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​​​​Title: The legacy of summer pasture management on growth patterns in individual tillers and tillering of annual ryegrass (Lolium multiflorum L.) in the subsequent cold season

 

Abstract: The management of grazing height and the use of different doses of fertilization in summer pastures can modify processes related to the soil, growth and development of forages cultivated later, transferring a legacy to the subsequent culture in the cold season. Thus, it seems conceivable to propose that previous management of summer pasture (management heights and N doses) can change the dynamics of forage accumulation (growth and tillering) in the subsequent cold season of Lolium multiflorum L. For this purpose, the objective of this work was to determine whether summer management strategies employed in a biodiverse pasture composed of Cynodon spp., Pennisetum clandestinum, Trifolium repens L., Lotus corniculatus L. and Arachis pintoi alter the growth and tillering dynamics of the annual ryegrass in the cold season. The experiment was carried out at the Agroveterinary Science Center of the State University of Santa Catarina (CAV/UDESC). The experimental design used was randomized blocks with a 2 x 3 factorial arrangement, with three replications per treatment. The treatments used during the hot season (November to May) consisted of two management heights (17 and 23 cm) associated with three nitrogen rates (50, 150 and 250 kg of N ha-1 ). In the cold season (June to October), annual ryegrass pastures were managed at a height of 20 cm and received a single input of 50 kg of N ha-1 at the beginning of tillering. The dynamics of annual ryegrass tillering was quantified through the monthly count of emerged and surviving tillers in three rings of 0.01767m2 allocated in each experimental unit and from these, the tiller appearance, mortality and survival rates and the index of pasture stability. Tissue growth flux and senescence rate were quantified using the “tiller tiller” technique, in which 20 tillers were marked per experimental unit in order to obtain leaf appearance rate, leaf elongation and leaf life span. The results were submitted to analysis of variance using the MIXED procedure of the SAS® statistical package version 9.2, and the means of each variable were compared by Tukey's test with 5% probability. No legacy effect of summer pasture management was observed regarding the growth dynamics and tillering of annual ryegrass in the cold season, however, the half-life data reveal its relevance in the first generations considering them longer-lived and representing half of annual ryegrass production during the production cycle.

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Keywords: Biodiverse pasture. Legacy effect. Management height. Nitrogen.

 

Author: Francieli Piran

Leader: André Fischer Sbrissia

Dissertation (Masters in Animal Science)