2 research outputs found
Competition and critical periods in spring sugar beet cultivation
High yields with low costs require that sugar beets be kept free of weeds, during critical periods, using labor or chemical
treatments. Since the critical periods for this crop in Castilla – La Mancha (Spain) are unknown, the first goal of this study was to
determine the effect of early and late competition on yield. The second goal was to determine the critical periods, while taking into
consideration the semiarid climatic conditions of this region. Two irrigation farms located in the province of Albacete are dedicated
to sugar beet cultivation. These two farms were chosen to carry out the tests March (140,000–150,000 seeds ∙ ha–1) and harvested in
October. Two simultaneous and complementary experiments were carried out in each year and farm. Two scenarios were considered
with eight different treatments each. In the first one (With Weeds Until – WWU), plots were infested by weeds up to a certain date. In
the second one (Free of Weeds Until – FWU), plots were kept free of weeds up to a certain date. For each test, a randomised experimental
blocked field was designed and there were four repetitions, each of them containing eight elemental plots (12 m2). Each plot
was weeded by hand or weeds were left to grow till a definite date.The results indicated that a 1% loss of yield was reached in the early
competition after 14 days, while a loss of 5% was reached after a period of 41 days after it was infested. The results also indicated that
in late competition, if a crop is kept clean for 124 days and it is infested afterwards, a 1% loss is reached. However, the loss increases
to 5% if the plot is kept clean for 111 days. For a 1% loss the critical period is 110 days and 70 days for a 5% loss