Topdressing Nitrogen Fertilization Research Articles

Resistance identification and nitrogen management of wheat under late spring coldness

AbstractLate spring coldness has a profound impact on yield and quality of wheat (Triticum aestivum), the reasonable fertilization management significantly improved yield, quality, and cold resistance of plants. Here, 10 predominant wheat varieties cultivated in the Huang‐Huai‐Hai region were selected to investigate the detrimental influence mechanism of late spring coldness on wheat growth and screen three varieties with a strong resistance to coldness. Additionally, under late spring coldness, the three varieties were applied with varying ratios of base to topdressing nitrogen fertilizer to investigate the consequences on the establishment of population structure and subsequent formation of yield and quality. The results showed that late spring coldness exerted severely detrimental effect on wheat organs development, including the increased occurrence of dead tillers, elevated mortality of young spikes, and significant decrease kernels. However, compared to N1 treatment (a nitrogen fertilizer distribution of 100% base+0% jointing+0% booting), the N2 treatment (50% base+50% jointing+0% booting) exhibited favorable outcomes under late spring coldness, such as the decreased basic seedlings and tillers, increased flag leaf area, and leaf area index, contributing to the higher spike number, grain number, and 1000‐kernel weight. Ultimately, the grain yields of Jinan 17, Huaimai 28, and Yan'nong 5158 reached their maximum values, with a 23.5%, 10.6%, and 24.2% increase, respectively, and the membership function analysis confirmed the most favorable effect of N2 treatment. These findings underscore the appropriately increased ration of topdressing nitrogen fertilizer during late spring coldness as a prerequisite for achieving both high yield and good quality of wheat.

Alta densidade de plantas de cebola pode aumentar a demanda por nitrogênio?

ABSTRACT An adequate N supply is essential for plant growth, and changing plant density increases nitrogen demand. The objective of this work was to evaluate the effect of top-dressing nitrogen fertilization on quality and yield of onions grown under three plant densities. The experiment was conducted from June to October, in Oratórios, state of Minas Gerais, Brazil, using the hybrid Superex. A randomized block experimental design was used, with a split-plot arrangement and four replications. N rates (0, 60, 120, and 240 kg ha-1) were evaluated in the plots and plant densities (40 plants m-2 - one seedling per cell; 80 plants m-2 - two seedlings per cell; and 120 plants m-2 - three seedlings per cell) were evaluated in the subplots. The yield found for the treatment with 80 plants m-2 and 171 kg ha-1 of N was 51.28 Mg ha-1 of marketable bulbs, with approximately 75% class 3 and 17% class 4 bulbs. Bulb weight decreased with increasing plant density. Top-dressing nitrogen fertilization increases the quality and yield of onions, regardless of the plant density. The highest yield was found when using 80 plants m-2 and 240 kg ha-1 of N. A density of 80 plants m-2 (two seedlings per cell) and 171 kg ha-1 of N is recommended when intending to obtain class 3 and 4 bulbs.

PLANT ARRANGEMENT AND NITROGEN FERTILIZATION IN GRAIN SORGHUM PRODUCTION

The appropriate arrangement of sorghum plants combined with the supply of nutrients increases grain yield. In this context, the objective was to evaluate the agronomic performance of grain sorghum grown under different plant arrangements and nitrogen fertilization levels. Experiments were carried out in Rio Verde and Montividiu in a 3 x 2 factorial randomized completely block design with six replications, with three spacing between rows (reduced, traditional and double row) and the use or not of 90 kg ha-1 topdressing nitrogen. There was a beneficial effect of topdressing nitrogen fertilization on grain yield when sorghum was grown in double rows in both locations, and for the reduced arrangement in Montividiu. However, the effect of topdressing nitrogen fertilization on grain yield in the traditional arrangement was not found. The dry shoot biomass of sorghum plants increased with nitrogen fertilization in Montividiu. The arrangement or topdressing nitrogen fertilization did not influence the thousand-grain weight of Sorghum.

Response of early-cycle common bean cultivars with carioca, black and speckled grains to top-dressing nitrogen fertilization

The aim was to evaluate the agronomic and qualitative attributes of early-cycle common bean cultivars with different grains types grains in response to top-dressing nitrogen (N) doses. The experiment was carried out using a randomized block design, in a split-plot scheme, with 4 replicates. The plots consisted of the cultivars IAC Nuance, IAC 1849 Polaco and IAC Veloz, with speckled, Carioca and black grains, respectively. The subplots were formed by N doses applied as top-dressing: 0 kg ha-1, 60 kg ha-1 (applied in the stage of third trifoliate leaf), 120 kg ha-1 (1/2 applied at third trifoliate leaf stage + 1/2 applied at the floral bud stage) and 180 kg ha-1 (1/3 applied at the first trifoliate leaf stage + 1/3 applied at the third trifoliate leaf stage + 1/3 applied at the floral bud stage). IAC Veloz stood out for grain yield, showing the highest grain yield in the lowest N doses, being classified as efficient to the use of N. The cultivars IAC Nuance and IAC 1849 Polaco reached maximum yields with 155 and 163 kg ha-1 of N. The IAC Nuance was the most responsive, increasing grain yield by up to 25.3% due to nitrogen fertilization. Increasing N doses applied as top-dressing increased the sieve yield and crude protein content of the common bean cultivars, with IAC Nuance standing out. The cultivars showed good grain quality, and IAC 1849 Polaco and IAC Veloz had the shortest cooking time and IAC Veloz also had the fastest hydration.

Application of New-Generation Growth Regulators and Topdressing Nitrogen Fertilizers Increases Improver Winter Wheat Yield and Grain Quality in South Russia

The need for effective nutrient management is crucial for optimizing wheat production and increasing the plant’s ability to tolerate different environmental stresses. In this study, we assessed the influence of new-generation PGRs and foliar topdressing nitrogen fertilizer and their interactive effects on wheat yield and quality parameters of grain and flour. A three-year field experiment was conducted on the dark chestnut soil of the Rostov region. We estimated the effect of foliar topdressing liquid nitrogen fertilizer on consumption rates of N32 (N32), N64 (N32 + N32), and N96 (N32 + N32 + N32), as well as new-generation plant growth regulators (PGRs), namely, Zirkon, Silk, and Albit, on the productivity and grain quality of winter wheat Tarasovskaya 70. The results of the experiments indicate that the highest average grain yield over three years was 5.34 t/ha−1 with the application of N96 (N32 + N32 + N32) and Albit PGR. In 2020, due to favorable weather conditions, the greatest grain yield was attained at 6.27 t/ha−1 for N96 (N32 + N32 + N32) and Albit PGR. The highest grain quality with the greatest gluten content >28% was obtained when N96 (N32 + N32 + N32) and PGRs were applied. According to the results, using N96 (N32 + N32 + N32) and PGRs made it possible to obtain “valuable” grain in terms of quality, which is suitable for the production of premium flour. The beneficial interactive effects of N application rates and PGRs on winter wheat yield and quality parameters are worthy of further investigation.

The Starch Physicochemical Properties between Superior and Inferior Grains of Japonica Rice under Panicle Nitrogen Fertilizer Determine the Difference in Eating Quality.

Nitrogen fertilizer is essential for rice growth and development, and topdressing nitrogen fertilizer at panicle stage has a huge impact on rice grain quality. However, the effect of panicle nitrogen fertilizer (PNF) on starch physicochemical properties and fine structure remain unclear. In this study, four PNF levels (0, 60, 120, 180 kg N ha−1) were grown with the same basal and tiller fertilizer (150 kg N ha−1). The starch physicochemical properties, fine structure, texture properties and eating quality of two japonica rice were determined. We found that the content of total protein, crude fat and amylose between superior and inferior grains were significantly different. Compared with inferior grains, superior grains had low relative crystallinity, good pasting characteristics and outstanding eating quality. With the increase of nitrogen application rates, the starch volume mean diameter was lower; the average chain length of amylopectin was longer; and the relative crystallinity of starch was higher. The changes above in starch structure resulted in an increase in starch solubility, swelling power and gelatinization enthalpy, and led to a decrease in retrogradation enthalpy, retrogradation percentage and pasting viscosity, consequently contributing to the increase in hardness and stickiness of rice and the deterioration of taste value. These results indicated that topdressing PNF lengthened the amylopectin chain, decreased starch granule size, enhanced crystallization stability and increased gelatinization enthalpy, which were the direct reasons for the deterioration of cooking and eating quality.

An economic and viable approach to improve wheat quality in Qinghai–Tibetan Plateau, China

Wheat flour products are the main dietary component of the Qinghai–Tibetan Plateau (QTP) population in China. However, the high altitude restricts the local wheat quality and quantity, and the applied nitrogen rate is higher than the optimal rate for wheat planting. In this study, we considered whether reducing the amount of nitrogen fertilizer and introducing the superior varieties from the North China Plain (NCP) are viable ways to increase the wheat quality and quantity in the QTP. Three and four winter wheat cultivars from QTP and NCP, respectively, were planted in Lhasa at an altitude of 3 647 m with reduced topdressing nitrogen application at the jointing stage. The wheat from NCP exhibited higher grain hardness index and test weight, and better flour and dough quality. Reducing the topdressing nitrogen fertilizer from 135 to 75 kg N ha−1 at the jointing stage (with the same basal fertilization of 105 kg N ha−1) did not significantly (P<0.05) affect the grain yield, grain quality, flour quality or dough quality in any of the cultivars. In summary, introducing high-quality winter wheat varieties from the NCP to the Lhasa plateau is a viable way to enhance the wheat supply and quality in the QTP. Reducing a certain amount of the nitrogen fertilizer is an economic and feasible approach for the QTP region.

Productivity of main stem and tillers of rice as a function of nitrogen fertilization fractionation

The objective of this work was to evaluate the contribution of the main stem and tillers on the grain yield of irrigated rice, and on the physiological quality of the seeds as a function of fractionation of topdressing nitrogen fertilization. The experiment was performed in the field, at the 2016-2017 and 2017-2018 growing seasons. The treatments consisted of five nitrogen (N) topdress fractionations 50% of the rate at V3, and 50% at R0; 67% at V3, and 33% at R0; 60% at V3, 20% at V6, and 20% at R0, 100% at V3, and a control without N topdress application. The main stem panicle, and each tiller class were harvested, and grain yield (GY), yield components and physiological seed quality were evaluated. Grain yield and physiological seed quality are influenced by the panicle classes, being higher in the main stem panicle. The N fractionations of 67% at V3 and 33% at R0; 60% at V3, 20% at V6 and 20% at R0 and 100% at V3, promote higher GY and number of grains per panicle. The thousand grains mass, spikelet sterility, the physiological quality of seeds are not influenced by the topdressing nitrogen fertilization fractionation.

Bioinoculation methods compared to topdressing nitrogen fertilization in soybean

Inoculation with Bradyrhizobium is a viable biological tool for the agricultural production system. The objective of the work was to evaluate methods of inoculation of Bradyrhizobium and fertilization with N in cover. The treatments were carried out in a 2 × 3 factorial scheme, with or without application of N in cover and three inoculation methods. The N dose applied in cover was 60 kg ha−1, at 30 days after sowing, using urea. The experimental design was in randomized blocks with four replications. The data were submitted to analysis of variance and the means compared by the Tukey test at 5%. It is concluded that nitrogen fertilizers are unnecessary. There was no difference in productivity, mass of a thousand grains, macro and micronutrient contents in leaves with N in the cover. Bradyrhizobium in the seeds and in the sowing furrow provided higher soybean (Glycine max (L.) Merrill) productivity.

Optimal management of nitrogen fertilizer in the main rice crop and its carrying-over effect on ratoon rice under mechanized cultivation in Southeast China

This study attempted to clarify the carrying-over effect of different nitrogen treatments applied to the main crop on the crop population growth and yield formation of ratoon rice under mechanized cultivation in Southeast China. Based on the constant total nitrogen application amounts (225.00 kg ha−1) in the main crop, an experiment with different ratios of basal and topdressing nitrogen fertilizer (the ratio of basal fertilizer:primary tillering fertilizer:secondary tillering fertilizer:booting fertilizer at 3:1:2:4 (N1), 3:2:1:4 (N2), 3:3:0:4 (N3), and 4:3:0:3 (N4), respectively, and a control without nitrogen treatment (N0)) was set up across two consecutive years in field using hybrid rice variety Yongyou 1540 as the test materials. The results showed that the total tiller number and effective tillering percentage increased in the main crop under the N1 treatment, more nitrogen fertilizer applied in late growth stage of the main crop, and its effective tillering percentage of the main crop was the highest at up to 70.18%, which was 9.15% higher than that of conventional fertilization treatment (N4), more nitrogen fertilizer applied in early growth stage of the main crop. The same tendency was observed in leaf area index (LAI) value of the main crop and its subsequent ratoon rice, which were 16.52 and 29.87% higher, respectively, in the N1 treatment than that in the N4 treatment at the full heading stage. The same was true in the case of the transport rates of stem and sheath dry mater and the canopy light interception rates in both the main and its ratoon crops. The transport rate of stem and sheath in main crop rice under N1 treatment increased by 50.57% compared with N4 treatment. The canopy light interception rate of N1 treatment increased by 5.07% compared with N4 treatment at the full heading stage of the ratoon crop. Therefore, the total actual yield was the highest in the main and its ratoon crops under N1 treatment, averaging 17 351.23 kg ha−1 in two-year trials, which was 23.00% higher than that in the conventional fertilization treatment (N4). The results showed that appropriate nitrogen treatment was able to produce a good crop stand in the main crop, which was essential for producing a good ratoon crop population and high yield especially under mechanized cultivation with low stubble height of the main crop. The study suggested that shifting the proper nitrogen application amounts to the late growth stage of the main crop, such as N1 treatment, not only had a higher productive effect on ensuring the yield of the main crop, but also had a positive effect on the axillary bud sprouts from the stubbles for ratoon rice, resulting in an increased percentage of productive panicles and achieving the goal of one planting with two good harvests under the conditions of our study.

Do the previous crop and top-dressing nitrogen fertilization change the yield and physiological and sanitary quality of common bean seeds?

Abstract: The aim was to evaluate the effects of previous crop and top-dressing nitrogen fertilization on the yield and physiological and sanitary quality of common bean seeds. The design used was in randomized blocks in a split-plot scheme, with four replications. The plots were represented by three previous crops (sole maize, maize + Urochloa ruziziensis and sole U. ruziziensis), preceding common bean. The subplots consisted of N doses (urea) applied as top-dressing (0, 40, 80, 120 and 160 kg N.ha-1) when the common bean had four expanded leaves. Physiological quality and sanitary quality of the seeds were evaluated through germination tests, first count, emergence speed index, accelerated aging, seedling emergence in the field and pathogen incidence, in addition to crude protein content, 100-seed weight and yield. The study factors did not interfere in the sanitary quality of the seeds. Under U. ruziziensis straw, the highest seed yield was obtained with the N dose of 115 kg.ha-1, while under sole maize and intercropping straw, the increase in yield was linear. Previous crop with U. ruziziensis, whether cultivated as sole crop or intercropped with maize, promotes greater physiological quality of common bean seeds, while top-dressing nitrogen fertilization does not interfere with quality, weight and protein content of the seeds.

Agronomic performance of maize (Zea mays L.) genotypes under Azospirillum brasilense application and mineral fertilization

&#x0D; Maize has a high nitrogen demand; as a result, more sustainable alternatives are needed to reduce demand for mineral fertilizers. This study aimed to evaluate and characterize the agronomic performance of maize genotypes submitted to topdressing nitrogen fertilization and inoculation with Azospirillum brasilense. An experiment was conducted in the second season of 2017, in Jaboticabal-SP (Brazil), using 48 maize genotypes in a randomized block design. Treatments consisted of: 1) application of 140 kg ha-1 nitrogen, using urea as mineral fertilizer; 2) A. brasilense inoculation via soil, at a rate of 600 mL ha-1, as biological fertilization. Grain yield and agronomic traits were evaluated. The data were subjected to analysis of variance (F-Test), means were compared by Scott-Knott test at 5% probability, and multivariate statistical analysis was performed by principal component analysis. A. brasilense inoculation via soil has a significant effect on female flowering, on the interaction between genotype versus N supply for Fusarium spp., and increases the maize grain yield; however, the responses of agronomic attributes vary with genotype.&#x0D; Highlights&#x0D; &#x0D; The inoculation with Azospirillum brasilense via soil increases maize grain yield, becoming viable and more sustainable alternative in the supply of nitrogen.&#x0D; The choice of the genotypes is an essential fator for the sucessful use of Azospirillum brasilense application or mineral fertilization, because the responses of agronomic attributes vary with the genotype.&#x0D; The most contrasting genotypes can be recombined in new stages of crossbreeding and selection, aiming at obtaining genotypes with greater yield potential in the use of Azospirillum brasilense inoculation.&#x0D; Further studies are needed to better understand this technology under conditions with different genotypes, soils and production systems.&#x0D;

Crop succession and split-application of nitrogen effects on common bean yield in short no-tillage system

AbstractEvaluating the effects of crop successions in no-tillage system (NTS) is essential for the correct recommendation of agronomic practices, such as top-dressing nitrogen fertilization. The aim was to evaluate the effect of the crop succession and the splitting of top-dressing N fertilization on the agronomic performance and economic viability of common bean crop. The experiment was conducted in southeastern Brazil for two agricultural seasons in an area under NTS, using a split-plot in randomized complete block design. The plots represented three cropping successions (maize in sole crop, maize intercropped with Urochloa ruziziensis and U. ruziziensis in sole crop) and the subplots composed of ten combinations of splitting of top-dressing N, at the stages V3, V4 and R5 of the common bean crop. In relation to the single application of the N dose of 90 kg ha−1, the common bean had higher response as a function of the N splitting schemes adopted, regardless of the previous cropping succession. The cropping successions evaluated did not interfere with the seed yield of common bean as subsequent crop, even at the beginning of the establishment of NTS. To obtain higher seed yield and economic viability, the N dose of 90 kg ha−1 indicated for the crop must be split and applied among the phenological stages V3, V4 and R5.

Topdressing nitrogen fertilization associated with trinexapac-ethyl on industrial quality of oat grains

Nitrogen fertilization, besides increasing productivity, can favor the production of well-formed, large, and heavy grains, which are traits valued by the oat processing industry. However, high nitrogen (N) doses may lead to plant lodging, which could be solved by using growth retardant. This study aimed to evaluate the industrial quality of white oat grains cultivated under different nitrogen doses and associated with the growth retardant trinexapac-ethyl in two growing environments. Experiments were conducted in Londrina and Mauá da Serra, PR, Brazil, using the cultivar IPR Afrodite in a randomized block design in a 4 × 2 factorial scheme and four replications. Treatments consisted of four topdressing N doses (0, 30, 60, and 90 kg ha−1) and the application or not of growth retardant. Thousand-grain weight, hectoliter weight, grain index greater than two millimeters, peeling index, and industrial grain yield were evaluated. The effect of N fertilization and growth retardant on the industrial quality of white oat grains depends on the characteristics of the growing environment. The trinexapac-ethyl application reduces grain quality in Londrina and Mauá da Serra. However, the industrial quality of grains is high in both growing environments when the growth retardant is associated with nitrogen doses.

Co-inoculation and inoculation methods of plant growth-promoting bacteria in wheat yield performance

Several studies have reported the beneficial effects of inoculation of Azospirillum brasilense in wheat, but only a few of them have related the co-inoculation of A. brasilense and Rhizobium sp. and the evaluation of different inoculation methods. This study aimed i) to verify the efficiency of plant growth-promoting bacteria (PGPB) in subtropical environments, ii) to verify the efficiency of co-inoculation of A. brasilense and Rhizobium sp., and iii) to verify the efficiency of the management of different inoculation methods in the wheat crop. The experiments were carried out in Londrina and Apucarana, State of Paraná, Brazil, under a complete randomized block design, with four replications and nine treatments: T1) absence of nitrogen (N) topdressing, T2) 30 kg ha−1 of N topdressing, T3) 60 kg ha−1 of N topdressing, T4) A. brasilense Ab-V5 in the seeds, T5) A. brasilense Ab-V5 in post-emergence, T6) A. brasilense Ab-V5 + Rhizobium sp. 53GRM1 in the seeds, T7) A. brasilense Ab-V5 + Rhizobium sp. 53GRM1 in post-emergence, T8) commercial inoculant (A. brasilense Ab-V5 + Ab-V6) in the seeds, and T9) commercial inoculant (A. brasilense Ab-V5 + Ab-V6) in post-emergence. The number of ears per linear meter, number of spikelets, number of grains per spikelet, number of grains per ear, thousand-grain weight, number of spikelets to ears ratio, leaf nitrogen content, and grain yield were evaluated. Leaf N content and yield components showed no alterations due to the inoculation and co-inoculation performed both in the seed and in the post-emergence of seedlings. Treatments T3, T7, and T9 showed the highest means of grain yield (2077.50, 1743.12, and 1660.62 kg ha−1, respectively), demonstrating that co-inoculation with A. brasilense Ab-V5 + Rhizobium sp. 53GRM1 and inoculation with A. brasilense Ab-V5 + Ab-V6, both in post-emergence of seedlings, have the potential to replace the topdressing nitrogen fertilization in wheat.

Fodder Yield, Quality and Growth of Chia (Salvia hispanica L.) as Affected by Sowing Density and Top-Dressing Nitrogen Fertilization

Chia (Salvia hispanica L.) seeds are considered a superfood, but research on vegetative biomass uses is scarce. We conducted a two-year trial under the hypothesis that short-day flowering black chia would provide quality forage at high latitudes and tested sowing density (D1 = 125, D2 = 25, D3 = 8 and D4 = 4 plants m−2) and top-dressing N fertilization (N = 0, N = 20 kg ha−1) at three stages (EV = early vegetative, LV = late vegetative and EF = early flowering). Forage yield reached 9.0 and 5.64 t ha-1 of total and 2.07 and 1.56 t ha−1 of leaf dry mass at EF in 2013 and 2014, respectively. High plant density corresponded to higher biomass but to lower plant relative growth rate, stem diameter, branching, proportion of leaves and lipid and crude protein content. Crude protein declined from 18% at EV to about 8% at EF and was lower in D1 than in D4. Lipids ranged between 33.83 g kg−1 (D4, EV) and 17.34 g kg−1 (D1, EF) (p &lt; 0.005). N topdressing affected forage quality but not yield. Alpha-linolenic acid was the most abundant fatty acid (FA) (608 g kg−1 FA at EV). The long vegetative growth of short-day flowering chia in southern Europe is favorable to fodder production, and management should be optimized by seeking balance between growth rate and stand density while optimizing vegetative stage growth for the highest forage quality.

AGRONOMIC PERFORMANCE OF MAIZE UNDER Azospirillum brasilense INOCULATION AND TOP-DRESSING NITROGEN FERTILIZATION

Maize inoculation with bacteria of the genus Azospirillum can reduce the consumption of nitrogen fertilizers to obtain maximum grain yield. In this context, the aim was to evaluate the effect of inoculation with Azospirillum brasilense associated with nitrogen fertilization on the maize agronomic performance. A randomized block design was used in a split-plot scheme with four replicates. Four inoculation managements with Azospirillum brasilense (T0 - control without inoculation; TC2 - seed box inoculation, 200x108 viable cells ha-1; TC3 - seed box inoculation, 400x108 viable cells ha-1; TS1 - previous inoculation of the seeds, 600x108 viable cells ha-1) associated with four top-dressing N doses (0, 60, 120 and 180 kg ha-1), applied at maize stage V6 by urea. Inoculation with Azospirillum brasilense associated with top-dressing nitrogen fertilization increases the number of grain rows per ear, number of grains per row, number of grains per ear and grain yield of maize, mainly due to its positive effects on plant nutrition. Managements with seed box inoculation with 400x108 viable cells per ha (TC3) and inoculation in seed pre-treatment (TS1) are the most recommended for maize.

Effects of integration of micro-sprinkler irrigation and nitrogen on growth and development of winter wheat and water and fertilizer use efficiency

Under the same irrigation amount and nitrogen application rate and after the corn stalks being returned to the field in the wheat-corn crop rotation area, we examined the effects of the integrated water and nitrogen mode of micro-sprinkler irrigation on the growth and development and water and fertilizer use efficiency of winter wheat. In 2016-2018, we conducted a two-year field experiment with six types of micro-sprinkler irrigation water and nitrogen integration modes and seven treatments during the growth period, and investigated the population dynamics, dry matter accumulation transfer during the filling period, and nutrient accumulation during the mature period. There were three modes of irrigation, W1(overwintering water + jointing water + grouting water, 600 m3·hm-2 for each), W2(overwintering water + regreening water + jointing water + grouting water, each for 450 m3·hm-2), and W3(600 m3·hm-2 each for overwintering water and jointing water, and 300 m3·hm-2 each for regreening water and grouting water); two modes of nitrogen application, N1(basic nitrogen application 60% + jointing water nitrogen topdressing 40%) and N2 (basic nitrogen application 60% + jointing water nitrogen topdressing 30% + grouting water nitrogen topdressing 10%); with no fertilization under W1 as control (CK). The results showed that: 1) The amount of overwintering water irrigation increased from 450 m3·hm-2to 600 m3·hm-2, which was beneficial to the total number of both stems and panicles in the overwintering period and consequently to yield. Irrigation in the regreening stage increased the total number of stems at the jointing stage, but with limited effect on the number of panicles. Applying more nitrogen at the jointing stage increased the number of stems per plant, but decreased that of panicles. 2) Four times of irrigation (W2 and W3) during the growth period, combined with nitrogen (N2) in the jointing and filling phases, were conducive to the accumulation of dry matter during the filling period, increasing the number of grains per spike and 1000-grain weight, thereby increasing yield. 3) Compared with the three times of irrigation treatment during the growth period, water consumption and absorption of nitrogen, phosphorus and potassium under the four times of irrigation treatment were increased, and water and fertilizer use efficiency was improved. In W2 and W3 under the treatment of four times irrigation, water consumption of N2 during the growth period was lower than N1, absorption of nitrogen, phosphorus, and potassium were higher than N1, and the irrigation and utilization of nitrogen, phosphorus and potassium were significantly improved, of which W3N2 had the best effect. Therefore, W3N2 treatment (sowing winter wheat after returning corn stalks to the field, irrigating four times during the growth period of micro-sprinkler irrigation, increasing the amount of overwintering water and jointing water irrigation to 600 m3·hm-2, combined with jointing water and filling water topdressing nitrogen fertilizer) increased spike number and 1000-grain weight of wheat andincreased yield, with the highest water and fertilizer use efficiency. It was the best water and nitrogen management mode for the integration of micro-sprinkler irrigation and water and fertilizer for winter wheat in southern Shanxi.

Efficiency and Response to Nitrogen Use in Maize Genotypes for Silage Production in Tropical Climate

Aims: This study aimed to select efficient and responsive maize genotypes to the use of nitrogen for silage.&#x0D; Study Design: The experimental design was randomized blocks in a 2 x 11 factorial scheme, the first factor being two nitrogen levels: 165 kg ha-1 of N and 15 kg ha-1 of N, and second factor eleven maize genotypes: BRS 3046, M 274, AG 8088PRO2, ANHEMBI, PR 27D28, AG 1051, P33-16, P33-11, P29-M12, P36-19, and P40-8.&#x0D; Place and Duration of Study: The experiment was carried out in the 2017/18 harvest at Sítio Vitória (8º18'32" S, 50º36'58" W), located in the municipality of Santa Maria das Barreiras, southern region of Pará state, Brazil.&#x0D; Methodology: Sowing fertilization was performed in the furrow with 300 kg ha-1 of NPK 5-25-15. Topdressing nitrogen fertilization was performed only at high N, having as source urea (45% N) at a dose of 150 kg ha-1 of N. Parceled in stages V4 and V8. The shoot fresh mass was evaluated at stages R4 and R5, with the cut performed 20 cm from the soil.&#x0D; Results: The highest shoots fresh masses were obtained in treatments with high use of N, with a general mean of 628 g plant-1. The mean response of 1.87 g of plants per kg of N applied. Genotypes M 274, AG 8088PRO2, PR 27D28, AG 1051 and P 36-19 were efficient to use N. Genotypes AG 8088PRO2, PR 27D28, P29-M12, and P 36-19 were classified as responsive to N application.&#x0D; Conclusion: Genotypes AG 8088PRO2, PR 27D28 and P36-19 were efficient in use and responsive to nitrogen application. And they are recommended for cultivation with low and high technological level.

Nitrogen fertilization management in white oat using spectral indices

ABSTRACT Remote sensing techniques have been considered a new technology in worldwide agriculture for diagnosing the plant nutritional demand. Fertilizer management efficiency is a goal to be achieved, and modern tools based on remote sensing are promising for monitoring the crop needs. This study aimed to evaluate the agronomic performance and relative economic return of white oat under nitrogen rates, as well as to verify whether the normalized difference vegetation index (NDVI) and leaf chlorophyll index (LCI) could be used for topdressing nitrogen fertilization management, in white oat. Treatments consisted of five topdressing nitrogen fertilization strategies: T1 - 160 kg ha-1 (reference rate); T2 - 90 kg ha-1 (recommended rate); T3 - 60 kg ha-1 (economic rate); T4 - 30 kg ha-1 (when NDVI &lt; 90 % of T1); and T5 - 30 kg ha-1 (when LCI &lt; 90 % of T1). The white oat did not respond to the topdressing nitrogen fertilization. Its temporal monitoring using spectral indices allowed dispensing the topdressing nitrogen fertilization without reducing the grain and biomass yields and the leaf nitrogen content, when compared to the recommended management (90 kg ha-1 of N as topdressing), with no differences between the evaluated spectral indices. Thus, both the NDVI and LCI spectral indices are promising tools for the topdressing nitrogen fertilization management in the white oat crop.