200324165300370326165300290329865300260332770000170335370000210337070000170339170000180340870000170342677301520344311315862021-12-09       2021    bl uuuu     u00u1 u    #d1 aBALDISSERA, T. C.  aCanopy and leaf traits of Axonopus catharinensis Valls. submitted at nitrogen and shade levels.h[electronic resource]  c2021  aAxonopus 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&lt0,001). 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&gt0,05). 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.  aintegrated crop-livestock systems  aplant nutrition  aplant production and development  ashade avoidance syndrome  asilvopastoral systems1 aPINTO, C. E.1 aGARAGORRY, F. C.1 aRECH, ??. F.1 aWERNER, S. S.1 aCOSTA, M. D.  tIn: REUNI??O DA SOCIEDADE BRASILEIRA DE ZOOTECNIA, 56., 2021, Florian??polis . Resumos... Bras??lia: Sociedade Brasileira de Zootecnia, 2021. p. 33