Response Of Common Bean Research Articles

Hydrotime model can describe the response of common bean (Phaseolus vulgaris L.) seeds to temperature and reduced water potential

Germination parameters of the response to temperature and water potential from four common bean (Phaseolus vulgaris) lines based on thermal-time and hydrotime concepts were estimated to verify to what extent they can predict germination under different thermal and water conditions. The cultivars IPR Uirapuru and IAPAR 81 (drought-tolerant), and Grauna and Carioca (not tolerant) were used. The isothermal assays were performed in a temperature gradient block, and the assays with different osmotic potentials (PEG 6000) were performed in germination chambers. Seeds from drought-tolerant cultivars spent less time to germinate at supra-optimum temperatures than non-tolerant ones, and the cultivar Uirapuru (drought-tolerant) germinated faster in response to reduced Ψ and low temperatures. The parameter Ψb(50) did not discriminate between drought-tolerant and non-tolerant lines at the infra- optimum temperature range, but it can be used to identify drought-tolerant lines at high temperatures. In general, the hydrotime model reproduced the actual germination data relatively well, chiefly at higher temperatures. This study evidenced that the hydrotime model can be used to describe the germination of common bean seeds under reduced water potentials, and as a screening tool for drought-tolerant bean genotypes.

Differential proteomic analysis of drought stress response in leaves of common bean (Phaseolus vulgaris L.)

The majority of common bean plants are cultivated under drought conditions. Maintaining crop yields under drought stress is thus one of the biggest challenges facing bean production. In order to improve our understanding of the complex mechanisms involved in the response of common bean (Phaseolus vulgaris) to drought stress, a proteomic approach was used to identify drought-responsive proteins in leaves of two cultivars differing in their response to drought, Tiber and more sensitive Starozagorski čern. 2D-DIGE was used to compare differences in protein abundance between control and stressed plants. Fifty-eight proteins whose abundance changed significantly were identified by LC-MS/MS in Tiber and 64 in Starozagorski čern. The majority of identified proteins were classified into functional categories that include energy metabolism, photosynthesis, ATP interconversion, protein synthesis and proteolysis, stress and defence related proteins. Details of the function of the identified proteins and their abundance profiles in Tiber and Starozagorski are discussed. Interactions between identified proteins were demonstrated by bioinformatics analysis, enabling a more complete insight into biological pathways and molecular functions affected by drought stress. The results form the basis for a further understanding of the biochemical mechanisms of drought response in common bean.

Effect of irrigation on the relationships between leaf gas exchange related traits and yield in dwarf dry bean grown under Mediterranean conditions

Drought is a major yield constraint of crop productivity. Determining physiological traits involved in the response of common bean to drought stress could lead to improving drought tolerance. A two-year study (2008 and 2009) was carried out to determine the physiological traits that are associated with drought tolerance for maximum dry bean seed yield (SY), and water use efficiency (WUE) in northern Greece. Two cultivars (Borlotto and Green crop) were evaluated at five water levels based on crop evapotraspiration (ETm) (100% –I100, 75% –I75, 50% –I50, 25% –I25 and 0% –I0). Under higher irrigation regimes (I75, I100), higher seed yield (SY) was found due obviously to a denser canopy (higher LAI), with greener (higher SPAD), and more photosynthetically active leaves (higher net assimilation rate-A, transpiration rate-E and stomatal conductance-gs) compared with lower irrigation rates. In addition, under higher irrigation regimes (I75, I100), a higher partitioning of dry matter to seeds (higher HI) was evident. Instantaneous water use efficiency (A/E) increased with increasing irrigation levels. On contrary to negative correlations in C3 species, carbon isotope discrimination (Δ) was positively correlated to A/E doubting its reliability as a long-term assessment of water use efficiency in bean. However, Δ was strongly correlated with SY indicating that higher water availability contributed to higher yields. The early flowering cultivar (Borlotto) had higher SY compared with the late flowering one (Green crop), however, no significant difference was found at the physiological traits between the two cultivars. Leaf-to-air temperature difference (ΔT) showed to be a good threshold indicator of non-stress water conditions in bean during the post-filling period since a value higher than 2.95°C indicated a severe water stress.

Combined inoculation with Glomus intraradices and Rhizobium tropici CIAT899 increases phosphorus use efficiency for symbiotic nitrogen fixation in common bean (Phaseolus vulgaris L.)

This study compared the response of common bean (Phaseolus vulgaris L.) to arbuscular mycorrhizal fungi (AMF) and rhizobia strain inoculation. Two common bean genotypes i.e. CocoT and Flamingo varying in their effectiveness for nitrogen fixation were inoculated with Glomus intraradices and Rhizobium tropici CIAT899, and grown for 50days in soil–sand substrate in glasshouse conditions. Inoculation of common bean plants with the AM fungi resulted in a significant increase in nodulation compared to plants without inoculation. The combined inoculation of AM fungi and rhizobia significantly increased various plant growth parameters compared to simple inoculated plants. In addition, the combined inoculation of AM fungi and rhizobia resulted in significantly higher nitrogen and phosphorus accumulation in the shoots of common bean plants and improved phosphorus use efficiency compared with their controls, which were not dually inoculated. It is concluded that inoculation with rhizobia and arbuscular mycorrhizal fungi could improve the efficiency in phosphorus use for symbiotic nitrogen fixation especially under phosphorus deficiency.

No tillage affects the phosphorus status, isotopic composition and crop yield of Phaseolus vulgaris in a rain-fed farming system

Conservation tillage promotes the accretion of soil organic matter and often leads to improved soil fertility and moisture availability. However, few studies have looked at the physiological response of crop plants to different tillage practices. It was therefore hypothesised that measuring the nutrient concentrations and stable isotope composition (δ(13)C, δ(18)O, δ(15)N) of shoots could help evaluate the physiological response of common bean (Phaseolus vulgaris L.) to different tillage treatments (no tillage (NT) and mouldboard ploughing (MP)) in a rain-fed farming system in northern Mexico. NT significantly enhanced shoot phosphorus concentration in bean plants. Tillage exerted a negative effect on the extent of root colonisation (%) by arbuscular mycorrhizal fungi (AMF). Lower shoot δ(18)O but unchanged δ(13)C values in plants from the NT system suggest enhanced stomatal conductance but also enhanced photosynthetic rate, which overall resulted in unchanged water use efficiency. Bean plants in the NT system showed lower shoot δ(15)N values, which suggests that a larger proportion of total plant nitrogen was obtained through atmospheric nitrogen fixation in this treatment. Greater diversity of AMF soil communities and heavier colonisation of roots by AMF in the NT compared with the MP system appeared to contribute to improved crop nutrition, water relations and yield in this rain-fed agroecosystem.

Yield, Nutrient Uptake, and Changes in Soil Chemical Properties as Influenced by Liming and Iron Application in Common Bean in a No-Tillage System

Soil acidity is the principal limiting factor in crop production in Oxisols, and deficiency of micronutrients has increased in recent years because of intensive cropping. A field experiment was conducted over three consecutive years to assess response of common bean (Phaseolus vulgaris L.) to lime and iron (Fe) applications on an Oxisol in a no-tillage system. Changes in selected soil chemical properties in the soil profile (0- to 10- and 10- to 20-cm depths) with liming were also determined. Lime rates used were 0, 12, and 24 Mg ha–1, and Fe application rates were 0, 50, 100, 150 200, and 400 kg ha–1. Both lime and Fe were applied as broadcast and incorporated in the soil. Grain yields of common bean were significantly increased with the application of lime. Iron application, however, did not influence bean yield. There were significant changes in soil profile (0- to 10-cm and 10- to 20-cm depths) in pH, calcium (Ca2+), magnesium (Mg2+), hydrogen + aluminum (H+ + Al3+), base saturation, acidity saturation, cation exchange capacity (CEC), Ca2+ saturation, Mg2+ saturation, potassium (K+) saturation, and ratios of Ca/Mg, Ca/K, and Mg/K. These soil chemical properties had significant positive association with common bean grain yield. Averaged across two depths and three crops, common bean produced maximum grain yield at pHw 6.3, Ca2+ 3.8 cmolc kg–1, Mg2+ 1.1 cmolc kg–1, 3.5 H+ + Al3+ cmolc kg–1, acidity saturation 41.8%, CEC 7.5 cmolc kg–1, base saturation 57.4%, Ca saturation 45.2%, Mg saturation 14.2%, K saturation 9.1%, Ca/Mg ratio 3.1, Ca/K ratio 22.6, and Mg/K ratio 6.7.

Genotypic response of common bean to natural field populations of bean fly ( Ophiomyia phaseoli) under diverse environmental conditions

Bean fly is a significant pest of common bean in semi-arid areas of East Africa. Apart from inadequate moisture in the dry land, bean fly simultaneously contributes negatively thereby adversely affecting bean productivity. The objectives of this study were to (1) identify sources of resistance to bean fly available in landraces, (2) confirm stability of host plant resistance in drought stress and (3) determine the effect of drought stress and seasonal variation on common bean genotypes in relation to bean fly attack for adaptability to the semi-arid areas of East Africa. Sixty four genotypes including landraces, bean fly resistant lines and local checks were evaluated for seed yield, 100-seed weight, days to maturity, plant mortality and pupae in stem in an alpha lattice design with two replications. This was under drought stressed (DS) and non-stressed (NS) environments and two treatments (insecticide sprayed and natural infestation) for three cropping seasons between 2008 and 2009. Genotypes differed in their reaction to natural bean fly attack under drought stressed (DS) and non-stressed (NS) environments over different cropping seasons. However, the effect of bean fly appeared to vary between the long rains (LR) and short rains (SR). It was observed that an increase in number of pupae per stem resulted in a higher plant mortality. The range of seed yield was from 345 to 1704 kg ha −1 under natural infestation and from 591 to 2659 kg ha −1 under insecticide protection. Seed yield loss ranged from 3 to 69%. The resistance of most of the bean fly resistant lines seemed to break down in presence of DS owing to their dismal performance. Screening of genetic resources in common bean to breed for host plant resistance to bean fly offers high potential of success if researchers take full advantage of the diversity available within the landraces.

Resposta da cultura do feijoeiro à adubação nitrogenada e à inoculação com rizóbio

O manejo adequado da adubação nitrogenada representa uma das principais dificuldades da cultura do feijoeiro (Phaseolus vulgaris L.). No entanto, a fixação biológica de nitrogênio é uma fonte alternativa de suprimento deste nutriente à cultura. O presente estudo teve como objetivo avaliar a resposta do feijoeiro à inoculação com rizóbio e ao parcelamento de fertilizante nitrogenado em termos de nodulação das plantas e produtividade de grãos da cultura, bem como a viabilidade econômica da aplicação de fertilizante nitrogenado e, ou, inoculação com rizóbio em feijoeiro. O experimento foi conduzido num Latossolo Vermelho distroférrico, em Dourados, MS. O delineamento experimental utilizado foi o de blocos casualizados, com seis repetições. Os sete tratamentos consistiram da aplicação parcelada de fertilizante nitrogenado em diferentes doses (0, 20, 40, 80 e 160 kg ha-1 de N como ureia) na cultura do feijoeiro, cv. Pérola, além de controles com inoculação de Rhizobium tropici combinada ou não com aplicação de 20 kg ha-1 de N. A análise econômica foi efetuada considerando os custos da ureia e sua aplicação a lanço, além do custo do inoculante; os demais custos não foram considerados, por não haver diferença entre os diferentes tratamentos. Foram obtidos o acréscimo de produtividade, o custo de produção, o acréscimo da receita bruta e o acréscimo da receita líquida dos tratamentos, em relação à testemunha sem inoculação e sem adubação nitrogenada. Embora a nodulação das plantas não tenha sido alterada pelos tratamentos, verificou-se tendência de redução conforme o aumento da dose de N aplicada. A inoculação com rizóbio selecionado promoveu rendimentos de grãos de feijoeiros equivalentes à aplicação de 80 kg ha-1 de N. Quando acrescida da adubação com 20 kg ha-1 de N no plantio, a inoculação com rizóbio propiciou acréscimo de receita líquida semelhante à aplicação de 160 kg ha-1 de N e superior ao tratamento com a adubação de 20 kg ha-1 de N sem inoculação, evidenciando a sua importância para obtenção de maior rentabilidade na cultura do feijoeiro.

Liming and Manganese Influence on Common Bean Yield, Nutrient Uptake, and Changes in Soil Chemical Properties of an Oxisol Under No-Tillage System

ABSTRACT Liming is an essential practice in improving yields of annual crops grown on acid soils and deficiency of micronutrients including manganese (Mn) is increasing in crop plants in recent years. A field experiment was conducted during three consecutive years to determine response of common bean to liming and manganese fertilization. The liming rates used were 0, 12, and 24 Mg ha− 1 and Mn rates were 0, 10, 20, 40, 80, and 160 kg ha− 1. Liming significantly influenced grain yield of common bean. The increase in shoot dry weight and pod number were responsible for 44 and 34% variation in bean yield, respectively. Liming significantly influenced soil chemical properties in the top (0–10 cm) as well as in the sub (10–20 cm) soil layer in favor of higher bean yield. Application of Mn did not influence yield of bean and soil chemical properties were also not influenced significantly by Mn application. Average soil chemical properties across two soil layers (0–10 and 10–20 cm) for maximum bean yield were pH 6.8, calcium (Ca) 4.7 cmolc kg− 1, magnesium (Mg) 2.1 cmolc kg− 1, hydrogen (H)+aluminum (Al) 3.4 cmolc kg− 1, acidity saturation 25.9%, cation exchange capacity (CEC) 8.3 cmolc kg− 1, base saturation 70.9 %, Ca saturation 50.6 %, Mg saturation 20.6 %, potassium (K) saturation 2.2, Ca/Mg ratio 2.8, Ca/K ratio 22.1, and Mg/K ratio 8.2.

INFLUÊNCIA DE SISTEMAS AGRÍCOLAS NA RESPOSTA DO FEIJOEIRO (Phaseolus vulgaris L.) IRRIGADO À ADUBAÇÃO NITROGENADA EM COBERTURA

In recent years emphasis has been placed upon the systemic approach of agricultural practices to increase food production. Common bean ( Phaseolus vulgaris L.) has demonstrated to be a suitable crop species as a component of several production systems as it has been shown on the irrigated areas of the Brazilian Central Region. However, general crop management techniques have to be adjusted as a function of the different crop systems available and nitrogen fertilization is one of those. To confirm this hypothesis, common bean response to nitrogen application was evaluated using cultivar Apore under four different irrigated production systems using different crop rotations and soil management practices: A - bean-corn crop rotation, using moldboard plowing in the spring-summer (November/December) and harrowing in the autumn-winter (May-June) season; B – ricebean crop rotation and moldboard plowing only; C - rice/calopogonium-bean crop rotation and harrowing only; D – cornbean crop rotation using continuous no-tillage. Urea, used as the nitrogen source, was applied in topdressing using 0, 25, 50, 75, 100 and 125 kg.ha -1 of N. Field trials were conducted during the fallwinter season, in 1996 and 1997, in a distrofic Dark Red Latosol, at the experimental farm of Embrapa Rice & Beans. Treatment effects were detected on the number of pods per plant, 100 grain weight and grain yield. Higher yields were obtained for systems C and D in which there was less soil disturbance. In system C, the effect of different nitrogen doses fit in a quadratic model and 109 kg.ha -1 , estimated by the regression equation, provided the highest grain yields. In system D the effect was linear indicating that the bean crop demanded more nitrogen under no-tillage. In systems A and B the effect of different nitrogen doses varied according to the year of cultivation. KEY-WORDS: Crop rotation; soil preparation; yield production; productivity; dry beans.

Symbiotic response of common bean (Phaseolus vulgaris L.) to iron deficiency

In order to assess symbiotic activity (the nodules integrity and the iron use efficiency) in common bean (Phaseolus vulgaris L.) under low iron availability, the growth of plants and nodules, the concentration of leghaemoglobin and malondialdehyde, and activity of nitrogenase, catalase, peroxidase and superoxide dismutase were analysed in two (contrasting) common bean varieties subjected to iron deficiency. Results show that nitrogen fixation and leghaemoglobin accumulation decreased at limiting iron availability while malondialdehyde concentration increased under these conditions. The tolerant variety to iron deficiency, ARA14, was clearly less affected than the sensitive one, Coco blanc. A significant stimulation of peroxidase (POD) activity was observed in ARA14 under iron deficiency. At the same conditions, SOD and CAT activities in ARA14 plants were maintained at high level. It was also found that the iron use efficiency for leghaemoglobin accumulation, SOD, CAT and POD activities were critical for the protection of symbiotic system against oxidative burst and for the maintaining of an optimal functioning of N2 fixing system.

Yield, Nutrient Uptake, and Soil Chemical Properties as Influenced by Liming and Boron Application in Common Bean in a No‐Tillage System

In Oxisols, acidity is the principal limiting factor for crop production. In recent years, because of intensive cropping on these soils, deficiency of micronutrients is increasing. A field experiment was conducted on an Oxisol during three consecutive years to assess the response of common bean (Phaseolus vulgaris L.) under a no‐tillage system to varying rates of lime (0, 12, and 24 Mg ha−1) and boron (0, 2, 4, 8, 12, 16, and 24 kg ha−1) application. Both time and boron (B) were applied as broadcast and incorporated into the soil at the beginning of the study. Changes in selected soil chemical properties in the soil profile (0- to 10‐ and 10- to 20‐cm depths) with liming were also determined. During all three years, gain yields increased significantly with the application of lime. However, B application significantly increased common bean yield in only the first crop. Only lime application significantly affected the soil chemical properties [pH; calcium (Ca2+); magnesium (Mg2+); hydrogen (H+)+ aluminum (Al3+); base saturation; acidity saturation; cation exchange capacity (CEC); percent saturation of Ca2+, Mg2+, and potassium (K+); and ratios of exchangeable Ca/Mg, Ca/K, and Mg/K] at both soil depths (0–10 cm and 10–20 cm). A positive significant association was observed between grain yield and soil chemical properties. Averaged across two depths and three crops, common bean produced maximum grain yield at soil pHw of 6.7, exchangeable (cmolc kg−1) of Ca2+ 4.9, Mg2+ 2.2, H++Al3+ 2.6, acidity saturation of 27.6%, CEC of 4.1 cmolc kg−1, base saturation of 72%, Ca saturation of 53.2%, Mg saturation of 17.6%, K saturation of 2.7%, Ca/Mg ratio of 2.8, Ca/K ratio of 25.7, and Mg/K ratio of 8.6. Soil organic matter did not change significantly with addition of lime.

Physiological response of common bean (Phaseolus vulgaris L.) seedlings to salinity stress

The effect of salinity stress on five cultivars of common bean: Bassbeer, Beladi, Giza 3, HRS 516 and RO21 were evaluated on a sand/peat medium with different salinity levels (0, 50 and 100 mM NaCl) applied 3 weeks after germination for duration of 10 days. Salinity had adverse effects not only on the biomass yield and relative growth rate (RGRt), but also on other morphological parameters such as plant height, number of leaves, root length and shoot/root weight ratio. Photosynthesis, transpiration rate and stomatal conductance were adversely affected in all cultivars. Leaf osmotic potential and leaf turgor varied significantly among cultivars and salt levels. The interaction between cultivars and salt levels for photosynthesis, leaf osmotic potential and leaf turgor was highly significant at day 10 of salt treatment. The Na uptake among the cultivars varied in the order: HRS 516 <RO21 <Giza 3 <Bassbeer <Beladi. This suggests that HRS 516 was most tolerant cultivar because it was the only cultivar with the highest survival rate and no symptoms of salt stress. RO21 was the most susceptible to salinity as it showed severe symptoms of salt stress and very low survival rate. Key words: Salinity stress, Na+ ions, physiology, photosynthesis, water relations, common bean (Phaseolus vulgaris L.).

Physiological response of common bean (Phaseolus vulgaris L.) seedlings to salinity stress

The effect of salinity stress on five cultivars of common bean: Bassbeer, Beladi, Giza 3, HRS 516 and RO21 were evaluated on a sand/peat medium with different salinity levels (0, 50 and 100 mM NaCl) applied 3 weeks after germination for duration of 10 days. Salinity had adverse effects not only on the biomass yield and relative growth rate (RGRt), but also on other morphological parameters such as plant height, number of leaves, root length and shoot/root weight ratio. Photosynthesis, transpiration rate and stomatal conductance were adversely affected in all cultivars. Leaf osmotic potential and leaf turgor varied significantly among cultivars and salt levels. The interaction between cultivars and salt levels for photosynthesis, leaf osmotic potential and leaf turgor was highly significant at day 10 of salt treatment. The Na uptake among the cultivars varied in the order: HRS 516 highest survival rate and no symptoms of salt stress. RO21 was the most susceptible to salinity as it showed severe symptoms of salt stress and very low survival rate.

Response of Common Bean (Phaseolus vulgaris L.) to Different Levels of Shade

Response of Common Bean (Phaseolus vulgaris L.) to Different Levels of Shade

Genotypic Response of Common Bean (Phaseolus vulgaris L.) to Moisture Stress Conditions in Kenya

The aim of this study was to determine drought response of thirty bean genotypes under glasshouse and field conditions (Kenya) during 1994. The experiment was laid in a Randomized Complete Block in split-plots design with three replications. Significant (p<0.05) genotypic differences in drought resistance were observed under moisture stress conditions. Significant interaction (p<0.01) between variety and moisture level were observed both in the glasshouse and in the field. Drought resistant genotypes showed high relative water content in stress environment as compared to susceptible ones. They also took relatively longer time to wilt, consequently showing low soil water content at wilting and lower biomass reductions under moisture stress conditions. A significant negative correlation was obtained between days to permanent wilting and relative water with biomass reduction. Relative water content was positively and significantly correlated to stomatal conductance and days to permanent wilting. Correlation between stomatal conductance and biomass yield reduction was not significant. The responses relative water content and stomatal conductance, in certain conditions, were recognized as beneficial drought resistance indicators and may be used as selection criteria in bean breeding programme

Integrated viewing and analysis of phenotypic, genotypic and environmental data with “GenPhEn arrays”

A recurring challenge in agronomic research is how to interpret large data sets that combine information on genotypes, phenotypes and environments. High-resolution color graphics offer the possibility of presenting such data as pseudo-maps or arrays, where x- and y-coordinates represent genotypes and environments, and the z-values represent phenotypic data using dots or other symbols and an appropriate color scheme to indicate the range of values. This paper describes use of such “GenPhEn arrays” with data from three studies: a survey of leaf thickness in common bean ( Phaseolus vulgaris L.) lines, a multi-location trial of wheat ( Triticum aestivum L.) lines and a simulation analysis for response of common bean to increased air temperature. By standardizing the phenotypic values, the genotypic and environmental effects can be easily viewed and better comprehended, especially when presented in multi-trait arrays. The arrays allow presenting large amounts of data (i.e., 5000 data points or more) in a compact and readily interpretable fashion. Appending symbols to indicate levels of significance of specific effects or to characterize genotypes or environments can further assist interpretation and hypothesis generation. It is expected that GenPhEn arrays can be used by plant breeders, agronomists and others to rapidly examine large sets of data for patterns that merit further study using more quantitative approaches.

Responses of common bean (Phaseolus vulgarisL.) to photosynthetic irradiance levels during three phenological phases

As a dominant component crop in intercropping systems, common bean is exposed to radiation deficit during various phases. An indeterminate cultivar was examined from twenty-seven treatments consisting of all possible combinations of three levels of photosynthetic irradiance, 100, 250 and 400 μmol m -2 s -1 , applied during three phenological phases. Acclimation characteristics to reduced irradiance included lower chlorophyll a/b ratio, reduced stomatal density, increased specific leaf area and leaf area ratio and increased shoot-root ratio. Susceptibility of the phases varied when comparisons were made based on entire phases and a magnitude that considered timing and light interception. Number of pods per plant, the predominant yield component, responded to irradiance level during all phases but most during flowering. For number of seeds per pod the only relevant phase was seed filling while seed weight responded during flowering and seed filling. A significant interaction between the irradiance levels of phases was observed for pod number.

Influência do manejo do solo, lâminas de água e doses de nitrogênio na produtividade do feijoeiro

The research was conducted in 1999, in Selviria, state of Mato Grosso do Sul, objectifying evaluate the bean behavior, in relation of soil management, water depths and sidedressing nitrogen application. A randomized block with four repetitions was used. The treatments used were a combination of soil management, sidedressing nitrogen application and water depths. The evaluations were: dry matter, number of pods and grain/plant, number of grain/pod, weight of 100 grains and grain productivity. The water depths influenced sidedressing nitrogen application positively, causing increments in grain productivity in order of 38% and 74% in L 2 (190mm) and L 3 (230mm), respectively, in relation to L 1 (128mm), for 90kg ha -1 . Soil management with chisel ploughing and moldboard ploughing provided a similar behavior for productive characteristics, differing to harrowing, that had worst influence. Soil management didn’t interfere in common bean response to sidedressing nitrogen application

Calibração de métodos de análise de fósforo e resposta do feijão ao fósforo no sulco

O feijoeiro e o milho apresentam respostas significativas ao P, mas deve-se avaliar adequadamente sua disponibilidade no solo para recomendar adubação fosfatada. O objetivo deste trabalho foi calibrar os métodos Mehlich-1, Mehlich-3 e Resina, pela relação entre teores de P extraídos do solo com produtividade das culturas de feijão e milho, e avaliar a resposta do feijoeiro à adubação fosfatada no sulco. Os tratamentos constituíram-se de 250, 500 e 1.000 kg ha-1 de P2O5 aplicados a lanço, obtendo-se quatro cultivos de feijão 'Carioca' em rotação com milho 'BR 201'. No último cultivo do feijão, as parcelas subdivididas receberam 0, 75, 150 e 300 kg ha-1 de P2O5 no sulco. As produtividades aumentaram com a adubação fosfatada, sendo linear em relação ao feijão até 1.000 kg ha-1 de P2O5, e quadrática em relação ao milho. Os três métodos apresentaram boa capacidade de predição da disponibilidade de P no solo, e mostraram correlação significativa entre si. O nível crítico de P para obter 80% do rendimento máximo para o milho foi de 10, 14 e 17 mg dm-3, respectivamente, pelos métodos Mehlich-1, Mehlich-3 e Resina. O feijão apresentou resposta significativa à adubação fosfatada no sulco, variando com a disponibilidade de P existente no solo.