Open Access

ARTICLE

Defoliation management of kleingrass (Panicum coloratum L. var coloratum) cv Verde

by Ferri CM, VV Jouve, AM Sáenz

Universidad Nacional de La Pampa, Facultad de Agronomía, CC 300, L-6300, Santa Rosa, La Pampa, Argentina.

Address correspondence to: Dr. Carlos Ferri, TE/Fax +54 (02954) 451600; e-mail:

Phyton-International Journal of Experimental Botany 2017, 86(all), 190-198. https://doi.org/10.32604/phyton.2017.86.190

Abstract

The defoliation frequency determines above and below ground biomass accumulation, pasture structure and nutritive value. Two defoliation experiments with Panicum coloratum were performed, from September to March. One of them was conducted in pots under greenhouse conditions, and the other one in field plots for three growing seasons (EC) at the Faculty of Agronomy, La Pampa, Argentina (36˚ 46' S; 64˚ 16' W). Defoliation frequency treatments were four cutting intervals (IC; 3, 4, 6 and 8 weeks). In greenhouse experiment, live leaf blade accumulation rates (TAL), tiller appearance (TAM) and death (TMM) rates, live leaf blade length (LL) and above and below ground dry matter (MS) accumulation were determined. In field plots tiller height, weight and tiller, crude protein (PB) and dry matter accumulation were determined. TAL and the TAM were 1.28 (0.1024 vs 0.0798 cm/tiller/°Cd; P<0.01) and 1.92 (0.0133 vs 0.0069 tillers/°Cd; P<0.01) times higher in the IC3 and 4 vs 6 and 8 weeks, respectively. The TMM was 1.38 (0.0087 vs 0.0063 tillers/°Cd; P<0.01) times higher in the IC 8 vs 3, 4 and 6 weeks. Increased IC resulted in a decrease (P<0.05) in LL and increases (P<0.05) in above and belowground MS accumulation. Under field conditions, MS accumulation and tillers height over the growing seasons differed among IC (EC × IC interaction; P<0.05). Tiller weight increased (P<0.05) with higher IC and tiller density did not differ (P=0.13) among IC. The PB values ranged from 11.4% to 7.1% (P<0.001) with increasing IC and they were related (r = -0.89; P<0.01) with MS accumulation. In addition, the last one was related to tiller weight (r = 0.81; P<0.001) and tiller height (r = 0.79; P<0.001) but not with tiller density (r = 0.05; P=0.73). The variations found in plant structure would indicate a compensatory capacity of kleingrass and self-regulation of leaf area index in response to defoliation. However, these responses were smaller in magnitude under in field than under greenhouse conditions.

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Keywords

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