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Background: Peanut yields are affected by plant density and chemical controls. Methods: A field experiment was conducted in Southern China to investigate the effects of population density and paclobutrazol applications on the growth and yield of peanuts with monoseeding and double seeding patterns. Result: Paclobutrazol application could improve peanut yields. The highest peanut yields were observed with 250 mg L-1 paclobutrazol and a plant density of 235 410 plants ha-1, with the monoseeding pattern. Our results suggest that monoseeding and paclobutrazol could be applied to enhance peanut yields in Southern China. [ABSTRACT FROM AUTHOR]

Camelina (Camelina sativa L. Crantz), has gained considerable attention in Europe as a potential oil seed feedstock for biofuels and bioproducts, although as cultivated surfaces it remains a marginal crop. As well in Romania progress has been made towards camelina's yield potential but this under organic agriculture conditions has not been studied enough. Given this increased interest in camelina, six genotypes were compared to characterize camelina's production potential in organic farming. Field experiments were conducted out in a randomized complete block design (RCBD) with four replications, six genotypes in three growing seasons (2016-2019). Plant population, frequency (F%) of downy mildew attack, weeds infestation and yield were evaluated. The higher amount of spring rainfall (in 2017 and 2019) and cooler temperatures favoured a significant downy mildew plant infection, with some variations among genotypes. GP 202 proved to be most sensitive to downy mildew attack followed by Lena. The most resistant genotype was Calena, which recorded, for the three different years, the lowest degree of attack. In weeds suppression the variation due to year was higher than that due to the genotype and interactions of the factors. Results identify, in relation to climatic conditions, the most suitable genotypes for the tested environment, in terms of resistance to downy mildew and weed infestation. Calena, Camelia and Lindo genotypes were more less affected by downy mildew, weed infestation was less and the yield was higher as compared to the other genotypes studied. [ABSTRACT FROM AUTHOR]

The field experiments were conducted at Indonesian Vegetable Research Institute (IVEGRI) West Java, Indonesia during the period of July 2018 to February 2019. The objective of the study was to determine the effect of three plant densities (20,000, 30,000 and 40,000 plants ha-1 ) and four stem pruning levels (control, 3 stems, 4 stems, and shoot pruning) on growth and yield parameters as well as pest and diseases incidences for chili pepper. Split plot experiment was performed using a randomized block design with three replications. The recommended cultural practices were done for better crop growth and good yields. Results showed no interactions between plant density and pruning for any of the variables measured. Chili pepper growth, yield, and quality and incidence of pest and diseases can be effectively manipulated by plant density and pruning. Increasing of plant population from 20,000 to 30,000 plants ha1 resulted in the increased of total fruit yield to 52.58%, however, total fruit yield declined up to 34.09% at 40,000 plant/ha. Pruning significantly affected fruit yield from 4.65 to 20.33%. Shoot pruning produced higher number of branches, and resulted in maximum yield per ha-1 due to higher number of shoots contributing to the production of more number of fruits. Growing chili pepper at a density of 30,000 plant ha-1 was better than the conventional methods, and it combination with shoot pruning in nurseries could be used as an alternative method to increase the production of chili pepper. [ABSTRACT FROM AUTHOR]

ABSTRACT The automatic control of section shut-off in seed drills minimizes seeding overlap and can reduce productivity losses, especially in responsive crops such as corn. In that context, this study evaluated the effect of sowing overlap on the grain yield and productivity of three corn hybrids. A DB-50 precision seed drill, with 33 rows equipped with a 16-row automatic section control, was used in this experiment. A randomized block design was applied to test three corn hybrids under two sowing conditions (without sowing overlap - WOSO; and with sowing overlap - WSO), with four replications. The analyzed variables were the number of plants per hectare, the number of cobs per hectare, cob length, the number of grains per cob, the thousand grain weight, and productivity. WOSO areas presented cobs that were larger and had more grains, as well as a higher thousand grain weight, resulting in a productivity 13% higher than that of WSO areas. Therefore, the use of automatic section control is a technically feasible alternative to reduce seed costs and avoid productivity losses in corn crops.

Chickpea (Cicer arietinum L.) is commonly grown under dryland conditions during spring on soils that conserve moisture from the preceding season, in Iran. Seeding rate can have a major impact on production of chickpea. A field trial was carried out at Gerizeh Agricultural Research Station of Kurdistan (35°16’N 47°1’E), west of Iran during 2015-16 cropping season. The trial was carried out in a factorial experiment based on randomized complete block design (RCBD) with three replications. The factor "A" was plant densities, consisting of 15, 25, 35, and 45 plants m-2 and factor "B" was chickpea varieties (Kaka, Pirouz, ILC 482, and Samin). The effect of chickpea varieties and interaction between plant densities and varieties were significant on all measured parameters, except on number of seed per pod, plant height and height of first pod. Also, the effects of plant densities on seed yield, 100 seed weight, leaf chlorophyll index, protein content, plant height, and number of branch per plant were also significant. Results showed that an increase in plant density resulted in significantly higher seed yield per hectare. The mean yields indicated the sensitivity of "Samin" cultivar to high plant population, while it was, suitabilie to cultivar "ILC482" (45 plants m2). "Kaka" and "Pirouz" produce near optimum yields at medium plant densities (25 and 35 plants m-2). Mean yield comparison of cultivar × palnt density showed that cultivars "Pirouz", "ILC482" and "Samin" did not differ significantly in protein content but "Kaka" significantly produced higher protein content the three cultivars. Correlation coefficient for seed yield, number of pods/plant, seed weight, number of branch/ plant and plant height were positive and significant, while for seed yield, and height of first pod were negative and significant. According to the results of the this study Samin, with its large seed size and other desirable characteristics and plant population of 35 plants m-2 can be recommended for planting in Sanandaj and similar climatic areas.

The biogas supply chain requires a correct combination of crops to maximize the methane yield per hectare. Field trials were carried out in North Italy over three growing seasons, according to a factorial combination of four cropping systems (maize as a sole-crop or after hybrid barley, triticale and wheat) and two maize plant densities (standard, 7.5 plants m−2 and high, 10 plants m−2) with the plants harvested as whole-crop silage. The specific methane production per ton was measured through the biochemical methane potential (BMP) method, while the methane yield per hectare was calculated on the basis of the BMP results and considering the biomass yield. The average methane yield of wheat resulted to be equal to 4550 Nm3 ha−1, and +17% and +28% higher than triticale and barley, respectively, according to the biomass yield. A delay in maize sowing reduced the yield potential of this crop; the biomass of maize grown after barley, triticale and wheat was 20%, 33% and 47% lower, respectively, than maize cultivated as a single crop. The high plant population increased the biomass yield in the sole-crop maize (+23%) and in the maize grown after barley (+20%), compared to the standard density. The highest biomass (32 t ha−1 DM) and methane yield (9971 Nm3 ha−1) within the cropping systems were obtained for barley followed by maize at a high plant density. This cropping system increased the methane yield by 46% and 18%, respectively, compared to the sole-crop maize or maize after triticale at a standard density. The smaller amount of available solar radiation, resulting from the later sowing of maize, reduced the advantage related to the application of a high plant density.

The banana (Musa AAA Simmonds) is one of the most consumed fruits in the world, due to its contribution of potassium, vitamins and nutrients for human beings. The social contribution of this cultivation system in the producing areas of the world and Colombia is remarkable for the generation of jobs and economic income for the region. In Urabá Antioquia and the department of Magdalena, fruit shortages occur every year in the first semester and an oversupply in the second semester, motivated by low or high precipitation respectively, a situation that affects the value of production. On the other hand, the cultivation system in low densities (populations less than 2000 plants ha-1) its deterioration is evident as the vegetative cycles pass because of loss of anchoring of the plants due to their habit of natural growth, the emission of children to the surface of the soil that generate blurring of the corms or rhizome of the plants and the problems of pests, poor drainage among other factors that affect the roots and negatively influence the productivity and quality of fruit. Given this situation, it is necessary to develop agronomic management strategies that contribute to improve productivity and offer alternatives to reduce the impacts of seasonality of the climate on the production of this fruit in Colombia. In this sense, the establishment of banana crops under high density sowing (HDP) is a management practice that in addition to optimizing the use of natural resources, also allows to increase productivity without affecting the quality of the fruit. Currently, the research generated in order to characterize this practice of cultivation in HDP, has allowed to estimate the parameters of growth, development, Eco physiological, production and post-harvest as a suitable tool for the design of these crop systems in order to contribute positively to the increase in the production and quality of fruits. However, there is still a need to generate more awareness in both the professionals and producers involved in these cultivation systems in the proper implementation of these crop systems in HDP in order to make a rational use of natural resources, in addition to continuing with the relevant adjustments of this agronomic practice. Therefore, the purpose of the presentation is to analyze the parameters established in HDP as a strategy to optimize the cropping system. [ABSTRACT FROM AUTHOR]

Coffee tree density optimization can improve fortunes of stakeholders, especially smallholder farmers who dominate the sub-sector at production level. An attractive example is with highly productive countries where high plant densities do increase area yield but across board recommendations are illogical especially with variety and agroecological variations. We aimed to compare two spacing regimes for growth response and pest incidence using Uganda’s unique C. canephora. Randomized complete block designs with three replications and eight plants per plot were established at four locations. Eleven growth variables namely stem girth (STG), number of internodes on stem, plant height (PH), canopy height, canopy diameter, number of primaries, number of active bearing primaries, length of longest primary (LLP), number of internodes on primary, leaf blade length and leaf blade width (LBW) were measured. Incidences of black coffee twig borer (BCTB), leaf eating beetles (LEB), leaf miners (LM), skeletonizers (SKL) and tailed caterpillars (TC) were also assessed. Highly significant differences between spacing regimes (p

Studies addressing the interaction of different spatial arrangement in soybean are needed in order to achieve management that leads to higher grain yield associated with rational seed use. The objective of this work was to evaluate the yield components and productivity of an undetermined growth type soybean as a function of different row spacing and plant densities. The treatments consisted of three row spaces (0.25, 0.35 and 0.45 m) and three plant population densities (30, 40 and 50 plants/m²). There was no interaction of row spaces and plant population on soybean yield. Regarding the overall spacing average, the grain yield of the population of 30/m² plants was higher than the productivity of the populations of 40 and 50/m² plants. The largest populations reduce plant sizes due to greater competition between plants. In addition, smaller populations promote higher individual plant yields due to the increase components of the production. This characteristic is defined as the ability of the plant to change its morphology and yield components in order to adapt to the conditions imposed by the spatial arrangement.

Coffea canephora has non-limiting but unexploited yield and quality potential when compared with C. arabica. Coffee tree density optimization can improve fortunes of smallholder farmers. An attractive example is that high productive countries where high plant densities do increase area yield but across board recommendations are illogical especially with variety and agroecological variations. We aimed to compare two spacing regimes for growth response and pest incidence using Kituza Robusta clone. Randomized complete block designs with three replications and eight plants per plot were established at four agroecologically diverse on-farm locations. Eleven plant growth variables were measured. In addition incidences of five key pests were assessed. Data was collected on a 3-month interval starting from 12 up to 21 months after planting. Highly significant differences between spacing regimes (p

Increases in plant density associated with the use of plant growth regulators, aside from modifying the plant architecture, can also change the maize yield performance. This study aims to investigate the yield components and grain yield of maize hybrids with contrasting leaf architecture, in response to different plant populations and trinexapacethyl rates (TE). Field experiments were conducted in two growing seasons, in a (5 x 5) factorial randomized block design. The treatments consisted of: five plant population (40, 60, 80, 100, and 120 thousand plants ha-1) and five TE rates (0, 100, 200, 300, and 400 g a.i. ha-1), with four replications, using the hybrids 2B710 HX and Status TL. We evaluated the number of rows per ear, ear length, number of grains per row, 1000-grain mass, and yield. An increased plant density reduces ear length, number of grains per row and 1000-grain mass, without changing the number of grain rows per ear. TE rates increases ear length and number of grains per row and reduces 1000-grain mass, mainly under favorable cultivation conditions. TE interacts with the plant density, changing the maize yield components with increases in grain yield, but these gains variy, according to the environment and genotype characteristics. [ABSTRACT FROM AUTHOR]

The study of the structure and dynamics of vegetation was carried out in the ecosystems of southern Benoue in northern Cameroon. The general objective of this work is to characterize the structure of the vegetation and to assess the degradation of the ecosystems. The inventory methods chosen include biodiversity survey techniques commonly used in ecological studies. A total of 36 100 m x 100 m quadrat plots were established in four plant formation: reserve, forest gallery, field and anthropized savanna to take dendrometric parameters such as size, diameter at breast height of all woody species. Landsat satellite images were processed and analyzed between 1989 and 2019 using Google Earth and GIS software, QGIS 10.12.1.The vegetation presents a physiognomy of open forest with a diametral L-shaped structure reflecting the dominance of individuals of small DBH and a vertical "U" structure reversed from sites and plant formations reflecting a low representation of juvenile and adult individuals. As for the diachronic study by remote sensing, it emerges from the variations of land use elements an increase in field (by 29%, 10% and 20%), of the grassy savannah (by 2%, 14% and 8 %) and buildings and bare soil (by 5%, 8% and 2%) and a decrease in shrub savannah (by -31%, -23% and -14%), in wooded savannah (by -2%), -5% and -12%) and gallery forest (-4%, -5% and -4%) respectively for Garoua 3, Lagdo and Ngong. Overall, our zone is marked by an accentuated state of degradation of the vegetation with a current state of cover of the grassy savanna of 38%, of the field of 28%, of the shrub savannah of 16%, of the wooded savanna and the frame and bare floors of 7% each, the forest gallery of 5% and the open water of 4%.These results open up better prospects for the development of planning and development mechanisms of this area not yet deeply explored for the bases of a good management strategy. [ABSTRACT FROM AUTHOR]

The paper considers indicators of the dynamics of plant communities with Paeonia tenuifolia before and after fire impact. Studies were conducted in the Khvalynsky National Park (forest-steppe zone of Russia) in 2008–2018. The authors conducted a complex study in burned and unburned plant communities. An assessment of the effects of fire impact and the development of a post-fire action plan were considered in the Protected Area. The plant community Paeonia tenuifolia + Calamagrostis epigejos + Adonis vernalis – Potentilla volgarica burned down in 2009. The plant community Paeonia tenuifolia + Stipa pennata + Adonis vernalis – Anemone sylvestris was unburned. To characterise plant communities with Paeonia tenuifolia and its coenopopulations, we used standard geobotanical description methods. Sixty seven vascular plant species were part of the post-fire phytocoenosis. Of them, 14 species are included in the Red Data Book of the Saratov region. Changes in the post-fire plant community have occurred in the following order: 1) Paeonia tenuifolia + Calamagrostis epigejos + Adonis vernalis – Stipa pennata (in 2008) → 2) Paeonia tenuifolia + Elymus repens + Stipa pennata + Adonis vernalis + Thalictrum simplex (in 2010) → 3) Paeonia tenuifolia – Stipa pennata – Calamagrostis epigejos + Festuca valesiaca +Phleum pratense + Poa bulbosa + Prunus tenella (in 2011) → 4) Paeonia tenuifolia + Adonis vernalis + Stipa pennata (in 2015, 2017, 2018). After the fire influence on a plant community, the following changes took place: 1) annuals and ruderal plant species appeared and increased their abundance; 2) the ratio of dominant species has changed. In 2012–2018, the phytocenotic role of Calamagrostis epigejos decreased, while the coverage and abundance of Stipa pennata increased at the same period. The abundance dynamics of Paeonia tenuifolia decreased in 2010, while in 2015–2018, its value gradually increased. The species richness of the post-pyrogenic plant community varied from 20 species in the first post-fire year to 38 species in the last study year. In the first post-fire year, the families Poaceae (six species), Leguminosae plants (three species), Rosaceae plants (three species) occupied the leading positions. During the post-pyrogenic succession, the dominant position of the listed families was not changing. Species of Compositae, Poaceae, Ranunculaceae families prevailed in the unburned plant community. Steppe plants dominated in the post-fire plant community: Stipa pennata, Adonis vernalis, and Paeonia tenuifolia. The leading ecologic-coenotic groups were steppe plants (70%), meadow plants (16%), forest plants (5%), and ruderal plants (9%). Weed-steppe plants were indicators of habitat disturbance by human activities. Among weed-steppe plants, there were Arenaria serpyllifolia, Viola rupestris, Erysimum canescens, Verbascum lychnitis. Gradient analysis of environmental conditions showed that the highest value of the vitality index (IVC = 1.15) corresponds to the best conditions for the growth and survival of the Paeonia tenuifolia population in the post-fire community. In the control site, the vitality index (IVC = 0.85) corresponded to unfavourable conditions for plant development. We studied the age spectra of the natural Paeonia tenuifolia populations in the burned and unburned communities. We showed that both populations were normal, complete, and young. The fire-damaged populations were younger than the populations in the unburned communities. We suggest the need of comprehensive monitoring studies to properly assess the fire effects and subsequent management actions for the vegetation restoration after fire influence.

Farmers in Bangladesh are always seeking an optimal seed rate to reduce production costs and increase wheat yield. The Wheat Research Centre (WRC) of Bangladesh has developed new wheat varieties over several years. To reduce production costs and obtain higher grain yield (GY) from these varieties, optimum seeding rates are needed. In this context, a two-year field experiment was conducted with five newly released wheat varieties (‘BARI Gom 24’, ‘BARI Gom 25’, ‘BARI Gom 26’, ‘BARI Gom 27’ and ‘BARI Gom 28’) and three seeding rates (100, 120 and 140 kg ha─1). These treatments were performed under irrigation in the WRC research field in Northern Bangladesh to determine the optimum seeding rates for these varieties. Significantly higher GY (p≤0.05) was obtained with a seeding rate of 140 kg ha─1 for all varieties, compared to other rates. A seeding rate less than the recommended rate (120 kg ha─1) for all varieties failed to produce comparable GY in both years. Among all varieties, ‘BARI Gom 26’ had the highest GY while ‘BARI Gom 25’ had the lowest GY in both years. Although the interaction effect of variety and seeding rate on GY did not vary significantly (p≤0.05) in both years, surplus GY was 467 and 233 kg ha─1, respectively for ‘BARI Gom 24’, 63 and 75 kg ha─1 for ‘BARI Gom 25’, 81 and 93 kg ha─1 for ‘BARI Gom 26’, 23 and 66 kg ha─1 for ‘BARI Gom 27’, and 152 and 220 kg ha─1 for ‘BARI Gom 28’ in the first and second year when seeded at 140 kg ha─1. For the same seed rate, the GY of ‘BARI Gom 24’ increased by 5.3 to 9.6% and that of ‘BARI Gom 28’ increased from 2.8 to 5% over the two years. Therefore, a seeding rate of 140 kg seed ha─1 is recommended for ‘BARI Gom 24’ and ‘BARI Gom 28’, while the current recommended rate (120 kg ha─1) should be continued for the other three varieties when grown under irrigation on the Old Himalayan Piedmont Plain of Bangladesh.

Banana is after apple, the most consumed fruit in the world for its nutritional contribution. Given its importance, it is necessary to advance in the development of agronomic management strategies that contribute to increase productivity and offer alternatives to regulate the consequences derived from the seasonality of production in the Urabá area (Colombia). For this, the clone Williams (Musa AAA Simmonds), at different planting densities (2000, 2500, 3000 and 3500 plants ha-1), different population arrangements (triangle, rectangle and double furrow), compared with a relative control (1700 plants ha-1 in triangle) was evaluated. The design used was randomized complete blocks in factorial arrangement of 4 x 3 + 1 (densities x arrays + control). The variables height and perimeter of the pseudostem, number of leaves from planting to harvest, leaf area index (IAF), light extinction coefficient, number of suckers and developmental stages (days elapsed after flowering and harvest) were determined. An analysis of general variance was carried out and another one excluding the control. The Tukey test (P

Carrots (Daucus carota L. var sativus) in the midwestern United States are generally raised commercially on sandy-loam or muck soils. Some smaller growers may not have the luxury of an ideal soil type, so raised beds are often recommended to improve taproot growth. To determine specific yield and shape responses of carrots to raised-bed culture in heavy soil, three hybrids (‘Cupar’, ‘Envy’, and ‘Naval’) were grown in 2019 and 2020 on raised or flat beds in clay-loam soil. In addition, two seeding rates (high or low) were incorporated into the split-split plot design. ‘Cupar’ was larger and less misshapen than the other hybrids, but total marketable yields were similar among all three. ‘Naval’ was the most cylindrical. High seeding rate generally resulted in more numerous but smaller marketable roots and no change in total marketable weight. Raised beds caused a 10.6% increase in total marketable weight by allowing more marketable roots classified as “short” (between 76 and 127 mm long, diameter >25 mm) to grow to lengths more than 127 mm long. The average taproot cylindricity was increased and diameter decreased by growing on raised beds. Soil penetration resistance at 7.6 cm was correlated with many of the measured responses. [ABSTRACT FROM AUTHOR]

Abstract: Initial seed vigor and sowing density interact in establishment of plants in the field, and can thus affect expression of the plasticity of the wheat crop and the yield and physiological quality of the seeds produced. The aim of this study was to evaluate the effect of seed vigor levels in combination with sowing densities on the yield and physiological potential of wheat seeds. The cultivars BRS Gralha-Azul and BRS Sabiá were used in a randomized block experimental design in a 2 × 4 factorial arrangement, with four replications. The treatments consisted of seeds of high and low vigor and four sowing densities (150, 250, 350, and 450 seeds.m-2). The following evaluations were made: seed yield, germination, first germination count, seedling length, seedling dry matter, accelerated aging, emergence speed index, and seedling emergence in sand. An increase in sowing density favors the seed yield of both cultivars; however, it reduces the vigor of the seeds produced by the cultivar BRS Gralha-Azul, especially of the seeds produced by plants originating from high vigor seeds. For the cultivar BRS Sabiá, an increase in sowing density decreases the germination performance of seeds produced by plants originating from low vigor seeds.

[Display omitted] • Polyploidization events were the main driving force for GRASs expansion. • Evolutionary analysis reveals that inter-species GRASs functions may be conserved. • GRASs helped plants resist stress by regulating flavonoids pathway. • GRASs regulate flavonoid synthesis by crosstalk with auxin and photosynthetic pathway. • Polyploidized GRASs play key roles in environment adaption, growth and development. Environmental stress is both a major force of natural selection and a prime factor affecting crop qualities and yields. The impact of the GRAS [gibberellic acid-insensitive (GAI), repressor of GA1–3 mutant (RGA), and scarecrow (SCR)] family on plant development and the potential to resist environmental stress needs much emphasis. This study aims to investigate the evolution, expansion, and adaptive mechanisms of GRASs of important representative plants during polyploidization. We explored the evolutionary characteristics of GRASs in 15 representative plant species by systematic biological analysis of the genome, transcriptome, metabolite, protein complex map and phenotype. The GRAS family was systematically identified from 15 representative plant species of scientific and agricultural importance. The detection of gene duplication types of GRASs in all species showed that the widespread expansion of GRASs in these species was mainly contributed by polyploidization events. Evolutionary analysis reveals that most species experience independent genome-wide duplication (WGD) events and that interspecies GRAS functions may be broadly conserved. Polyploidy-related Chenopodium quinoa GRASs (CqGRASs) and Arabidopsis thaliana GRASs (AtGRASs) formed robust networks with flavonoid pathways by crosstalk with auxin and photosynthetic pathways. Furthermore, Arabidopsis thaliana population transcriptomes and the 1000 Plants (OneKP) project confirmed that GRASs are components of flavonoid biosynthesis, which enables plants to adapt to the environment by promoting flavonoid accumulation. More importantly, the GRASs of important species that may potentially improve important agronomic traits were mapped through TAIR and RARGE-II publicly available phenotypic data. Determining protein interactions and target genes contributes to determining GRAS functions. The results of this study suggest that polyploidy-related GRASs in multiple species may be a target for improving plant growth, development, and environmental adaptation. [ABSTRACT FROM AUTHOR]

Plastic mulches have been extensively used in tomato fields around the world; its use has been growing in Brazil, especially in semi-arid regions. However, whether plastic mulches are beneficial to tomato grown in the Brazilian semi-arid and should replace other traditionally used practices is little known. Two on-farm experiments were carried out aiming at assessing the yield response of 'Trucker' hybrid tomato to plastic mulching in interaction with other practices, viz, irrigation, earthing up, and plant population. The first experiment consisted of a randomized block design with six treatments arranged in a 3 x 2 factorial and replicated four times: three crop practices (earthing up, plastic mulching and bare soil) combined with two plant populations (12,500 and 10,416 plants ha-1). The second experiment was a randomized complete block design with four replications, in a splitplot arrangement. Irrigation levels (305, 440, 495, 610 and 725 mm cycle-1) were assigned to plots, and mulching and earthing up to subplots. Fruit diameter, fruit weight and crop yield were evaluated. Plastic mulching had no effect on crop yields and water-use efficiency at both experiments. Overall, the results suggest planting 'Trucker' tomato at 12,500 plants ha-1, 580-630 mm cycle-1 of irrigation, and without plastic mulching. [ABSTRACT FROM AUTHOR]

Banana production stands out in Brazilian semiarid agriculture; however, due to little availability of water resources, associating water-saving technologies with the knowledge of parameters involved in the interplay between plants and soil is critical to improving banana production systems. The objectives of this study were to evaluate the effect of planting densities and irrigation levels on root length density of 'BRS Platina' banana and to correlate root parameters to crop yield and leaf area. A randomized block design was used, with factors arranged in split-split plots and treatments replicated three times: four irrigation levels (55%, 70%, 85% and 100% ETc) were assigned to plots, four planting densities (1,600; 2,000; 2,666; and 3,333 plants ha-1) to subplots and distance from pseudostem or sampling depth to sub-subplots. Root length density (RLD) was measured at five distances from the pseudostem, longitudinally to a row of plants: 0.10, 0.25, 0.50, 0.75 and 1.10 m; and at three depths for each distance: 0 to 0.20 m, 0.20 to 0.40 m and 0.40 to 0.60 m from surface level. Root length densities were highest at 100% ETc irrigation level and at 2,666 plants ha-1 and 3,333 plants ha-1, within 0.31 m deep and within 0.78 m of the pseudostem. Irrigation interacts with root system, and coupled with higher planting densities, contributes to increasing crop yields of 'BRS Platina' banana plants. [ABSTRACT FROM AUTHOR]

Chamomile is an important socioeconomic option for family farming. Its cultivation involves manual management practices and herbicide use restriction, and knowledge regarding weed interference on the yield of chamomile capitula and essential oil quality is still limited. In this perspective, this study aimed to assess the effect of sowing dates, plant spacings, and hoeing management on the yield of chamomile capitula, essential oil yield, and essential oil content under the environmental conditions of a region with a Humid Subtropical climate without defined seasons. The experiments were conducted on four dates (March 18, March 28, June 31, and August 30, 2017, with plants spaced 0.05, 0.10, 0.15, 0.20, 0.30, and 0.40 m within rows. On March 28 and May 14, 2018, the spacings between plants in the row were 0.05, 0.10, 0.15, and 0.20 m, including two hoeing managements (with and without weeds). The variables analyzed in the two years were the yield of dry capitula, the dry mass of chamomile plants and weeds (g m-²), and the content and yield of essential oil in 2018. The sowing dates influenced the yield of floral capitula, the essential oil content, and the essential oil yield as a function of the duration of the cycle and weed occurrence. The autumn sowings resulted in a higher yield of floral capitula in both years. A linear reduction trend was also verified in the yield of floral capitula with the increase in plant spacing within the row from 0.05 to 0.20 m in the two crop years. [ABSTRACT FROM AUTHOR]

Initial seed vigor and sowing density interact in establishment of plants in the field, and can thus affect expression of the plasticity of the wheat crop and the yield and physiological quality of the seeds produced. The aim of this study was to evaluate the effect of seed vigor levels in combination with sowing densities on the yield and physiological potential of wheat seeds. The cultivars BRS Gralha-Azul and BRS Sabiá were used in a randomized block experimental design in a 2 × 4 factorial arrangement, with four replications. The treatments consisted of seeds of high and low vigor and four sowing densities (150, 250, 350, and 450 seeds.m-2). The following evaluations were made: seed yield, germination, first germination count, seedling length, seedling dry matter, accelerated aging, emergence speed index, and seedling emergence in sand. An increase in sowing density favors the seed yield of both cultivars; however, it reduces the vigor of the seeds produced by the cultivar BRS Gralha-Azul, especially of the seeds produced by plants originating from high vigor seeds. For the cultivar BRS Sabiá, an increase in sowing density decreases the germination performance of seeds produced by plants originating from low vigor seeds. [ABSTRACT FROM AUTHOR]

Chicken weed is a significant weed in India and it occurs under onion cultivated field at Birnin Kebbi in the Sudan Savannah, Nigeria. On-farm experiment was conducted at Birnin Kebbi during the 2017/2018 and 2018/2019 dry season to evaluate the effect of plant population and weed control methods on the management of chicken weed (Portulaca quadrifida) alongside other weeds in onion field. The experiment consisted of three plant populations (500,000, 333,333 and 250,000 plants per hectare) and twelve weed control methods (Pendimethalin at 1.0 kg a.i. ha-1, + 1Hw; pendimethalin at 1.5 kg a.i. ha-1 + fluazifop-p-butyl at 2.0 kg a.i. ha-1; pendimethalin at 2.0 kg a.i. ha-1; butachlor at 2.0 kg a.i. ha-1 + 1Hw; butachlor at 2.8 kg a.i. ha-1 + oxyfluorfen at 1.0 kg a.i. ha-1; butachlor at 3.6 kg a.i. ha-1; fluazifop-p-butyl at 2.0 kg a.i. ha-1; oxyfluorfen at 1.0 kg a.i. ha-1 + 1Hw; hoe weeding at 3 (WAT); hoe weeding at 3 and 6 WAT; weed free and weedy check). The experiment was laid out in a randomized complete Block design replicated three times. Results showed that weed, growth and yield parameters were not significantly affected by plant population. Pendimethalin at 1.5 kg a.i. ha-1 + fluazifop-p-butyl at 2.0 kg a.i. ha-1 and weed free plots consistently recorded the lowest weed cover and highest weed control efficiency. Butachlor at 2.0 kg a.i. ha-1 + 1 Hw recorded the lowest crop injury score. Increase in plant height was observed when pendimethalin at 1.0 and 1.5 kg a.i. ha-1 + 1 Hw and fluazifop-p-butyl at 2.0 kg a.i. ha-1 respectively was applied, while application of pendimethalin at 2.0 kg a.i. ha-1 and butachlor at 2.0 kg a.i. ha-1 + 1 Hw recorded highest number of leaves and leaf area. Cured bulb and marketable bulb yield were greater with the use of pendimethalin and butachlor at 1.0 and 1.5 kg a.i. ha-1 + 1 Hw and the pooled data respectively. Application of pendimethalin and butachlor at the rate of 1.0 and 2.0 kg a.i. ha-1 followed by 1 Hw at 6 WAT respectively was therefore recommended for the control of chicken weed alongside other weed species in the ecology. [ABSTRACT FROM AUTHOR]

Reducing the leaf senescence rate could improve the grain yield in maize. In the present study, maize seeds were treated with uniconazole at concentrations of 0 and 25 mg kg-1, and nitrogen was applied at 0, 150, and 225 kg ha-1 to maize crop planted at a density of 105,000 plants ha-1. Applying uniconazole and nitrogen reduced the leaf senescence rate by increasing the leaf area per plant, chlorophyll content, net photosynthetic rate, stomatal conductance, and transpiration rate. Uniconazole and nitrogen increased the electron transport rate, photochemical quenching coefficient, variable fluorescence, maximal quantum yield of PSII photochemistry, and effective quantum yield of PSII photochemistry. Uniconazole and nitrogen reduced the intercellular carbon dioxide concentration, nonphotochemical quenching coefficient, and malondialdehyde content but increased the soluble protein content and antioxidant enzyme activities. Applying uniconazole at a concentration of 25 mg kg-1 and nitrogen at a rate of 150 kg ha-1 obtained the maximum grain yield in maize. [ABSTRACT FROM AUTHOR]

Plant arrangements are a practice that has remained constant for decades, with little research about soybeans, with contrasting rainfall conditions. The purpose of this work was to evaluate the agronomic performance of indeterminate soybean with variation for the plant arrangements, populations and in cultivation of crops. The research was conducted in Arapongas-PR with an experimental design of randomized blocks, organized in a 6x3x2 factorial scheme, with four replications. The variation factors were six populations (100, 200, 300, 400, 500 and 600 thousand plants ha-1), three plant arrangements (0.25 cm, 0.50 cm and 0.25x0.50 cm in paired-rows) and two cultivation of crops. The statistical analysis sought to evaluate the interactions and break down the simple effects and the main effects. Row spacing influenced the variables grain yield, height of the first pod insertion, plant height and leaf area index. Populations with up to 300 thousand plants reached the highest levels of grain yield. The plant arrangement for the paired-rows is superior to traditional spacing, with 4,732 kg ha-1 for the spacing 0.25x0.50 m, 3,817 kg ha-1 for the spacing 0.50 m and 3,628 kg ha-1 for the spacing 0.25 m. [ABSTRACT FROM AUTHOR]

This study assessed the optimal nitrogen (N) fertilizer rate and planting density for the well-adapted upland rice cultivar NERICA_4 on the Fogera Plain. The primary objective was to evaluate the effects of varied planting densities and N-fertilizer rates on upland rice yield and other agronomic parameters. A two-year field study (2020 and 2021) was conducted at the Fogera Rice Research Field Station, testing nine plant densities (75, 87, and 98; 72, 82, and 91; 70, 79, and 89 plants per m 2 and two N rates (115 and 138 kg N ha -1 ). The Crop Simulation Model Crop Environment Resource Synthesis (CSM-CERES-Rice) within the Decision Support System for Agrotechnology Transfer (DSSAT) framework was calibrated and validated using site-specific weather, soil, crop, and agronomic management data from the experiment. Results on the subsequent RMSE, RMSEn, and d index values during the calibration phase were 0.074 t ha -1 , 1.82 %, and 0.86 of grain yield; 0.307 t ha -1 , 3.36 %, and 0.87 of by-product yield; 0.489 t ha -1 , 3.74 %, and 0.79 of top dry biomass yield; and 0.28, 8.24 %, and 0.63 of leaf area index values, respectively. Whereas results on the corresponding RMSE, RMSEn, and d index values during the evaluation phase were: 0.58 t ha -1 , 1.33 %, and 0.90 of grain yield; 0.69 t ha -1 , 0.58 %, and 0.99 of by-product yield; 0.678 t ha -1 , 4.36 %, and 0.67 of top dry biomass yield; and 0.75, 13.92 %, and 0.74 of leaf area index, respectively. The findings of the long-term simulation showed that a 23 % increase in grain yield was achieved with 138 kg N ha -1 and 87 plants per m 2 of planting density, as compared to 115 kg N ha -1 and 75 plants per m 2 of plant density. The recommended optimum plant density and N fertilizer rate were 138 kg N ha -1 with PD2 of plant density for upland rice production in the Fogera Plain., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 Published by Elsevier Ltd.)

Premise: Soil microbes can influence patterns of diversity in plant communities via plant-soil feedbacks. Intraspecific plant-soil feedbacks occur when plant genotype leads to variations in soil microbial composition, resulting in differences in the performance of seedlings growing near their maternal plants versus seedlings growing near nonmaternal conspecific plants. How consistently such intraspecific plant-soil feedbacks occur in natural plant communities is unclear, especially in variable field conditions., Methods: In an in situ experiment with four native tree species on Barro Colorado Island (BCI), Panama, seedlings of each species were transplanted beneath their maternal tree or another conspecific tree in the BCI forest. Mortality and growth were assessed at the end of the wet season (~4 months post-transplant) and at the end of the experiment (~7 months post-transplant)., Results: Differences in seedling performance among field treatments were inconsistent among species and eroded over time. Effects of field environment were detected at the end of the wet season in two of the four species: Virola surinamensis seedlings had higher survival beneath their maternal tree than other conspecific trees, while seedling survival of Ormosia macrocalyx was higher under other conspecific trees. However, these differences were gone by the end of the experiment., Conclusions: Our results suggest that intraspecific plant-soil feedbacks may not be consistent in the field for tropical tree species and may have a limited role in determining seedling performance in tropical tree communities. Future studies are needed to elucidate the environmental and genetic factors that determine the incidence and direction of intraspecific plant-soil feedbacks in plant communities., (© 2024 The Authors. American Journal of Botany published by Wiley Periodicals LLC on behalf of Botanical Society of America.)

Choosing appropriate estimator that provides an accurate and precise prediction of plant population’s density is vital specifically when different density intensities and distribution patterns are concerned. Therefore, the efficiency of plotless plant density estimators for the various spatial patterns found in nature have been examined using a simulated population based on an observed population of Astragalus microcephalus in a semi-arid environment.We first surveyed the density of A. microcephalus in the field to have an estimation of the real density of the species (control method). Then a simulation scheme in three density intensities (low (mean−SD), moderate (equal to mean) and high (mean + SD)) and three distribution patterns (random, regular and aggregated) was drawn. Seven distance-based plant estimators were applied to evaluate their efficiency in the three density intensities and also distribution patterns within eight 40 × 100 m sampling units of the simulated scheme (repeats). The predictive precision and accuracy of the estimators in various density intensities and distribution patters were evaluated using the ideal point error-index and comparing the estimators predicted values with the controls (real densities). Angle Order (AO) and Third Closest Individual (TCI) in regular, TCI and Point Centered Quarter (PCQ) in random and AO in aggregate distribution pattern was the best plotless density estimators of plant populations. Overall, TCI, AO and PCQ were the most accurate and precise estimators of density among the seventh studied estimators in different density intensities and distribution patterns. Using these two estimators is recommended to achieve an unbiased estimation of plant population’s density.

Abstract: The aim of this study was to evaluate the physiological potential of seeds of white oat cultivars grown at different sowing dates and densities. Two independent experiments were conducted with two different sowing dates in a randomized block experimental design in a 4 × 2 factorial arrangement, with four replications. The treatments consisted of four sowing densities (180, 240, 300, and 360 viable seed.m-2) and two cultivars (IPR Afrodite and IPR Artemis). The following evaluations were made: thousand seed weight, germination percentage, first germination count, seedling length, seedling dry matter, emergence speed index, and seedling emergence in sand. Joint analysis of variance was carried out on the data regarding sowing dates separately for the cultivars. The mean values for sowing dates were compared by the F test; and polynomial regression analysis up to the second degree at 5% probability was conducted on the densities. The seeds produced by the plants grown from the first sowing date had better vigor than those produced by plants from the later sowing date. The increase in sowing density reduces the weight and vigor of the seeds produced by plants from the second sowing date. For the IPR Afrodite and IPR Artemis cultivars, the use of 180 seed.m-2 in the first growing period allows production of seeds with greater physiological potential.

The anthropophytisation processes pose a real threat to the phytodiversity on the territory of Ukraine. To study the interpopulation variability and to analyze the factors leading to the excessive increase in quantity of the adventive species individuals in the conditions of anthropogenic transformation, we took as a model the invasion species on the territory of Ukraine: Solidago canadensis L. and Solidago gigantean Ait. According to the study of the morphological signs variability in local populations S. canadensis and S. gigantea in different ecological conditions, we have revealed that the morphometric signs (length of the ramet, number of leaves, length of inflorescences, number of flowers in the inflorescences) of the S. canadensis ramets are characterized by medium and high intrapopulations variability (V = 11.46-68.67 %), and S. gigantea ramets are characterized by insignificant and high levels of intrapopulation variability (V = 7.01-90.04 %), which correlates with unfavourable conditions of anthropogenically transformed habitats. According to the study results, we have discovered that the depressive vitality type, and, correspondingly, the low vitality level is common for the local populations of S. canadensis for ruderal biotopes of anthropogenic herb stands, ruderal biotopes of fallows on sand, highly artificial broadleaved deciduous forestry plantations and fruit and nut tree orchards. Such a vitality type of S. canadensis populations is probably explained by the high level of digression of the above-mentioned biotopes. The local population of the ruderalized thickets of bushes is characterized by the comparatively high value of the vitality index, which is due to the favorable edaphic conditions. On the other hand, the local populations of S. gigantea of ruderal biotopes of anthropogenic herb stands, ruderal biotopes of fallows on sand, highly artificial broadleaved deciduous forestry plantations, fruit and nut tree orchards and ruderalized thickets of bushes are characterized by a prosperous vitality type and, accordingly, a high level of vitality.

In this paper, a non-linear mathematical model is proposed and analyzed to study the dynamics of plant-pollinator-pesticide interactions. Analysis of the existence of equilibrium points is done. Sufficient conditions for local as well as global stability have been derived. A threshold value of the energetic reward is obtained above which the dynamical system persists uniformly. Further, numerical simulations are performed to confirm the analytic results and to deduce some other important conclusions. It is shown that the plant and pollinator populations support the growth of each other and are mutually dependent when the energetic reward is sufficiently high. Observations show that equilibrium values of plant and pollinator populations can be maintained for high energetic rewards even though pesticides are present. However, if energetic rewards are low, the presence of pesticides will lead to plant extinction. [ABSTRACT FROM AUTHOR]

The adoption of different plant arrangements in the soybean crop can promote morphological changes in the plants, which may influence the grain yield. In this context, the spatial arrangement allied to a determined growth and higher cycle variety may be an alternative for the management of the soybean crop under adverse edaphic-climatic conditions. In this way, the objective of this work was to evaluate the agronomic performance and the productive components of the BRS Valiosa RR® soybean cultivar, with determined growth in different plant populations and between rows. The trial was installed in Rio Verde/GO at 2012/13 agricultural year. A randomized complete block design was used in a factorial arrangement 4x4 with four replications. It was evaluated four spacing between rows (20; 40; 20/40 and 20/60 cm) associated with four plant populations (200,000, 300,000, 400,000 and 500,000 ha-1 plants). The BRS Valiosa RR® cultivar showed potential to reduce the plant population without causing reductions in grain yield, regardless of the spacing between rows. [ABSTRACT FROM AUTHOR]

Copyright of Listy Cukrovarnicke a Reparske is the property of VUC Praha a.s. 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.)

Banana is one of the most abundantly consumed fruits in the world for its contribution to human nutrition, including an important content of potassium. Given the social contribution of this crop in the cropping areas of Colombia, it is necessary to develop agronomic management strategies that contribute to increasing productivity and offering alternatives that regulate the effects of climate seasonality on banana production in the Urabá region of Colombia. For this purpose, different planting densities (2,000, 2,500, 3,000 and 3,500 plants ha-1) and planting arrangements (triangle, rectangle and double furrow), plus a relative control (1,700 plants ha-1 under triangle arrangement), were evaluated in the banana cv. Williams. The experimental design corresponded to randomized complete blocks in a 4 x 3 + 1 (densities x arrangements + control treatment at 1,700 plants ha-1) factorial arrangement. During harvest, the following parameters were monitored: bunch weight, number of hands and fingers per bunch, finger length and diameter, bunch ratio and percentage of loss per bunch. Two analyses of variance were carried out, a general one including the control treatment, and an additional one excluding it. The double furrow planting arrangement favored the productivity of the crop in terms of a greater assimilation and lesser loss records at the bunch level. The strong correlation of the studied variables with the double furrow arrangement became evident. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the physiological potential of seeds of white oat cultivars grown at different sowing dates and densities. Two independent experiments were conducted with two different sowing dates in a randomized block experimental design in a 4 x 2 factorial arrangement, with four replications. The treatments consisted of four sowing densities (180, 240, 300, and 360 viable seed.m-2) and two cultivars (IPR Afrodite and IPR Artemis). The following evaluations were made: thousand seed weight, germination percentage, first germination count, seedling length, seedling dry matter, emergence speed index, and seedling emergence in sand. Joint analysis of variance was carried out on the data regarding sowing dates separately for the cultivars. The mean values for sowing dates were compared by the F test; and polynomial regression analysis up to the second degree at 5% probability was conducted on the densities. The seeds produced by the plants grown from the first sowing date had better vigor than those produced by plants from the later sowing date. The increase in sowing density reduces the weight and vigor of the seeds produced by plants from the second sowing date. For the IPR Afrodite and IPR Artemis cultivars, the use of 180 seed.m-2 in the first growing period allows production of seeds with greater physiological potential. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Agricultura Irrigada - RBAI is the property of Revista Brasileira de Agricultura Irrigada - RBAI 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 cultivars adapted to regions of cultivation with regular coffee tree numbers per area and the adequate nutritional state are premises to obtaining high coffee yield. The coffee triennial production and the leaf macronutrient contents of coffee tree cultivars were studied under different plant densities on a randomized completely blocks design, with 3 replications, in split plot system, the parcels corresponding to the populations and the sub parcels to the cultivars. Catuaí Amarelo (IAC 47), Obatã (IAC 1669-20), Acaiá (IAC 474-19) and Icatu Amarelo (IAC 2944) were planted in the population of 2500, 5000, 7519, 10000 plants per ha-1 with one plant per hole and the 2500 plant ha-1 with two plants per hole. The recommended fertilization was equally distributed among the plants of each treatment, but the liming wasn’t done after the coffee tree plantation. Increments in the coffee tree populations increased the triennial coffee yield per area, decreased the yield per plant and increased the leaf contents of phosphorus, potassium and sulfur in the plants. Equal or higher macronutrient contents were found in the coffee trees under dense system than on the ones under conventional and highest level of the elements in the taller cultivars and the lower contents in the Obatã. An increasing coffee yield and lower phosphorus, calcium and sulfur concentrations were observed with one plant per hole than in the ones with two. The coffee tree cultivars and populations showed excessive levels of nitrogen and sulfur, but adequate levels of other macronutrients.

The maintenance of adaptability to the exposure to agroecological extreme environments is generally a feature after the long-term domestication of crops. Auxin influences plant growth in all environments. At present, the research on the auxin response factors (ARFs) has been very in-depth. However, there is still a large gap in the research on the origin, evolution, and regulatory networks of the Auxin-responsive protein (AUX/IAA) family. Here, we identified 495 AUX/IAAs from 19 representative species covering aquatic algae to angiosperms and found that they originated from early bryophytes and mainly expanded by polyploidy in angiosperms. In the domesticated crop quinoa, the evolutionary model of the IAA family is relatively independent and forms a robust regulatory network with auxin signals and energy metabolism pathways. In the nitrogen-deficient environment, CqIAAs (Chenopodium quinoa AUX/IAAs), auxin signals, and TCA pathway genes induced expression in young roots to promote root elongation and could regulate the balance of carbon and nitrogen metabolism to maintain the adaptation of early seedlings in poor environments. Furthermore, a rapidly evolving CqIAA (AUR62011942) not only has different expression levels in two quinoa seeds but also has a significant stress response when seedlings face nitrogen deficiency stress, which may be a key factor in the adaptive regulation of the barren environment. Our research provides valuable clues for understanding the origin, evolution, and functional innovation of auxin signaling and also provides a reference for future agricultural breeding in the context of global environmental changes.

Silene viscaria (L.) Jess. is a common species of Central Russian flora. It has attractive purple, crimson, or darkpink inflorescences. Some literature sources indicate the possibility of white-colour flowers. However, there are no reliable published evidences of these cases. In this report, a record of S. viscaria plants with achromatic, white, flowers at the southern border of the Mordovia State Nature Reserve is presented. Some morphological traits of flowering individuals were measured: the height of reproductive individuals, the number of whorls of lateral branches per an inflorescence, the number of flowers per an inflorescence, the length of an inflorescence, and the percentage of an inflorescence length from a flowering plants height. Data on the flora accompanying S. viscaria are presented. As a result, no significant differences between plants with achromatic flowers and plants with coloured flowers have been found. However, the height of white-flower individuals was slightly higher. We suggest accumulating data on a phenomenon of the flower’s achromatism amongst different groups of plants in order to try to understand the frequency of this phenomenon and perhaps its impact on plants biology.

At maximum vegetative growth, sprays with fungicide to control Asian rust (Phakopsora pachyrhizi Sydow and P. Sydow) should reach high canopy penetration and plant coverage. Therefore, the central objective of this study was to determine leaf area, spray deposition, and plant coverage by fungicides sprayed on soybeans as a function of sowing seasons and plant population densities with reduced doses of tebuconazole and azoxystrobin + cyproconazole. Field experiments were conducted in the 2009/2010 and 2010/2011 crop years, using a medium-cycle soybean cultivar MG/BR–46 (Conquista) under a natural infestation of Asian soybean rust. Leaf area (LA) and leaf area index (LAI) were measured at three developmental stages (V8, R2, and R4). Spray deposition and coverage were evaluated during the first fungicide spraying. As results, LAI decreased as plant population decreased. Despite the lower LAIs, smaller plant populations had no effect on spray deposition and plant coverage. Both fungicides presented similar depositions on all thirds when plants had lower development.

Banana is a crop of major importance for the Brazilian semiarid region. However, because of the low availability and irregularities of the rainfall in this area, it is necessary to combine techniques that allow a higher water-use efficiency. This study aimed to evaluate the influence of different combinations of irrigation depths and planting densities on the precocity, yield and water-use efficiency of BRS Platina banana plants, in the semiarid region of the Bahia state, Brazil. A randomized block design with four replicates was used, in a split-plot arrangement. Irrigation depths of 55 %, 70 %, 85 % and 100 % of the crop evapotranspiration (ETc) were assigned to the plot, and the planting densities of 1,600 plants ha-1, 2,000 plants ha-1, 2,666 plants ha-1 and 3,333 plants ha-1 to the split-plot. The hands weight and number of fruits decreased in a linear way with the increase in the planting density (1,600 plants ha-1 to 3,333 plants ha-1) from 10.89 kg to 9.49 kg and from 97.16 to 89.86, respectively; whereas the hands yield (15.5 t ha-1 to 25.79 t ha-1) and the harvest period (442 to 455 days) increased. The number of fruits increased linearly from 89.46 to 98.08 with the irrigation depth of 55 % to 100 % of the ETc. The yield and water-use efficiency increased linearly as the planting density increased (1,600 plants ha-1 to 3,333 plants ha-1) from 5.14 to 8.60, while the water-use efficiency decreased with the irrigation depth from 7.97 to 5.50, conidering 55 % to 100 % of the ETc. It is possible to obtain higher yields and a higher water-use efficiency by using a higher planting density and irrigation levels below 100 % of the ETc.

Herbivores are a diverse group of fauna that shape the distribution and composition of plant communities. In some cases, herbivory may prevent the re-establishment of submerged aquatic vegetation (SAV), such as Vallisneria americana, into systems. The goal of this study was to investigate the role and nature of herbivory on V. americana transplants with camera and transect surveys of grazing intensity and with field and laboratory grazing experiments using a suspected herbivore, the blue crab, Callinectes sapidus. Camera surveys recorded C. sapidus clipping and consuming shoots of V. americana for the first time. Grazing intensity surveys in low-salinity regions of the lower Chesapeake Bay indicated that the majority of V. americana transplants (50–75%) were clipped off at their base within one week of planting. Field and laboratory experiments demonstrated that C. sapidus clips and consumes V. americana as well as other rapidly colonizing, non-native SAV. Analysis of the gut contents of C. sapidus caught in SAV beds in the Chesapeake Bay revealed that SAV comprised 16% of their stomach contents, suggesting low levels of C. sapidus herbivory occurred over a wide area. Callinectes sapidus is yet another animal documented to consume SAV for some portion of their diet. These results also suggest that herbivores or omnivores, including C. sapidus, can serve as bottlenecks to recovery of SAV, like V. americana, in some areas. Herbivores may not serve as bottlenecks in other environments or to other SAV with more rapid plant growth or higher recruitment levels that may overcome grazing pressure. [ABSTRACT FROM AUTHOR]