Search

Soybeans (Glycine max L.) are a crucial crop for global food security, and the state of Rio Grande do Sul (RS), Brazil, plays a significant role. However, climate instability, particularly water stress (WS), is a major concern in this region, causing large interannual yield variability. This study aims to address this issue using an in-silico approach to: i) characterize WS and spatial patterns and their frequency within ENSO events; and ii) explore climate-adaptative management strategies such as planting dates and maturity groups to mitigate the risk of crop failure and maximize seed yield and profits. Crop growth simulations were performed testing three soybean maturity groups (MG, 5.0, 5.8, and 6.4) and eight planting dates (from October 5th to January 20th) over 30 years at 187 locations in RS, Brazil, using APSIM Next Generation. Failure risk was calculated as the percentage of simulations that yielded less than the economic break-even soybean yield in a given scenario. The simulated yields were clustered into four regions: Northeast, North, Central, and Southwest. Four WS seasonal patterns were then defined (no stress, early stress, late stress, and whole season stress). On average, WS reduced yields up to 2 Mg ha-1 (∼50 % relative to the maximum). WS varied among regions, with the SW experiencing more frequent and severe stress (up to 50 % of whole season stress during La Nina). ENSO events influenced WS frequency, with El Niño events associated with reduced stress and La Niña events to increased stress. The MG 5.0 resulted in a higher probability of failure risk in all regions. Early planting dates resulted in the highest yield variability (up to 5 Mg ha-1). Climate-adaptative management strategies, such as optimizing planting dates and maturity groups, resulted in a 15 % reduction in crop failure. Our findings provide valuable insights for developing targeted approaches to enhance soybean yield stability, thereby increasing the resilience of agriculture in the face of future climate uncertainties. [Display omitted] • Soybean maturity groups 5.0, 5.8, and 6.4 coefficients were calibrated. • On average, water stress reduces soybean yields up to 2 Mg ha−1. • The Northeast region of Southern Brazil is minimally influenced by ENSO. • The maturity group 5.0 (short) reported a higher failure risk across all regions. • Early planting dates resulted in the highest yield variability (up to 5 Mg ha−1). [ABSTRACT FROM AUTHOR]

Cover crops play a critical role on conservation and sustainable agriculture due to their well-documented benefits on both soil and crop productivity. Inclusion of legumes (e.g., hairy vetch, Vicia villosa Roth) in the farming system can reduce the nitrogen (N) fertilizer needs for cereals such as maize (Zea mays L.) crop while maintaining or increasing its productivity. The aims of this research study were to quantify the effect of hairy vetch as a cover crop on: i) successor maize yield under varying yield environments (YEs) and fertilizer N rates, and ii) maize N status [N uptake, N nutritional index (NNI), and N fertilizer replacement value (NFRV)] at flowering time. Two field studies were carried out in Southern Brazil under varying YEs. The factors investigated were: YE (low, medium, and high), hairy vetch cover crop (with and without), and fertilizer N rate (0, 60, 120, 180, and 240 kg N ha−1). Under the combination of low YE and low fertilizer N rates (0–60 kg ha−1) with previous vetch, maize displayed the largest yield response and an improvement in its N status. The NNI determined at maize flowering was an efficient index of the vetch effect, increasing delta maize yield response (yield with- minus without-vetch) as the NNI reduced, with more than 10% delta yield response with NNI below 0.85. The NFRV of the hairy vetch represents potential N savings of 151 kg N ha−1 for the LYE, 95 kg N ha−1 for the MYE and from 59 to 45 kg N ha−1 for the HYE depending on the tested fertilizer N rate. The N coming from the legume cover crop in addition to the N fertilization was critical for supplying N to maize and boosting productivity across all YEs. Unlabelled Image • Vetch effects were largest for low N rates and low-to-medium yield environments. • Vetch combining with N fertilizer was critical for satisfying maize N supply and improving yields. • N nutrition index at maize flowering was an efficient index for reflecting the vetch effect. • The N fertilizer replacement value reflects the largest contribution of vetch to maize N nutrition in low yield environment. [ABSTRACT FROM AUTHOR]

The low N use efficiency of vines calls for more efficient fertilization processes, which must mitigate losses caused by volatilization. Thus, N dose applications through different methods, such as fertigation, can potentiate N harnessing by vines. The study aimed to determine ideal N concentration in leaves for the production of high-quality grapes cv ' Alicante Bouschet ' (Vitis vinifera L.) subjected to modes of application and N doses. The experiment was carried out in a bifactorial arrangement (N dose x modes of application) in a vineyard implanted in 2011, in Southern Brazil. The N doses were 0, 20, 40, 60, 80, and 100 kg N ha−1 year−1. The modes of application were N application without irrigation (NAWI), N application followed by irrigation (NAFI), and N application via fertigation (Fert). The study lasted three crop seasons. Complete leaves were collected at flowering and veraison to determine total N concentration. Grape yield and yield components were determined. Total soluble solids, total anthocyanins, and total polyphenols in grape must be assessed. The maximal recovery rate in grapes was at 36 kg N ha−1, when N concentration was higher than 2.75 % in leaves at flowering, and higher than 2.25 % at veraison, regardless of the N application mode. The concentrations of total anthocyanins, total polyphenols, and total soluble solids in grape must have diminished at doses higher than 60 kg N ha−1. Thus, N concentration in leaves can be used as a reference for grape yield, the concentration of anthocyanins, and soluble solids as indicators of high-quality grape. [ABSTRACT FROM AUTHOR]

• Nitrogen supply strategies, such as fertigation, favors N uptake by vines. • Fertigation is efficient to anticipate the young grapevine stand and its productive cycle. • The higher nitrogen uptake reduces the grape quality and anthocyanins concentration. • Nitrogen supply followed by irrigation enables vines to produce twice as many grapes. The aim of this study was to evaluate yield and chemical composition of the must in grapevines subjected to Nitrogen (N) supply methods in sandy soils. The vineyard cultivar was ' Alicante Bouschet ' (Vitis vinifera L.) grafted on 1103 Paulsen rootstock, in southern Brazil. The treatments consisted of the application of 20 + 20 kg N ha−1 without irrigation (NWI), 20 + 20 kg N ha−1 followed by irrigation (NFI), 20 + 20 kg N ha−1 via fertigation (NF), 20 kg N ha−1 via fertigation (½NF), and a control (C) without N application. The study was conducted during four crop seasons. Leaves were collected at flowering and veraison to determination N concentration. Stem diameter, grape yield and its components were determined. In the must were evaluated the total soluble solids (TSS), pH, total titratable acidity (TTA) and total anthocyanins (TA). The concentration of nitrate and ammonium in soil solution was determined. N application followed by irrigation or N supplied via fertigation provided to the vines larger stem diameters and leaf N concentrations, in most crop seasons. Grapevines submitted to N application via fertigation or followed by irrigation presented higher yields than conventional application without irrigation, and between two and three times higher than the control. N supply methods little affected total soluble solids contents. The application of N to the soil, regardless of the N supply method, decreased the anthocyanin concentration in the grape must, due to the dilution effect on the pulp/skin ratio, promoted by the yield increase. [ABSTRACT FROM AUTHOR]

• Relative abundance of ureides (RAU) reveals changes in soybean N sources. • The accurate dry tissue RAU estimation relies on the soybean plant fraction. • Basal stem RAU reflects values from the entire main stem. • Upper leaflets and upper petiole RAU poorly correlate with main stem RAU. The present study aims to compare the relative abundance of ureides (RAU) among soybean Glycine max (L.) Merr.] plant fractions in contrasting trial settings and under three nitrogen (N) rates, designed to create variability on symbiotic N fixation. A greenhouse and a field experiment evaluated the RAU in plant fractions (base of the main stem, petiole and leaflets of the uppermost fully developed leaf) at varying growth stages and under absent, intermediate, or high N fertilization rates. The RAU was determined by measuring dry tissue nitrate and ureides and considered the entire main stem as benchmarking plant fraction, previously calibrated based on 15N isotope methods. The main outcomes of this study were: 1) RAU in the base of the stem accurately reflected the one obtained in the main stem; 2) upper leaflets RAU poorly correlate with the main stem values; and 3) the RAU from the upper petiole presented similar trends as the base of the stem but did not provide as reliable RAU estimation. The base of the stem is a reliable fraction to quantify soybean RAU while simplifying dry mass collection. The upper petiole fraction did not estimate RAU accurately, but it could differentiate contrasting N fixation levels. [ABSTRACT FROM AUTHOR]

• 'Paulsen 1103' presented lower K m and C min values. • Roots morphological parameters and kinetic parameters are highly related. • Grapevine rootstocks presenting more developed root systems have lower C min. • V max , K m and C min are good parameters for grapevine rootstock selection. Grapevine rootstocks are selected according to graft compatibility, pathogen tolerance and water stress. However, morphological and kinetic parameters of nutrient absorption, such as nitrate (NO 3 −) and ammonium (NH 4 +), usually are not considered. The study aimed to select, based on morphological and kinetic absorption parameters, grapevine rootstocks with greater efficiency of N-forms absorption. The study was performed with two grapevine rootstocks ('Paulsen 1103' and 'Magnolia'), grown in Hoagland nutrient solution in a greenhouse. After 21 d, they were placed in 0.05 mol L-1 CaSO 4 solution for 20 d to exhaust nutrient internal reserves. The rootstock with highest NO 3 − and NH 4 + uptake efficiency was 'Paulsen 1103', since it presented lower C min and K m values in the two N forms, allowing N extraction by roots, even in low concentrations in solution, due to the higher transporter affinity for NO 3 − and NH 4 + in roots from rootstock. 'Paulsen 1103' rootstock also presented better photosynthetic performance and root development, collaborating for greater growth and mass production than 'Magnolia' rootstock. On the other hand, 'Magnolia' rootstock showed higher NO 3 − and NH 4 + C min and K m values than 'Paulsen' rootstock, which shows lower transporters affinity for these ions. Results demonstrate the importance of the use of NO 3 − and NH 4 + uptake kinetic parameters in grapevine rootstock selection programs, since these may serve as indicator of plant's ability to absorb NO 3 − and NH 4 + in low concentrations. [ABSTRACT FROM AUTHOR]