245-21 Harvest Management Based On Leaf Stage of a Tetraploid Vs. a Diploid Cultivar of Annual Ryegrass.

Poster Number 618

See more from this Division: C06 Forage and Grazinglands
See more from this Session: General Forage and Grazinglands: II

Tuesday, November 5, 2013
Tampa Convention Center, East Exhibit Hall

Juan K. Q. Solomon, 1664 N. Virginia Street, University of Nevada-Reno, Reno, NV and Bisoondat Macoon, 1676 Brown Loam Road, Mississippi State University, Raymond, MS
Abstract:
The act of defoliation creates a major encumbrance on pasture plants with its impact being dependent on the timing and severity of defoliation.  A 2-yr study was conducted at Raymond, MS to quantify forage production, morphological characteristics and nutritive value between a tetraploid vs. a diploid annual ryegrass cultivars harvested at three different leaf stages and two stubble heights.  Treatments were two annual ryegrass cultivars ‘Maximus’ a tetraploid and ‘Marshall’ a diploid, three different leaf stages (2-, 3-, and 4-leaves per tiller-1), and two residual stubble heights (5- and 10-cm RSH) arranged in a 3 × 2 × 2 factorial combinations in a randomized complete block design experiment with four replications for each treatment combinations.  Responses were considered different at P < 0.05.  In 2011, there was a linear increase in forage harvested as defoliation increased from 2- (7.3 Mg DM ha-1) to 4-leaf stage (8.8 Mg DM ha‑1) and in 2012, there was a quadratic response of forage harvested to defoliation interval.  At 5-cm RSH forage harvested (7.9 Mg DM ha-1) tended to be greater than at 10-cm RSH (7.5 Mg DM ha-1).  Tiller density was not different (P = 0.394) among the three defoliation intervals but tiller density was less for Maximus (1191 tillers m-2) than Marshall (1383 tillers m-2).  In both years, at 5-cm RSH there was a linear increase in stubble water‑soluble carbohydrate (WSC) content from 2- (4.8 mg tiller-1) to 4-leaf stage (6.9 mg tiller-1) and at 10‑cm RSH there was a quadratic response of stubble WSC content to defoliation interval.  Water-soluble carbohydrate content of stubble was greater for Maximus (7.9 mg tiller-1) than Marshall (6.2 mg tiiler-1).  The responses of leaf blade proportion to defoliation interval were mostly a quadratic decreased from 2- to 4-leaf stage and greater for Maximus by 9% than Marshall.  In 2012, at 5-cm there was a linear increase in whole plant WSC concentration from 2- (84.1 g kg-1 DM) to 4-leaf stage (133.4 g kg-1 DM) however, whole plant WSC concentration was not different between Maximus and Marshall.  There was a linear (2011) and quadratic (2012) decrease in digestibility from 2- (801 g kg-1 DM) to 4-leaf stage (729 g kg-1 DM) but digestibility was not different between Maximus and Marshall.  There was a dichotomy in forage response in terms of forage harvested and nutritive value to defoliation intervals based on leaf stage and stubble height of annual ryegrass.  Harvesting at 5-cm RSH did not result in less forage harvested than at 10-cm for Maximus and Marshall annual ryegrass. Therefore, the choice of cultivar, defoliation interval and intensity should be made in the context of farmer’s production system and location.

See more from this Division: C06 Forage and Grazinglands
See more from this Session: General Forage and Grazinglands: II