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To determine the suitable planting density and row spacing of short-season cotton suitable for machine picking in the Yellow River Basin of China, we conducted a two-year field experiment in Dezhou during 2018-2019. The experiment followed a split-plot design, with planting density (82500 plants ⋅ hm² and 112500 plants ⋅ hm²) as the main plots and row spacing (equal row spacing of 76 cm, wide-narrow row spacing of 66 cm+10 cm, equal row spacing of 60 cm) as the subplots. We examined the effects of planting density and row spacing on growth and development, canopy structure, seed cotton yield and fiber quality of short-season cotton. The results showed that plant height and LAI under high density treatment were significantly greater than those under low density treatment. The transmittance of the bottom layer was significantly lower than under low density treatment. Plant height under 76 cm equal row spacing was significantly higher than that under 60 cm equal row spacing, while that under wide-narrow row spacing (66 cm +10 cm) was significantly smaller than that under 60 cm equal row spacing in peak boiling stage. The effects of' row spacing on LAI varied between the two years, densities, and growth stages. On the whole, the LAI under the wide-narrow row spacing (66 cm+10 cm) was higher, with the curve declining gently after the peak, and it was higher than that in the two cases of equal row spacing in the harvest time. The change in transmittance of the bottom layer presented the opposite trend. Density, row spacing, and their interaction had significant effects on seed cotton yield and its components. In both years, seed cotton yield was the highest (3832 kg ⋅ hm² in 2018, 3235 kg ⋅ hm² in 2019) under wide-narrow row spacing (66 cm + 10 cm), and it was more stable at high densities. Fiber quality was less affected by density and row spacing. To sum up, the optimal density and row spacing of short-season cotton were as follows: density with 112500 plants ⋅ hm and wide-narrow row spacing (66 cm + 10 cm). [ABSTRACT FROM AUTHOR]

To exploit the difference of root nodule growth and nitrogen fixation potential of soybean in maize-soybean relay strip intercropping system, a two-year filed experiment with different nodulation characteristics soybean varieties (Gongxuan 1, Guixia 3, and Nandou 25) under different maize-soybean spacing (30, 45, 60, and 75 cm) was conducted. The results showed that the peaks of soybean nodule number and fresh weight were delayed under the intercropping system compared with soybean monoculture. The root nodule number and fresh weight of each variety under 60 cm were significantly higher than those of other spacing treatments, and were higher than those of monoculture soybean after reaching the peak stage. The differences among varieties were as follows: Nandou 25 > Guixia 3 > Gongxuan 1. Compared with soybean monoculture, nitrogen fixation potential of soybean nodules per plant before the beginning seed stage (R5) under intercropping mode was reduced. However, nitrogen fixation potential per plant of Gongxuan 1, Guixia 3, and Nandou 25 increased by 8.53%, 16.40%, and 13.70% on average in two years under 60 cm at R5 stage. The accumulation process of inclusions in infected cells of different soybean varieties was quite different. Compared with soybean monoculture, the number of bacteroids increased under 60 cm at R5, among which poly-P-hydroxybutyrate (PHB) increased, and Nandou 25 was the best. Therefore, to improve the number of soybean nodule bacteroids, PHB and nitrogen fixation potential the appropriate inter-plant row spacing (60 cm) under intercropping can increase soybean nodule number and fresh weight at R5 stage, and Nandou 25 with strong nodulation had the best effect. [ABSTRACT FROM AUTHOR]

Intercropping, by capitalizing on positive biodiversity–productivity relationships, represents a promising option to increase agricultural sustainability. However, the complexity and context-dependency of plant–plant interactions can make it challenging for farmers to find suitable crop combinations. Furthermore, intercropping is usually implemented with standard inter-row spacing and plant densities based on monoculture practices, which might not be the ideal configuration to maximize yield. Here we present a spatially-explicit yield analysis method based on plant ecological interaction models that allowed to optimize crop species combinations and spatial configurations for maximal yield in intercropped systems. We tested this method with three crop species, namely oat, lupine, and camelina. In a first step, field experiments in which crop density and adjacent crop type were varied provided us with indications on which species would compete more with each other. The results showed us that oat and camelina strongly competed with each other. In addition, the distance experiments allowed us to understand how the changes in yield associated with the presence of neighbors vary with distance. This allowed us to find the sets of parameters (identity of neighbors, sowing density, distances between individuals) that optimise intercrop yield (measured as Land Equivalent Ratio [LER]) for the three considered species. Specifically, we show that alternating rows of species led to higher LERs than a homogeneous species mixing, and that 3-species combinations are not necessarily more performant than the best 2-species combinations. In addition, we show that increasing the density of oat is generally beneficial for LER, while increasing the density of lupine is not. By modelling crop yield from simple and reproducible density and distance experiments, our results allow to optimize crop mixtures in terms of species combinations and spatial configurations, for maximal crop yield. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study was to determine the effects of 3 different row spacing (20 cm, 40 cm and 60 cm) and 3 seed quantities (1, 1.5 and 2 kg/da) on yield and some characteristics of phacelia for 2 years in the field of Gumushane University Gumushane Vocational School of Higher Education. The research was carried out in 3 replications according to the exact blocks trial pattern of chance during the season of breeding between 2014 and 2015. According to the results, row spacing plant height, number of flowers in the coal, green and dry grass yield, etc. B has a significant effect on traits. The highest values were obtained from plants planted in the range of 40 cm. These results show that it is appropriate to plant phacelia with a range of 40 cm and to use 1.5 kg/seed for grass production. [ABSTRACT FROM AUTHOR]

Soybean is a important source of protein and fat in the food and animal feed industries. Moreover, soybean also contains many other compounds, including minerals, which are beneficial for health and reduce the risk of many diseases. This study was conducted at the Czesławice Experimental Farm near Lublin (51°18'23°N, 22°16'02°E) in 2016. The soil on which the experiment was set up belongs to typical Luvisols. It was characterized by high phosphorus and potassium availability as well as very high magnesium availability. The aim of the present study was to determine the effect of cultivation (organic and conventional system) and row spacing (22.5 cm and 35 cm) on the level of minerals in seeds of two soybean varieties: Aldana and Merlin. The study was conducted using a split-plot design, in three replicates. Seeds were sown on May 5, whereas harvest was carried out on September 5, 2016. After seeds were harvested, the content of the following major minerals was determined in them: phosphorus, potassium, magnesium, calcium, molybdenum, manganese, copper and nickel. Variety Aldana seeds were characterized by a significantly higher content of potassium and copper, while in var. Merlin seeds the calcium concentration was higher. The contents of phosphorus, potassium, calcium, copper and nickel were found to be significantly higher in conventional system grown soybean seeds. Seeds of soybean grown at a row spacing of 22.5 cm contained more copper and nickel. Row spacing was not found to significantly affect the macronutrient content in the studied material. [ABSTRACT FROM AUTHOR]

Copyright of Arquivo Brasileiro de Medicina Veterinaria e Zootecnia is the property of Universidade Federal de Minas Gerais, Escola de Veterinaria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Exploiting the competitive ability of crops is essential to develop cost-effective and sustainable weed management practices. Reduced row spacing, increased seeding rates, and selection of competitive cultivars can potentially manage crop–weed competition in cotton, soybean, wheat, and corn. These cultural weed management practices facilitate a more rapid development of crop canopy that adversely affect the emergence, density, growth, biomass, and subsequently the seed production of weeds during a growing season. These cultural practices can also favour the weed suppressive ability of the crop by influencing the canopy architecture traits (plant height, canopy density, leaf area index, rate of leaf area development, and leaf distribution). These crop-competition attributes can potentially reduce the risk of crop yield losses due to interference from weed cohorts that escape an early- or a late-season post-emergence herbicide application. Furthermore, reduced row spacing, increased seeding rates, and weed-competitive cultivars are effective in reducing reliance on a single site-of-action herbicides, thereby reducing the selection pressure for development of herbicide-resistant weed populations in a cropping system. [ABSTRACT FROM AUTHOR]

Soybean ( Glycine max (L.) Merr.) is an important crop worldwide for both protein meal and vegetable oil. Soybean accounts for more than 50% of the global oilseed production. Weed infestation is a complex and regular threat to soybean production all over the world. To combat this threat, chemical, mechanical, and cultural methods are generally used. There has been a revived interest in weed suppression through improved crop competitiveness as an alternative aid in weed management. Different approaches could be utilized to increase crop competitiveness such as adjustment of row spacing, optimum seeding rate, and use of genotypes with high weed-competitive ability. During the past several decades, adoption of narrow row spacing has become increasingly popular among soybean growers primarily because of yield advantage and early canopy closure, which directly provides greater weed suppression. Adoption of narrow rows significantly reduces the density and biomass of late-season emerging weeds and delays the critical time for weed removal compared with wide rows. An increase in seeding density/plant population also suppresses weeds by earlier canopy closure, especially when combined with narrow row spacing. Competitive abilities of different soybean cultivars against different weed species are not consistent. Interseeding cover crops after establishment of soybean also can be a viable option for weed suppression as long as cover crops do not compete with soybean, or act as weeds themselves. Integrated weed management is considered to be the most effective approach for long-term and sustainable management of weeds in soybean. The objective of this article is to provide an overview of currently known cropping practices for improving soybean competitiveness against weeds. [ABSTRACT FROM AUTHOR]

The food security of many developing countries relies on sorghum production due to its low input requirements and ability to endure extreme climatic stresses. This C 4 grass species is widely cultivated for grain, feed/fodder, and bio-fuel uses in tropical and semi-arid areas of the world. A high efficiency water utilization mechanism and tolerance to drought and high temperatures favours it as an alternative crop to maize in areas with marginal water availability. Despite of its potential, this crop is underutilized given few weed management options. In addition to other biotic and abiotic factors, weeds are considered to be a major constraint, causing 15–97% losses for sorghum growth and yield under different climatic conditions. Previous studies where the crop spacing, seeding rate, and selection of competitive cultivars were altered, highlighted the importance of weed management through cultural practices or crop competition. Narrowing the crop rows and increasing plant densities were found effective in reducing the growth, biomass, and competitive ability of several weed species in sorghum. In addition, selection of competitive and allelopathic sorghum cultivars affected the weed seedling emergence by decreasing light interception and by releasing numerous allelochemicals. However, a review of the literature directed our attention towards some neglected points of weed management through crop competition in sorghum. For instance, crop row orientation has not been studied yet to investigate its influences on weed competitiveness against sorghum around the world. There is a dire need to diversify cultural practices in agro-ecosystems as much as possible to provide competitive advantage for the sorghum crop. Future research should be planned to evaluate the effectiveness of different sowing rates, dates, and directions on the crop yield and weed suppression under different cropping systems. Furthermore, cultural practices should be integrated with other weed management techniques for the development of a more reliable and sustainable weed control program in sorghum. [ABSTRACT FROM AUTHOR]

Adoption of conservation agriculture has brought significant changes in crop management in Australia. Increased reliance on herbicidal weed control is one of the most significant changes that have occurred throughout Australian cropping systems. The singular focus on herbicides for weed management has led to the frequent and widespread evolution of herbicide resistance in several weed species. Herbicide resistance means the loss of herbicide resources and as new herbicides modes of action are unlikely then use of alternative non-chemical cultural weed management options is essential. Crop competition is an approach that can be used to manage weeds for improved crop production. Enhanced crop competition can be achieved through the use of competitive crop species and cultivars, increased seed rates, narrow row spacing, and altered row orientation. These options are already routinely used in Australia and are proven in their ability to reduce weed biomass and fecundity. Although these strategies have been successfully used in Australian cropping systems, the research has frequently been focussed locally and not extrapolated more broadly throughout the Australian grain production region. Crop competition can potentially be a sustainable weed management option in reducing the reliance on herbicides and combating herbicide resistance and therefore, needs to be considered in all integrated weed management plans. [ABSTRACT FROM AUTHOR]

Agriculture occupies an important place in improving the living standards of farmers in Pakistan. About 90% of farm earnings rely on the cultivation of sugar, fibre, cereals and legumes. Due to lack of essential resources and technical expertise, every year thousands of farmers fail to reach maximum yield potential. Over 70% of farmers own less than 5 ha in Pakistan; therefore, it is uneconomic to employ costly mechanical and chemical strategies for the control of pests in their crops. Among these pests, we eds are considered to be the major obstacle to crop production, and can ultimately result in crop failure. Traditionally, manipulation of cropping techniques was employed for the control of weeds; later on, development of synthetic chemical herbicides made it easier to control weeds in a very short time period. However, over time the increased use of herbicides has led to the development of herbicide resistant weeds. Furthermore, increasing environmental concerns, weed population shifts, and increased managerial costs have made it difficult for farmers to control these weed species within their limited economic resources. Nowadays, scientists and research organizations are being urged to provide innovative weed management solutions, with minimal ecological impacts. Studies have revealed the importance of cultural strategies for the management of weeds in different cropping systems. Research has proved that alternation of cultural practices, and selection of competitive crop cultivars, could be a possible strategy to minimize the competitiveness of weeds. Increased crop densities, narrower row spacing, intercropping and alternation in row directions are among the weed control strategies gaining rapid attention in many countries. Unfortunately, limited information is available about weed management using crop competition in Pakistan. This review article focusses on the importance of these agronomic practices in reducing the competitive potential of weeds, for their effective and appropriate management in major crops of Pakistan. It is intended to assist researchers in the design of economically viable and eco-friendly weed management strategies, which will aid in eliminating the burden of herbicides and mechanical cultivation from farmer’s production costs. [ABSTRACT FROM AUTHOR]

Weeds are a major constraint to crop production, and are responsible for considerable yield losses in maize production systems throughout the world. Herbicides are widely used for weed control in maize production systems, but can have negative environmental consequences. Researchers have evaluated the use of crop competition and suppression to manage weeds in various crop combinations, including maize-based systems. Crop competition in maize may involve techniques such as reduced row spacing, increased planting density, and the use of competitive cultivars that exhibit weed suppressive potential. In this review, examination of the literature has revealed the considerable value of using crop competition in integrated weed management programs. Research has demonstrated that narrowing row spacing to half the standard distance reduced weed biomass by 39–68%, depending on weed species. Researchers have also demonstrated that increasing maize planting density by up to twice the standard rate achieved a reduction in weed biomass of 26–99%. While little research has been conducted into the use of competitive maize cultivars for weed management, several studies have documented cultivars with potential to suppress weeds. Attributes of weed competitive cultivars include high leaf area index, and other elements of leaf architecture that improve light interception by the crop, so increasing the shading of weeds. Combining crop competition methods with other agronomic practices can increase their effectiveness in controlling weeds. For example, biomass of Setaria italica (L.) Beauv was reduced by 60% when maize planting density was increased by 1.5 times the recommended spacing, and this effect was more pronounced when fertilizer was banded rather than broadcast. In summary, the strategic use of crop competition to control weeds has been a success in many regions, and is an important tool in integrated weed management. The importance of crop competition methods has particular relevance where farmers are unable to afford herbicides, as making use of crop competition is more economical. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the effect of the level of agronomic practice on the content of N, P, K, Mg, Zn, Cu, Mn, Fe and Ca in linseed seed cultivars (cv. Szafir and Oliwin) sown at a row spacing of 15 cm or 25 cm. A field experiment was carried out in 2010-2012. on mixed rendzina soil. The agronomic practice applied differed in the dosage of nitrogen (40, 60 or 80 kg N ha-1) and in weed control (A - without herbicides; B - with two herbicides, C - with three herbicides). The cultivar Szafir was characterised by a significantly higher content of nitrogen than cv. Oliwin, which in turn had a higher manganese content. The content of potassium, magnesium, zinc and manganese in seeds was higher when flax was sown at the narrower row spacing (15 cm) compared to the 25 cm row spacing. A similar relationship was determined for nitrogen, iron and calcium, but statistical verification did not confirm the significance of these differences. The level of agrotechnology in linseed crop cultivation did not influence the seed concentration of the elements. A slightly higher content of the elements in seeds was detected in the treatments where extensive (40 kg N ha-1, without herbicides) and medium intensive technology (60 kg N ha-1, Linurex 50 WP, Fusilade Forte 150 EC) were used, compared to intensive technology (80 N ha-1, Linurex 50 WP, Fusilade Forte 150 EC, Glean 75 WG). A slightly higher content of Fe and Ca was determined in seeds harvested from the plots where the intensive technology was used. Weather conditions significantly affected the content of K, Mg, Zn and Mn in linseed seeds. [ABSTRACT FROM AUTHOR]

Field experiments were conducted at the University farm of the University of Education, Winneba, Mampong-Ashanti Campus, Ghana, during the major rainy seasons of 2010 and 2011 to evaluate the growth, yield and productivity of a maize varietal intercropping system as influenced by relative times of planting (RTP) and row spacing. Three relative times of planting [(i) simultaneous, (ii) early-maturing maize (Akposoe) planted 10 days before medium-maturing maize (Obatanpa) and (iii) medium-maturing maize (Obatanpa) planted 10 days before early-maturing maize (Akposoe) were combined with two row spacings [(i) 80 cm and (ii) 100 cm] in a 3 x 2 factorial arranged in a randomized complete block design with three replications. Sole Akposoe and Obatanpa were included as checks and to compare the productivity of the varietal intercrop options with the sole crops. The relative times of planting, row spacing and their interaction did not significantly influence the days to 50% tasselling (DFT) and days to 50% silking (DFS) of both maize varieties in both seasons. In both seasons, the plant height and total dry matter (TDM) accumulation of sole Akposoe and Obatanpa were greater than when both were intercropped. Among the intercrops, the plant height and TDM accumulation of both varieties when planted simultaneously were similar to when planted 10 days before the other, but greater than when delayed 10 days, for both seasons. Akposoe and Obatanpa intercrops spaced at 80 cm row spacing produced higher plant height and TDM accumulation than the 100 cm row spaced plants in both years. The sole Akposoe and Obatanpa out-yielded their intercropped counterparts by 12-53% in both seasons. For the intercrops, the grain yield of Akposoe planted simultaneously with Obatanpa (1.71-2.12 t/ha) was similar to Akposoe planted 10 days before (DB) Obatanpa (1.80-2.20 t/ha), but out-yielded Akposoe planted 10 days after (DA) Obatanpa by 5-28% in both seasons. The grain yield of Obatanpa planted simultaneously with Akposoe (3.38-4.78 t/ha) were also similar to the grain yield of Obatanpa planted 10 days before Akposoe (3.28-3.83 t/ha), but were 4-41% greater than the yield of Obatanpa planted 10 days after Akposoe in 2010 and 2011. The 80 cm row spacing yielded 8-24% and 11-26% in 2010 and 2011, respectively, higher than the 100 cm row spacing. The varietal intercrops had higher productivity or land use ratios (1.12-1.76 for RTP and 1.14-1.80 for row spacing); and therefore, were 12-80% more productive and biologically more efficient than the sole crops in both seasons. Maize varietal intercropping produced higher total yield and was more productive under rain-fed conditions. [ABSTRACT FROM AUTHOR]

The yield of achenes and the yield components of the head are specific to each sunflower hybrid, but they are influenced by the different growing factors (environmental and technological factors). Soil and climatic conditions are among the environmental factors with a great influence on the sunflower yield. Row spacing and plant population are of great importance among the technological factors. In this respect, the present study was aimed to study the influence of row spacing and plant population on yield of achenes and yield components of the head under different soil and climatic conditions from South Romania. Researches were performed in field experiments in the years 2013 and 2014, in two locations from South Romania, respectively Fundulea (44 o 28’ N latitude and 26 o 27’ E longitude) and Moara Domneasca (44 o 29’ N latitude and 26 o 15’ E longitude). In each location and experimental year there were studied four sunflower hybrids (Pro 111, Pro 953, LG56.62, and P64LE19), each of them under three row spacing (75 cm, 50 cm, and twin-rows of 75/45 cm) and under three plant populations (50,000, 60,000, and 70,000 plants ha -1 ). The row spacing influenced differently the yield components of sunflower head according to the soil and climatic conditions. The highest yields were obtained at row spacing of 75 cm under favourable growing conditions and at row spacing of 50 cm under less favourable growing conditions. The increasing of plant population from 50,000 to 60,000 and further to 70,000 plants ha -1 decreased the values of yield components of the head. In the same time, the increasing of plant population increased the yield under favourable growing conditions and decreased the yield under less favourable growing conditions. [ABSTRACT FROM AUTHOR]

In the North Western Coastal Zone (NWCZ) of Egypt, low rainfall results in poor crop production. Different techniques should be examined to enhance the crop yield productivity and increase the water use efficiency. The ridge–furrow water harvesting system (RFWHS) is examined under the rainfed conditions in the NWCZ of Egypt over the two growing seasons of 2012/2013 and 2013/2014. Two ridge:furrow ratios of 120:60 and 60:60 cm ridge:furrow were used and compared to the conventional cultivation in a flat plot. The RFWHS was combined with different plant densities produced from three different row spacing (i.e., 20, 30, 60 cm). The faba bean yield was highly influenced by the ridge:furrow ratio, the seed yield was increased by 47% and 128.2% when the 60:60 cm ridge:furrow ratio was used as compared to the conventional cultivation in the first and second seasons, respectively. The row spacing of 30 cm apart produced the highest seed yield of 491.1 kg/ha in the first season and 261.3 kg/ha in the second season as compared to 20 cm and 60 cm row spacing. The water use efficiency followed the same pattern as that of seed yield; it was the highest for the 60:60 cm ridge:furrow ratio and the highest for the 30 cm row spacing. It is concluded that the RFWHS can be used effectively in increasing faba bean production and maximizing water use efficiency in limited rainfall areas. [ABSTRACT FROM AUTHOR]

Reducing crop row spacing and delaying time of weed emergence may provide crops a competitive edge over weeds. Field experiments were conducted to evaluate the effects of crop row spacing (11, 15, and 23-cm) and weed emergence time (0, 20, 35, 45, 55, and 60 days after wheat emergence; DAWE) on Galium aparine and Lepidium sativum growth and wheat yield losses. Season-long weed-free and crop-free treatments were also established to compare wheat yield and weed growth, respectively. Row spacing and weed emergence time significantly affected the growth of both weed species and wheat grain yields. For both weed species, the maximum plant height, shoot biomass, and seed production were observed in the crop-free plots, and delayed emergence decreased these variables. In weed–crop competition plots, maximum weed growth was observed when weeds emerged simultaneously with the crop in rows spaced 23-cm apart. Less growth of both weed species was observed in narrow row spacing (11-cm) of wheat as compared with wider rows (15 and 23-cm). These weed species produced less than 5 seeds plant −1 in 11-cm wheat rows when they emerged at 60 DAWE. Presence of weeds in the crop especially at early stages was devastating for wheat yields. Therefore, maximum grain yield (4.91 t ha −1 ) was recorded in the weed-free treatment at 11-cm row spacing. Delay in time of weed emergence and narrow row spacing reduced weed growth and seed production and enhanced wheat grain yield, suggesting that these strategies could contribute to weed management in wheat. [ABSTRACT FROM AUTHOR]

In a field experiment conducted in 2005-2007 on light soil, medium-tall leafy field pea (Pisum sativum L.) cultivar Wiato (dry seed type) and tall leafy pea cultivar Fidelia (green forage/dry seed type) were grown in two-species mixtures with spring barley (Hordeum vulgare L.). The aim of the research was to assess the effect of partial separation of the components in the intercrop on barley-pea interaction, canopy lodging, biomass yield and grain production. The species were sown in intercrops using separate passes of the seeder in the same direction, with pea seeded first in regular row spacing of 10.8 cm. The partial species separation was achieved through sowing barley in four different row arrangements in the intercrop: uniform row spacing of 10.8 and 21.6 cm, and alternate row spacing of 10.8/32.4 cm and 10.8/43.2 cm. The intercrop with barley seeded in rows spaced 10.8 cm apart and that with alternate row spacing of 10.8/43.2 cm yielded the same grain during the experimental years. Compared to those, the mixture with alternate 10.8/32.4 cm row spacing of barley yielded significantly less grain in 2005 and 2006. [ABSTRACT FROM AUTHOR]

Narrow row planting has potential to increase crop growth and yield by increasing radiation interception (RI) and minimizing intra-specific competition in the crop. It reduces weed growth and competitiveness, making resources that are normally taken up by weeds available for crop uptake. The objective of this study was to assess the effect of row spacing on weed biomass, bean growth and yield in a semi arid agro-ecology at Nyagatare, Rwanda. The study was set up as a randomized complete block design in October-December 2009 and repeated in 2011. Planting patterns at a constant bean population density of 111 000 plants ha−1 random planting (normal practice), narrow row planting (30 cm × 30 cm), medium row planting (45 cm × 20 cm) and wide row planting (60 cm × 15 cm) were treatments tested in this study. The narrow row square planting pattern significantly (P < 0.01) out-yielded the wide and random planting patterns by 22-31% in the wet 2009 season and by 27-70% in the dry 2011 season. Bean plant dry weight (P < 0.01) and number of pods per plant (P < 0.01) was highest in the narrow row and lowest in the random planting pattern in the dry 2011 season. Bean plant dry weight was not significantly affected (P > 0.05) in the wet 2009 season but number of pods plant−1 (P < 0.001) was highest in the narrow row and lowest in the random planting pattern. Weed biomass was significantly lower (P < 0.05) in the narrow row and the random than in the medium and wide row planting patterns at 3, 6 and 9 weeks after emergence in 2009, but the random planting had the highest weed biomass in 2011. The results suggest that the effects narrow row planting in alleviating the negative impact of inter- and intra-specific competition were more strongly expressed in the dry 2011 season than the wet 2009 season when water was probably not a limiting factor to crop growth and yield. The results also indicate that narrow and equidistant planting has potential to increase bean yield by 30%-70%, when compared to random planting (normal practice) while at the same time suppressing weed growth and is recommended for smallholder farmers in Rwanda and other semi-arid areas in sub-Saharan Africa. [ABSTRACT FROM AUTHOR]

Copyright of Revista Ciência Agronômica is the property of Revista Ciencia Agronomica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Ciência Agronômica is the property of Revista Ciencia Agronomica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Field experiments were carried out during rainy seasons of 2001 and 2002 to study the effect of row spacing, plant density, and weed control method on plant growth, nutrient uptake, and economics in no-till maize in the Indo-Gangetic plains of India. Narrow spacing (45 cm) and high plant density (90,000 plants ha-') gave significantly higher leaf area index, dry matter accumulation, N, P, and K uptake and net return per unit investment. Highest leaf area index, DM accumulation, nutrient uptake, and net return were observed under paraquat application at 0.75 kg active ingredient (ai) ha-1 at 30 days after sowing, that was statistically similar to two hand weedings. Narrow spacing and higher plant density with either paraquat application at 0.75 kg ai ha-1 or two hand weedings provided better plant growth, nutrient uptake, protein content, and economics under no-till conditions. [ABSTRACT FROM AUTHOR]