Efeito da Época de Plantio e do Arranjo Espacial em Feijoeiro Comum (Phaseolus vulgaris) com e Sem Infestação de Plantas Daninhas

pd Planta Daninha Planta daninha 0100-8358 1806-9681 Sociedade Brasileira da Ciência das Plantas Daninhas RESUMO Um experimento foi conduzido em 2013 em Kelachay, no norte do Irã, para avaliar o efeito da época de semeadura e do arranjo espacial na produtividade do feijoeiro com e sem infestação de plantas daninhas. O delineamento experimental foi de blocos casualizados, em esquema fatorial, com três repetições. Os fatores foram época de plantio (10 de agosto e 20 de agosto), arranjo espacial (sistema de plantio quadrado e retangular, com espaçamento de plantio de 30 x 30 cm e 45 x 20 cm, respectivamente), e sistema de manejo de plantas daninhas (ausência e presença de plantas daninhas, com ou sem roçada durante todo o período de crescimento, respectivamente). Os resultados mostraram que o principal efeito da época de semeadura foi significativa apenas para número de vagens por planta e número de sementes por vagem. Ao mesmo tempo, número de vagens por planta, número de sementes por vagem, comprimento de vagem e produtividade de grãos sofreram influência significativa do padrão espacial. Os resultados de análise de variância indicaram também que todas as características, exceto comprimento de vagem, sofreram influência significativa dos sistemas de manejo de plantas daninhas. Além disso, o efeito da época de plantio e do padrão espacial foram nãosignificativa para massa seca de plantas daninhas. A comparação das médias indicou um aumento significativo na produtividade de sementes no sistema de plantio quadrado (1.055 kg ha-1) em comparação ao retangular (971 kg ha-1). A roçada de ervas daninhas também indicou um aumento geral de 12% e 8% no rendimento de grãos e vagem em comparação ao controle, respectivamente. Com base nos resultados deste estudo, recomenda-se o controle de plantas daninhas, bem como o sistema de plantio quadrado, para a obtenção de maior rendimento de sementes de feijoeiro comum. INTRODUCTION Grain legumes, as a protein-rich food, play an important role in human nutrition, especially in developing countries. Alone, they contribute up to 33% of the dietary protein needs of humans (Vance et al., 2002). Common bean (Phaseolus vulgaris) is a warmseason annual legume crop grown primarily for its protein and energy-rich dry seeds. Bean grains are a good source of iron and zinc (Buruchara et al., 2011) and have a low glycemic index (Widers, 2006). Worldwide, an estimated 23.1 million tons of common bean is produced annually on about 8.7 million hectares (FAO, 2014). In 2013, common bean was planted on 98,000 hectares in Iran, with a total production of almost 253,000 tons (FAO, 2014). In Northern Iran, common bean is cultivated in early May and harvested in early July. Moreover, after rice harvesting in August, this crop is cultivated in rice fields with good drainage, and harvested in midNovember. Weeds are one of the major biological constraints in crop production and, therefore, their control is an important component of any crop production system. Common bean plants are sensitive to weed competition, mainly during the early vegetative growth stages (Blackshaw, 1991). Pynenburg et al. (2011) found that seed yield in dry bean (Phaseolus vulgaris) was reduced up to 85% as a result of season-long weed competition. Chemical weed control is still the predominant component of weed management in crop production. However, the excessive use of herbicides has already led to serious problems such as environmental pollution and evolution of resistance to herbicides in weed species (Rao et al., 2007). These problems highlighted the need for integrated weed management (IWM) programs (Hill et al., 1994). Manipulation in agronomic practices, such as planting date and planting pattern, may increase crop competitiveness against weeds. Planting date is one of the most important cultural practices for the success of common bean production in Northern Iran, especially when the crop is sown in August. Early planting of common bean can enable the crop to set and fill grain before the onset of late-fall chilling. Early planting can also provide the potential for producing a larger crop canopy earlier in the growing season, which can better utilize solar radiation for photosynthesis (De Bruin et al., 2010). Moreover, early planting can increase crop competitiveness against weeds, especially against late-emerging ones. However, very early planting of common bean exposes the germinating seeds to dry and warm conditions and, therefore, it has the potential to reduce stands and to cause uneven seedling emergence. Combining uneven seedling emergence and lower populations under these conditions may cause greater yield reductions. In contrast, late planting date causes the reproductive growth stage of the crop to face the fall chilling, which ultimately lowers yield. Unfortunately, the sensitivity of common bean to low temperature (Badowiec & Weidner, 2014) may be troublesome in temperate climate regions where the transitional drops of temperature occur frequently during late growing season (Figure 2). Srinivasan et al. (1999) reported yield reduction in chickpea due to chilling stress during the reproductive stage in high latitudes and hilly areas of Asia. Several studies have reported that planting date had a significant effect on crop growth and yield (Darby & Lauer, 2002; Hossain et al., 2003; Bhardwaj et al., 2004; Schwarte et al., 2005). Crop spatial pattern is another agronomic factor that can affect grain yield and crop competitiveness against weeds (Olsen et al., 2012). It has been suggested that uniform planting pattern increases the spatial uniformity in leaf area index (LAI), reduces mutual shading, and hastens canopy closure, all of which result in increased radiation interception (RI) by the canopy (Olsen & Weiner, 2007) and increased crop growth and yield (Mashingaidze et al., 2009). At the same time, an equidistant spacing of crop plants may reduce light penetration or affect light quality (or both) under the crop canopy. This may restrict seed germination of some weed species, suppress weed seedling growth, and reduce seed production by weed plants (Mashingaidze et al., 2009). In a uniform pattern, intra-specific competition within the crop is delayed, while inter-specific competition with weeds begins sooner. This allows the crop population to shade and suppress the weeds (Weiner et al., 2010). Some researchers (Weiner et al., 2001; Olsen & Weiner, 2005; Olsen et al., 2012; Dusabumuremyi et al., 2014) noted that increased crop uniformity had a negative effect on weed biomass. However, some other researchers (Teasdale, 1995; Westgate et al., 1997) reported that crop growth and yield does not always increase in narrow-row planting. Weiner et al. (2001) reported that the advantage of uniform planting pattern occurs only when weeds are present, while in their absence or when they are well controlled, uniform planting pattern may have no superiority over row planting pattern. Fanadzo et al. (2007) reported that under low water and nutrient supply, maize grain yield reduced with a reduce in row spacing, which was attributed to increased intra-specific competition for water and nutrients. This study aimed to evaluate the effects of planting date and spatial pattern on common bean growth and yield under weedfree and weed-infested plots. MATERIALS AND METHODS Experimental site and design This experiment was conducted in Kelachay, Northern Iran, in 2013. Weekly precipitation and temperature during the growing period of common bean were presented in Figures 1 and 2, respectively. Table 1 presents some soil properties of the experimental field. The experimental treatments were arranged in a randomized complete block design with three replicates. This consisted of a factorial combination of two planting dates (10 August and 20 August), two spatial arrangements (square and rectangular planting pattern, with a planting distance of 30 x 30 cm and 45 x 20 cm, respectively) and two weed management regimes (weed-free and weedy conditions, weeded and not weeded throughout the growing season, respectively). Each plot consisted of six 5-meter long rows Figure 1 - Weekly precipitation during common bean growing period. Figure 2 - Weekly temperatures (maximum, minimum and average) during common bean growing period. separated from the neighboring plot by one empty row. Crop management Cultivation was started in August by preparing the soil with two perpendicular passes of disk harrow. Just before final land preparation, N, P and K fertilizers were applied to the plots as recommended doses; i.e., 15 kg N ha-1 (as starter in the form of urea), 50 kg K2O ha-1 (as potassium sulphate), and 100 kg ha-1 P2O5 as triple super phosphate. Weed seedlings were removed manually just before seed planting. Plants were seeded on 10 and 20 August. To avoid water stress, the plots were irrigated as required. In weedfree plots, manual weeding was performed throughout the growing season. Since pests or diseases did not affect the crop, no pesticide was used during the experiment. Crop measurements Plants from planting dates of 10 and 20 August were harvested on 11 November and 3 December, respectively. At maturity stage, yield components, viz. number of pod per plant, number of seeds per pod, and 100-seed weight were determined on a randomly selected subsample of five plants (Malik et al., 1993). Green pods were harvested from the plants grown in half portion of each plot. The rest half of the crop of each plot was kept to allow the pods to get maturity and then the matured pods were harvested, hand threshed, and weighed. Seed yield was adjusted to 16% seed moisture content. To minimize the border effect, all samplings in each plot were done only on four central rows of 4 m (leaving two border rows and 0.5 m at the beginning and at the end of each row). Weed measurement Biomass of the weeds was determined by collecting the above ground portion of the weeds from four randomly selected 50 x 50 cm quadrates within each weedy plot at maturity stage, dried at 70 oC for 3 days, and weighed in gram. Then, it was expressed as the weed dry weight per m2. Table 1 - Some soil properties (0-30 cm) of the experimental field prior to sowing OC (%) pH Texture EC (ds m -1 ) Total N (%) P (mg kg -1 ) K (mg kg -1 ) 4.21 6.9 loam 0.46 0.35 35.2 198.2 OC, Organic Content; pH, potential of Hydrogen; EC, Electrical Conductivity; N, Nitrogen; P, Phosphorus; K, Potassium. Statistical Analyses Data were subjected to analysis of variance (ANOVA) using PROC GLM in SAS (SAS, 2004). Means were compared at the 5% level of significance using Fisher's protected least significant difference (LSD). When the interaction among factors was significant (for seed number per plant, 100-seed weight and pod length), means for the interaction effects (with standard error) were compared, but when the interactions were not significant (pod number per plant, pod and seed yield), means for main effects were presented. RESULT AND DISCUSSION Weed biomass and composition of weed communities The most dominant weed species in the experimental field were Amaranthus retofelexus, Setaria viridis, Datura stramonicum, Chenopodium album, Echinochloa crus-galli, Portulaca oleracea, Paspalum dilatatum, Cynodon dactylon and Cyperus esculentus ANOVA indicated that the main effect of spatial arrangement was significant for weed biomass, while the main effect of planting date and the interaction between spatial arrangement and planting date were not significant (Table 2). Weed biomass was 266.4 and 254 g m-2for planting dates of 10 and 20 August, respectively. Weed biomass was significantly higher in the rectangular planting pattern (288.2 g m-2) than in the square planting pattern (232.2 g m-2). This result agrees with those reported by Holmes & Sprague (2013), Acciares & Zuluaga (2006), and Blackshaw et al. (1999), who found that narrowrow square planting pattern suppressed weed growth more effectively than wide-row planting pattern in beans. Moreover, Mashingaidze et al. (2009) reported that narrow rows in corn fields reduce biomass and seed production of weeds. Table 2 - Mean squares of ANOVA for weed biomass as affected by planting date (D) and spatial arrangement (S) Source of variance Df Weed biomass R 2 582.2 ns Planting date (D) 1 463.2ns Spatial pattern (S) 1 9408.0 ** D x S 1 1.0 ns Error 14 891.4 CV (%) - 11.5 *, ** represent significance at 0.05 and 0.01probability levels, respectively. ns represents no significant difference. Pod and seed yield The main effect of weed management regime was significant (p ≤ 0.01) for pod yield, while the main effects of planting date and spatial arrangement were not significant. Moreover, all two- and three-way interaction effects were non-significant (Table 3). Regardless of planting date and spatial arrangement, pod yield was reduced by 7.6% due to weed competition (Table 4). Seed yield was affected significantly only by weed management regime and spatial arrangement at 0.01 and 0.05 probability levels, respectively (Table 3). Regardless of planting date and weed management regime, the plants produced more seed yield in uniform planting pattern compared to rectangular planting pattern (Table 4). Similarly, Dusabumuremyi et al. (2014) reported that bean yield was influenced significantly by planting pattern. They found that bean yield was reduced significantly by 22% in wide-row planting pattern compared to narrow-square planting pattern. They noted that narrow rows increase the evenness of LAI distribution, reduce mutual shading, and shorten the time taken by the canopy to achieve full ground cover. These increase radiation interception by the canopy during the season and enhance crop growth and seed yield. Moreover, Acciaresi & Chidichimo (2007)reported that reduced intra-specific competition (for water, mineral nutrients, and radiation) in the square planting pattern increased bean growth and yield. Seed yield was significantly greater in weed-free plots compared to weedy plots as averaged across planting date and spatial arrangement. The reduction in seed yield in the presence of weeds can be attributed to inter-specific competition between crop and weeds for light, water, and nutrient elements. Aguyoh & Masiunas (2003) reported that snap bean yield was reduced by 13%-58% at densities 0.5-8 of redroot pigweed plants per meter, respectively. Vogt et al. (2013)reported that the losses of grain yield in black common bean genotypes due to weed interference ranged from 30.8% to 54.9%. Pod number per plant ANOVA indicated that the main effects of planting date, spatial arrangement, and weed management regime were significant for pod number per plant, but all two- and threeway interaction effects were not significant (Table 3). Regardless of spatial arrangement and weed management regime, pod number per plant increased by 26% as planting date went from 10 to 20 August (Table 4). Plants in uniform planting pattern produced higher pods compared to those in rectangular planting pattern as averaged across planting date and weed management regime (Table 4). This result is consistent with the result of Dusabumuremyi et al. (2014), who reported that number of pods per plant was higher in the narrow-row planting pattern than in the wide-row planting pattern. Regardless of planting date and spatial arrangement, pod number per plant was significantly higher under weed-free condition compared to weedy condition (Table 4). Pod number per plant reduced by 10% due to weed interference. Similarly, Malik et al. (1993) reported that season-long weed competition significantly reduced pod number per plant in white bean (Phaseolus vulgaris). Woolley et al. (1993) noted that in bean plants, pod number was the most sensitive yield component to weed competition. Table 3 - Mean squares of ANOVA for pod number per plant (PN), seed number per plant (SN), 100-seed weight (100-SW), pod length (PL), pod yield (PY), and seed yield (SY) as affected by planting date (D), spatial arrangement (S), and weed management regime (W) Source of variance df PN SN Thgw PL PY SY R 2 0.27 ns 0.003 ns 3.706 ns 3.60 * 34948.7 ns 20362.1 ns Planting date (D) 1 20.35 ** 0.032 ns 0.003 ns 2.28 ns 1552.0 ns 4760.1 ns Spatial pattern (S) 1 2.47 ** 0.163 ** 1.760 ns 19.98 ** 18760.0 ns 42168.1 * Weed management regime (W) 1 2.83 ** 0.123 ** 83.2 ** 1.50 ns 140607.0 ** 57624.0 ** D x S 1 0.40 ns 0.025 * 93.2 ** 8.28 ** 14065.0ns 170.6 ns D x W 1 0.22 ns 0.564 ** 15.2 ns 0.08 ns 273.3 ns 5104.1 ns S x W 1 0.30 ns 0.728 ** 18.9 ns 1.08 ns 4959.3 ns 480.1 ns S x D x W 1 0.51 ns 1.050 ** 3.3 ns 0.22 ns 29051.0 ns 4615.5 ns Error 14 0.15 0.004 9.3 1.71 14002.1 7490.6 CV (%) - 5.1 3.2 5.5 11.3 9.8 8.9 *, ** represent significance at 0.05 and 0.01 probability level, respectively. ns represents no significant difference. Table 4 - Pod number per plant (PN), seed number per plant (SN), 100-seed weight (SW), pod length (PL), pod yield (PY), and seed yield (SY) as affected by planting date, spatial arrangement and weed management regime Means followed by the same letter within a column among planting date, spatial arrangement or weed management regime are not significantly different according to Fisher's protected LSD (P≤0.05). Seed number per pod Seed number per pod was not influenced significantly by planting date, while the main effects of spatial arrangement and weed management regime, and all two- and threeway interaction effects were significant (Table 3). This is contrary to the findings of Dusabumuremyi et al. (2014), who found that seed number per pod was not influenced significantly by planting pattern. The highest seed number per pod was observed for plants seeded on 20 August in square planting pattern under weed-free condition, while the lowest one was recorded for plots seeded on 20 August in rectangular planting pattern under weedy condition (Table 5). Seed number per pod was significantly lower for plants grown under weedy condition compared to those grown under weed-free condition (Table 4). This finding is consistent with that of Malik et al. (1993) for white bean, who reported that seed number per plant was reduced significantly by weed competition. Table 5 - Effect of spatial arrangement × planting date × weed management regime interaction on seed number per pod Hundred seed weight Weed management regime and spatial arrangement × planting date interaction had significant effect on 100-seed weight (Table 3). Weed competition reduced significantly 100-seed weight by 6.5% as averaged across planting date and spatial arrangement (Table 4). Malik et al. (1993) also reported the reduction in 100-seed weight under weedinfested condition for white bean. When plants were seeded on 10 August, 100-seed weight was significantly higher in rectangular planting pattern compared to uniform planting pattern. In contrast, when plants were seeded on 20 August, plants in uniform planting pattern had significantly higher 100-seed weight compared to those in rectangular planting pattern (Figure 3). Dusabumuremyi et al. (2014) reported that there was no significant difference in 1000-seed weight between square and wide-row planting patterns. Figure 3 - Spatial arrangement x planting date interaction effect on 100-seed weight. Vertical bars represent ± 1 SE of means. Pod length Spatial arrangement and spatial arrangement x planting date interaction had significant effect on pod length. Other main effects, two- and three-way interaction effects, were not significant for pod length. Regardless of planting date and weed management regime, significantly greater pod length was recorded in plots with the uniform planting pattern (12.5 cm) compared with the plots with the wide-row planting pattern (10.6 cm). When plants were seeded on 10 August, pod length was significantly greater in the uniform planting pattern compared to the wide-row planting pattern. In contrast, there was no significant difference in pod length between uniform and wide-row planting patterns for plants seeded on 20 August (Figure 4). Akter et al. (2013) reported that pod length in mung bean (Vigna radiata) was reduced significantly due to weed interference. Figure 4 - Spatial arrangement x planting date interaction effect on pod length. Vertical bars represent ± 1 SE of means. In conclusion, this experiment illustrated that plants in a square planting arrangement produced significantly greater seed yield compared to those in a rectangular planting pattern. In the rectangular arrangement, due to weed competition, seed and pod yields were reduced by 11.6% and 7.6%, respectively. Based on the results of this study, weed control, as well as square planting pattern, are recommended for obtaining the highest seed and pod yields in common bean. LITERATURE CITED ACCIARESI, H. A.; CHIDICHIMO, H. O. Spatial pattern effect on corn (Zea mays) weed competition in the humid Pampas of Argentina. Inter. J. Pest Manage., v. 53, n. 1, p. 195-206, 2007. ACCIARESI H. A. CHIDICHIMO H. O Spatial pattern effect on corn (Zea mays) weed competition in the humid Pampas of Argentina Inter. J. Pest Manage. 53 1 195 206 2007 ACCIARESI, H. A.; ZULUAGA, M. S. Effect of plant row spacing and herbicide use on weed aboveground biomass and corn grain yield. Planta Daninha, v. 24, n. 2, p. 287-293, 2006. ACCIARESI H. A. ZULUAGA M. S Effect of plant row spacing and herbicide use on weed aboveground biomass and corn grain yield Planta Daninha 24 2 287 293 2006 AGUYOH, J. N.; MASIUNAS, J. B. Interference of redroot pigweed (Amaranthus retroflexus) with snap beans. Weed Sci., v. 51, n. 2, p. 202-207, 2003. AGUYOH J. N. MASIUNAS J. B Interference of redroot pigweed (Amaranthus retroflexus) with snap beans Weed Sci. 51 2 202 207 2003 AKTER, R. et al. Effect of weeding on the growth, yield and yield contributing characters of mungbean (Vigna radiata L.). J. Bangladesh Agric. Univ., v. 11, n. 1, p. 53-60, 2013. AKTER R. Effect of weeding on the growth, yield and yield contributing characters of mungbean (Vigna radiata L ). J. Bangladesh Agric. Univ. 11 1 53 60 2013 BADOWIEC, A.; WEIDNER, S. Proteomic changes in the roots of germinating Phaseolus vulgaris seeds in response to chilling stress and post-stress recovery. J. Plant Physiol., v. 171, n. 6, p. 389-398, 2014. BADOWIEC A. WEIDNER S Proteomic changes in the roots of germinating Phaseolus vulgaris seeds in response to chilling stress and post-stress recovery J. Plant Physiol. 171 6 389 398 2014 BHARDWAJ, H. L. et al. White lupin performance and nutritional value as affected by planting date and row spacing. Agron. J., v. 96, n. 2, p. 580-583, 2004. BHARDWAJ H. L. White lupin performance and nutritional value as affected by planting date and row spacing Agron. J. 96 2 580 583 2004 BLACKSHAW, R. E. Hairy nightshade (Solanum sarrachoides) interference in dry beans (Phaseolus vulgaris). Weed Sci., v. 39, n. 1, p. 48-53, 1991. BLACKSHAW R. E Hairy nightshade (Solanum sarrachoides) interference in dry beans (Phaseolus vulgaris) Weed Sci. 39 1 48 53 1991 BLACKSHAW, R. E. et al. Canopy architecture, row spacing and plant density effects on yield of dry bean (Phaseolus vulgaris) in the absence and presence of hairy nightshade (Solanum sarrachoides). Can. J. Plant Sci., v. 79, n. 4, p. 663-669, 1999. BLACKSHAW R. E. Canopy architecture, row spacing and plant density effects on yield of dry bean (Phaseolus vulgaris) in the absence and presence of hairy nightshade (Solanum sarrachoides) Can. J. Plant Sci. 79 4 663 669 1999 BURUCHARA, R. et al. Development and Delivery of bean varieties in africa: the Pan-Africa bean research Alliance (PABRA) model. Afr. Crop Sci. J., v. 19, n. 4, p. 227-245, 2011. BURUCHARA R. Development and Delivery of bean varieties in africa: the Pan-Africa bean research Alliance (PABRA) model Afr. Crop Sci. J. 19 4 227 245 2011 DARBY, H. M.; LAUER, J. G. Harvest date and hybrid influence on corn forage yield, quality, and preservation. Agron. J., v. 95, n. 3, p. 559-566, 2002. DARBY H. M. LAUER J. G Harvest date and hybrid influence on corn forage yield, quality, and preservation Agron. J. 95 3 559 566 2002 DE BRUIN, J. L., et al. Soybean photosynthetic rate and carbon fixation at early and late planting dates. Crop Sci., v. 50, n. 6, p. 2516-2524, 2010. DE BRUIN J. L., Soybean photosynthetic rate and carbon fixation at early and late planting dates Crop Sci. 50 6 p25-252 2010 DUSABUMUREMYI, P. et al. Narrow row planting increases yield and suppresses weeds in common bean (Phaseolus vulgaris L.) in a semi-arid agro-ecology of Nyagatare, Rwanda. Crop Protect., v. 64, n. 1, p. 13-18, 2014. DUSABUMUREMYI P. Narrow row planting increases yield and suppresses weeds in common bean (Phaseolus vulgaris L.) in a semi-arid agro-ecology of Nyagatare, Rwanda Crop Protect. 64 1 13 18 2014 FANADZO, M. et al. Narrow rows and high maize densities reduce maize grain yield but suppress weeds under dryland conditions in Zimbabwe. J. Agron., v. 6, n. 4, p. 566-570, 2007. FANADZO M. Narrow rows and high maize densities reduce maize grain yield but suppress weeds under dryland conditions in Zimbabwe J. Agron. 6 4 566 570 2007 FOOD AND AGRICULTURAL ORGANIZATION - FAO. FAOSTAT statistics database [Online]. <Available at http:// http://faostat.fao.org> 2014. FOOD AND AGRICULTURAL ORGANIZATION - FAO FAOSTAT statistics database [Online] 2014 http://faostat.fao.org HILL, J. E. et al. Rice weeds control: current technology and emerging issues in the United States. In: TEMPERATE RICE CONFERENCE, 1994, Yanco, New South Wales, Australia, 21-24 February. Proceedings... Yanco: 1994. p. 377-391. HILL J. E. Rice weeds control: current technology and emerging issues in the United States TEMPERATE RICE CONFERENCE 1994 Yanco, New South Wales, Australia Proceedings... Yanco 1994 377 391 HOLMES, R. C.; SPRAGUE, C. L. Row width affects weed management in type II black bean. Weed Technol., v. 27, n. 3, p. 538-546, 2013. HOLMES R. C. SPRAGUE C. L Row width affects weed management in type II black bean Weed Technol. 27 3 538 546 2013 HOSSAIN, I. et al. Planting date influence on dual-purpose winter wheat forage yield, grain yield, and test weight. Agron. J., v. 95, n. 5, p. 1179-1188, 2003. HOSSAIN I. Planting date influence on dual-purpose winter wheat forage yield, grain yield, and test weight Agron. J. 95 5 1179 1188 2003 MALIK, V. S. et al. Interaction of white bean (Phaseolus vulgaris L.) cultivars, row spacing and seeding density with annual weeds. Weed Sci., v. 41, n. 1, p. 62-68, 1993. MALIK V. S. Interaction of white bean (Phaseolus vulgaris L.) cultivars, row spacing and seeding density with annual weeds Weed Sci. 41 1 62 68 1993 MASHINGAIDZE, A. B. et al. Narrow rows reduce biomass and seed production of weeds and increase maize yield. Ann. Appl. Biol., v. 155, n. 2, p. 207-218, 2009. MASHINGAIDZE A. B. Narrow rows reduce biomass and seed production of weeds and increase maize yield Ann. Appl. Biol. 155 2 207 218 2009 OLSEN, J.; WEINER, J. The influence of Triticum aestivum density, sowing pattern and nitrogen fertilization on leaf area index and its spatial variation. Basic Appl. Ecol., v. 8, n. 3, p. 252-257, 2007. OLSEN J. WEINER J The influence of Triticum aestivum density, sowing pattern and nitrogen fertilization on leaf area index and its spatial variation Basic Appl. Ecol. 8 3 252 257 2007 OLSEN, J. M. et al. How important are crop spatial pattern and density for weed suppression by spring wheat?. Weed Sci., v. 60, n. 3, p. 501-509, 2012. OLSEN J. M. How important are crop spatial pattern and density for weed suppression by spring wheat? Weed Sci. 60 3 501 509 2012 OLSEN, J.; WEINER, J. Effects of density and spatial pattern of winter wheat on suppression of different weed species. Weed Sci., v. 53, n. 5, p. 690-694, 2005. OLSEN J. WEINER J Effects of density and spatial pattern of winter wheat on suppression of different weed species Weed Sci. 53 5 690 694 2005 PYNENBURG, G. M. et al. The interaction of annual weed and white mold management systems for dry bean production in Canada. Can. J. Plant Sci., v. 91, n. 3, p. 587-598, 2011. PYNENBURG G. M. The interaction of annual weed and white mold management systems for dry bean production in Canada Can. J. Plant Sci. 91 3 587 598 2011 RAO, A. N. et al. Weed management in direct seeded rice. Adv. Agron., v. 93, n. 1, p. 153-255, 2007. RAO A. N. Weed management in direct seeded rice Adv. Agron. 93 1 153 255 2007 SAS. SAS Version 9.1. Cary: SAS Institute, 2004. SAS SAS Version 9.1. Cary SAS Institute 2004 SCHWARTE, A. J. et al. Planting date effects on winter triticale dry matter and nitrogen accumulation. Agron. J., v. 97, n. 5, p. 1333-1341, 2005. SCHWARTE A. J. Planting date effects on winter triticale dry matter and nitrogen accumulation Agron. J. 97 5 1333 1341 2005 SRINIVASAN, A. et al. Cold tolerance during early reproductive growth of chickpea (Cicer arietinum L.): genetic variation in gamete development and function. Field Crops Res., v. 60, n. 2, p. 209-222, 1999. SRINIVASAN A. Cold tolerance during early reproductive growth of chickpea (Cicer arietinum L.): genetic variation in gamete development and function Field Crops Res. 60 2 209 222 1999 TEASDALE, J. R. Influence of narrow row/high population corn (Zea mays) on weed control and light transmittance. Weed Technol., v. 9, n. 1, p. 113-118, 1995. TEASDALE J. R Influence of narrow row/high population corn (Zea mays) on weed control and light transmittance Weed Technol. 9 1 113 118 1995 VANCE, C. P. Root-bacteria interactions: symbiotic nitrogen fixation. In: WAISEL, Y; ESHEL, A.; KAFKATI, U. (Ed.) Plant roots: The Hidden Half, Ed 3. New York: Marcel Dekker, 2002. p. 839-867. VANCE C. P. Root-bacteria interactions: symbiotic nitrogen fixation. WAISEL Y ESHEL A KAFKATI U Plant roots: The Hidden Half 3 New York Marcel Dekker 2002 839 867 VOGT, G. A. et al. Competitive ability of black common bean genotypes with weeds. Ci. Agrotec., v. 37, n. 5, p. 397-403, 2013. VOGT G. A. Competitive ability of black common bean genotypes with weeds Ci. Agrotec. 37 5 397 403 2013 WEINER, J. et al. Evolutionary Agroecology: the potential for cooperative, high density, weed-suppressing cereals. Evol. Appl., v. 3, n. 5/6, p. 473-479, 2010. WEINER J. Evolutionary Agroecology: the potential for cooperative, high density, weed-suppressing cereals Evol. Appl. 3 5/6 473 479 2010 WEINER, J. et al. Suppression of weeds by spring wheat (Triticum aestivum) increases with crop density and spatial uniformity. J. Appl. Ecol., v. 38, n. 4, p. 784-790, 2001. WEINER J. Suppression of weeds by spring wheat (Triticum aestivum) increases with crop density and spatial uniformity J. Appl. Ecol. 38 4 784 790 2001 WESTGATE, M. E. et al. Rapid canopy closure for maize production in the northern US Corn Belt: radiation use efficiency and grain yield. Field Crops Res., v. 49, n. 2/3, p. 249-258, 1997. WESTGATE M. E. Rapid canopy closure for maize production in the northern US Corn Belt: radiation use efficiency and grain yield Field Crops Res. 49 2/3 249 258 1997 WIDERS, I. E. The beans for health alliance: a public-private sector partnershipto support research on the nutritional and health attributes of beans. Ann. Rep. Bean Improv. Coop., v. 49, n. 1, p. 3-5, 2006. WIDERS I. E The beans for health alliance: a public-private sector partnershipto support research on the nutritional and health attributes of beans Ann. Rep. Bean Improv. Coop. 49 1 3 5 2006 WOOLLEY, B. L. et al. The critical period of weed control in white bean (Phaseolus vulgaris). Weed Sci., v. 41, n. 2, p. 180-184, 1993. WOOLLEY B. L. The critical period of weed control in white bean (Phaseolus vulgaris) Weed Sci. 41 2 180 184 1993