Interference of Urochloa plantaginea on Morphophysiology and Yield Components of Black Beans

Abstract

Among the factors which affect crop productivity, there are weeds which compete for environment resources. The objective of this work was to determine the periods of interference of alexandergrass on the morphophysiology and productivity components of black beans. The experiment was conducted in a complete randomized block design with four replications. The bean cultivar of the black type used was IPR Uirapuru, being the treatments separated in two models of interference: in the coexistence group, the crop of the bean lived with the alexandergrass by growing periods of 0, 7, 14, 21, 28, 35, 42 and throughout the cycledays after emergence and throughout the cycle; in the control group the crop was kept free of the infestation for the same periods described previously. At 42 DAE were evaluated the variables related to plant morphology and physiology (height of bean plants, number of trifoliate leaves, dry mass plant, number of grains pods, number od pods plants, stomatal conductance, internal CO2 concentration, photosynthetic activity, efficiency of carboxylation, efficient use of water, transpiration rate). Considering the results, it is possible to conclude that the critical period of interference prevention (CPIP) comprises 24 to 50 DAE, the period before the interference (PBI) was 24 DAE and the total period of interference prevention (TPIP) was 50 days and that the morphological and physiological variables of the plants were negatively affected in the coexistence with the alexandergrass when compared to the treatments kept free of weeds throughout the crop cycle.

Competitive ability of bean cultivars with Urochloa plantaginea

“…Weeds reduce bean grain yields due to competition for environmental resources, such as nutrients, light, and water; in addition, they can release allelopathic compounds to the soil, resulting in qualitative and quantitative losses. They can also be responsible for indirect damage,hosting diseases and insects (10,11,16,21). Weeds at the end of the cycle can also interfere with the quality by depreciating the harvested product and making it difficult to harvest, either manual or mechanical (11,14,24).…”

Interferência e nível de dano econômico de papuã em feijoeiro em função da densidade de plantas

“…When comparing the losses of grain yields caused by an infestation of one against 80 plants m -2 of alexandergrass, in the average of all sowing densities (140,000, 180,000, 220,000 and 260,000 plants ha -1 ) there was an increase to 20 times. Knowing that alexandergrass is a companion weed to summer crops grown in southern Brazil (KALSING & VIDAL 2013), which appears at high densities and that densities exceeding 80 plants m -2 are easily obtained (FRANCESCHETTI et al 2019), it is clear that its management becomes crucial to avoid high grain yield losses of the bean plant.…”

“…Among the environmental conditions the competition with weeds can cause more than 71% reductions in grain yield (PARREIRA et al 2014, GALON et al 2016 when not properly controlled and in the critical period of competition, which goes from 24 to 50 days after emergence (FRANCESCHETTI et al 2019).…”

“…Bean has low competitiveness because of its short cycle, C3 metabolism slowly first growth, and superficial root system, which make the crop suffer from competition for water, light, and nutrients when infested by weeds, which in most situations show greater competitiveness than crops (MANABE et al 2015, FRANCESCHETTI et al 2019.…”

“…One of the most damaging weeds in the bean crop is alexandergrass (Urochloa plantaginea), which appears in the middle of many crops in various locations in Brazil, causing severe damage to the productivity and profitability of crops (KALSING & VIDAL 2013, TAVARES et al 2013, FRANCESCHETTI et al 2019. Alexandergrass belongs to the Poaceae family with C4 metabolism and has a high competitiveness capacity when it infects the bean plant since it presents a rapid growth and development, as well as the ability to infect large extensions of land, consequently causing site domination and shading of the crop (KALSING & VIDAL 2013, TAVARES et al 2013, FRANCESCHETTI et al 2019.…”