|Bekaardt, C -|
|Fenwick, J -|
Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 12, 2009
Publication Date: May 1, 2010
Citation: Bekaardt, C.R., Coffelt, T.A., Fenwick, J.R., Wiesner, L.E. Environmental, irrigation and fertilization impacts on the seed quality of guayule (Parthenium argentatum Gray). Industrial Crops and Products (2010), Vol. 31, Issue 3, pp. 427-436. Interpretive Summary: Increasing the understanding of factors that affect seed quality in guayule is needed in order to develop reliable methods of direct seeding to reduce production costs. A two year study at four locations was conducted to determine environmental effects such as irrigation, nitrogen fertility, temperature, and wind speed on guayule seed germination and quality. The largest factor effecting seed quality was the presence of seeds without embryos. The results from this study will help researchers and guayule seed producers develop production practices that maximize seed with embryos and choose methods in seed cleaning that can remove seed without embryos.
Technical Abstract: The commercialization of guayule for hypoallergenic latex has renewed interest in factors that affect seed quality. The objective of this study was to determine the seed quality of guayule (Parthenium argentatum Gray) grown under various field conditions in Arizona, USA. In experiment I guayule lines AZ-2, AZ-4, AZ-R2 and 11591 were compared at locations in Marana, Maricopa, Yuma Mesa and Yuma Valley. In experiment II guayule lines AZ-2 and 11591 were compared under integrated irrigation of 40%, 60% and 80% field capacity and fertilization at low and high levels of nitrogen, at Maricopa. Germination, viability of ungerminated achenes, empty achene production and achene moisture content were determined for harvested achenes. In experiment I a line x location interaction occurred for normal germination, empty achenes and achene fresh weight. Line AZ-4 had the highest germination of 59% at the Yuma Valley location. Empty achenes were the highest in Marana for line 11591 at 56%. In experiment II normal germination was affected by the line, irrigation and fertilization factors. The highest germination of 66% with line 11591, 55% at 60% irrigation and 56% at high fertilization was recorded. Empty achenes were the highest with line AZ-2 at 27%. Correlations of normal germination vs. maximum temperature, empty achenes vs. total rainfall and empty achenes vs. average wind speed were positive. Negative correlations occurred for empty achene vs. maximum temperature, normal germination vs. total rainfall and normal germination vs. average wind speed. The quality of guayule seed under both experimental conditions was severely decreased by empty achene production, which seems due to genetic variability and environmental conditions during flower bloom.