No abstract

No abstract

Geostatistical techniques were used to characterize the spatial relationship between Hordeum spontaneum and Cardaria draba seedling and soil seed bank over the entire growing season of 2004-2005 in three saffron (Crocus sativus L.) fields, located in Southern Khorasan (33° North latitude, 57° East longitude), Iran. The maps of H. spontaneum seed bank density corresponded moderately to those seedling density in a and strongly to those in b and c fields. The emergence percentage of Cardaria draba was higher than for H. spontaneum in all fields. Semivariograms showed spatial autocorrelation in seed bank and seedling populations of H. spontaneum and C. draba in all fields. Grey-scale field maps of C. draba seed banks corresponded visually to maps of seedling populations and could have been used to target control efforts, but visual correspondence between H. spontaneum seed bank and seedling maps was poor.

Minerals in spray carrier water can adversely in uence the activity of weak acid herbicides, thus overcoming them has been considered a main research priority. A series of dose-response pot experiments were conducted to compare the water so ening chemical methods [(NH 4 ) 2 SO 4 , NH 4 NO 3 , C 6 H 8 O 7 , and KHPO 4 ] and a new water so ening physical method (passing through a magnetic eld of 0.7 T) for overcoming antagonism from the carriers containing 0.5 g L -1 of CaCO 3 , MgCO 3 , Na 2 CO 3 , K 2 CO 3 , or Fe 2 (CO 3 ) 3 on imazethapyr (2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-ethyl-3-pyridinecarboxylic acid) activity on jimsonweed (Datura stramonium L.). e imazethapyr activity was signi cantly increased by all methods when distilled water was used as the carrier. e (NH 4 ) 2 SO 4 (relative potency [RP] = 3.52) was the most e ective method, followed by C 6 H 8 O 7 and NH 4 NO 3 (RP = 2.58), a magnetized carrier (RP = 1.83), and then KHPO 4 (RP = 1.48) to improve imazethapyr activity. e imazethapyr activity was clearly antagonized when carbonate salts were added to distilled water. e intensity of the antagonistic e ects depended on the cation's valence and ranked as Fe 2 (CO 3 ) 3 (RP = 0.47) > MgCO 3 (RP = 0.52) = CaCO 3 (RP = 0.53) > K 2 CO 3 (RP = 0.69) = Na 2 CO 3 (RP = 0.66). e application of a magnetized carrier was not as e ective a method for overcoming this antagonism as the addition of (NH 4 ) 2 SO 4 or C 6 H 8 O 7 , but it was more e ective than the addition of NH 4 NO 3 or KHPO 4 . Nonetheless, from di erent points of view-agronomic, environmental, and economic-applying a magnetized carrier is recommended as a technique because it not only needs no chemical but it also causes no side e ects.