Herbicides are widely used to manage weeds in dry seeded rice systems; however, herbicides alone cannot provide effective and season-long weed control. Therefore, there is a need to integrate herbicide use with other weed management strategies . The use of residue as mulch can sup- press weed growth to some extent in seeded rice, but the combined use of herbicide and mulch may suppress weeds more effectively. Therefore, a field study was conducted to evaluate the combined effects of herbicide and mulch on weed growth and rice yield in a dry-seeded system. Brazil is not self-sufficient in rubber production so that any factor affecting latex extraction can be very deleterious to rubber production. Latex production by rubber trees can be affected by biotic factors such as microorganisms causing plant diseases and other factors increasing the timing to plants reach the maturity for latex extraction . In this way, weed interference is an important issue reducing plant growth and, in consequence, increasing the timing for plant maturity. Weed management during the establishment of commercial tree plantations is a major factor that contributes to improvement of the final yield. Development of a sound vegetation management strategy requires a definite and sequential plan of action .
A good understanding of the basic criteria involved in weed-tree interactions,growth-limiting factors, the minimum tolerable weed thresholds and an understanding of the best parameters of measurement are needed to delineate an appropriate management approach . Researchers have demonstrated that the width of weed control strips reflected in the growth of some trees, such as Coffea arabica and Eucaliptus spp. , but the effect depends on several factors, including weed composition, crop species,and the availability of environmental resources. In function of the importance and the lack of information on weed interference in rubber tree plantation, cannabis drying racks we performed this research aiming 1) to evaluate the growth of rubber tree plants submitted to different weed control strips and 2) to determine the critical width of weed control strip during the establishment of rubber tree plantation. Analyzing the rubber tree growth within each weed control strip during 720 DAP, the best adjusted equation was a logistic model, showing a high significance, normal distribution of residuals, and constant variance of residuals, being well-appropriated to describe the plant behavior and satisfying statistical conditions.This analysis shows the accumulated plant growth within each weed control strip during the whole experimental period. For both plant height and stem diameter, the interval of confidence of the equation parameters b,x0, and y0 was correspondent to all weed control strips, indicating no significant difference. However, the interval of confidence of the equation parameter a was not correspondent to all weed control strips, being also distinct for plant height and stem diameter.For plant height, the interval of confidence of the parameter a in the weedy condition was not correspondent to any weed control strip.
For stem diameter, the interval of confidence of the parameter a in the weedy situation and weed control strips of 50 cm and 100 cm was correspondent, but differing of weed control strips of 150, 200,250, 300, 350, and 400 cm. The parameter a indicates the difference between minimum and maximum values of the growth characteristics, so that higher a values shows a better or a greater plant growth of the rubber trees, as observed when weeds were controlled in larger widths. In this sense, analyzing the plant growth within each weed control strip, the weed control should be performed within strips of 50 cm and 150 cm for plant height and stem diameter, respectively.Analyzing the RGR during 720 DAP, in function of crescent weed control strips, the best adjusted equation was an exponential rising to maximum model, showing a high significance, normal distribution of residuals, and constant variance of residuals , being well-appropriated to describe the plant behavior and satisfying statistical conditions. So, we observed that RGR increased when weed control strips was extended,reaching a maximum value and then keeping constant.