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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Water Management Research » Research » Publications at this Location » Publication #325554
Title: Influence of salinity and boron on germination, seedling growth and transplanting mortality of guayule: a combined growth chamber and greenhouse study

Author
item ZHU, HUI - Northeast Institute Of Geography And Agronomy, Cas
item Banuelos, Gary

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2016
Publication Date: 8/11/2016
Citation: Zhu, H., Banuelos, G.S. 2016. Influence of salinity and boron on germination, seedling growth and transplanting mortality of guayule: a combined growth chamber and greenhouse study. Industrial Crops and Products. 92:236-243. doi: 10.1016/j.indcrop.2016.07.027.

Interpretive Summary: Guayule, a native plant in the southwestern United States and northern Mexico, has been exploited as a source of natural rubber for commercial production. Due to guayule’s commercial value and its drought tolerance, guayule has been developed and considered as an alternative crop for arid and semiarid areas of the southwestern United States, north central Mexico, and even the westside of Central California. One drawback in establishing guayule is that there are oftentimes problems with seed germination when it is direct seeded under different soil quality conditions. If this plant is to be considered as an alternative crop for the westside of California, it must be able to grow in poor quality soils. Our results showed that an increased salinity inhibited both germination and seedling growth of six guayule lines tested. In contrast, boron (B) positively influenced (to varied degrees) germination and growth of specific guayule lines AZ-1, 2, and 4) and had no significant negative influence on the other three lines. The combination of 5 mg B/L and salinity of 5 dS/m increased both germination percentages and rates and seedling vigor of some lines. There was no effect on germination percentages for most guayule lines (except for AZ-3) grown in saline B-laden (EC of 10 dS/m, 10 mg B/L) and control (EC of 2.3 dS/m, 0.12 mg B/L) soils under greenhouse conditions. AZ-4 showed even a greater germination percentage in saline B-laden soil than in control soil. AZ-1 and AZ-6 showed greater germination percentages and rates than the other lines, although greater mortality percentage was observed when these AZ-1 and AZ-6 seedlings were transplanted into saline B-laden soils. Our results from both growth chamber and greenhouse experiments indicate that many of the tested guayule lines can successfully germinate in typical but moderate saline B-laden soils present in the West side of central California. Consequently, guayule may be a new crop to consider for planting in this region of California.

Technical Abstract: Guayule (Parthenium argentatum A.Gray), a drought tolerant plant, originating from southwestern United States and northern Mexico, is considered to be a promising rubber-producing plant for arid and semiarid areas. To evaluate the potential of guayule as an alternative crop for saline boron-laden soils in the arid West side of central California, four experiments were conducted to evaluate germination, seedling growth and transplanting mortality of six guayule lines (AZ-1, AZ-2, AZ-3, AZ-4, AZ-5, and AZ-6) under varied salinity (electrical conductivity (EC) of 5, 10, 15, and 20 dS/m) and boron (B) levels (5, 10, 20, 30, and 40 mg/L) under both growth chamber and greenhouse conditions. Overall, increased salinity (especially at levels of EC>10 dS/m) inhibited both germination and seedling growth of all guayule lines. In contrast, B positively influenced (to varied degrees) germination and growth of specific guayule lines (AZ-1, AZ-2, and AZ-4) and had no significant negative influence on the other three lines. The combination of 5 mg B/L and salinity (EC) of 5 dS/m significantly (P<0.05) increased both germination percentages and rates of AZ-4 and AZ-6, and the seedling vigor index (SVI) and length of AZ-1 and AZ-6, SVI of AZ-2, and length of AZ-5, respectively. There was no statistical difference (P>0.05) on germination percentages for most guayule lines (except for AZ-3) grown in saline B-laden (EC of 10 dS/m, 10 mg B/L) and control (EC of 2.3 dS/m, 0.12 mg B/L) soils under greenhouse conditions. AZ-4 showed even a greater germination percentage in saline B-laden soil than in control soil, while AZ-6 showed very small difference between both types of soils. AZ-1 and AZ-6 showed greater germination percentages and rates than the other lines, although greater mortality percentage was observed when these AZ-1 and AZ-6 seedlings were transplanted into saline B-laden soils. Our results from both growth chamber and greenhouse experiments indicate that AZ-4 and AZ-6 can successfully germinate in typical moderate saline B-laden soils present in the West side of central California. Consequently, guayule may be a new crop to consider for planting in lower quality soils of the westside of Central California.