Shoot Dry Matter Production Research Articles

Effect of Na2SO4 Application on the Growth, Yield and Cd uptake of Wheat

Objective: Durum wheat accumulates more cadmium (Cd) in the grain than bread wheat. The aim of this study was to determine the effect of Na2SO4 salt on Cd uptake in wheat grain. Material and Method: The experiment was conducted by using durum wheat cultivar (Triticum durum, cvs. Balcalı-2000) under greenhouse condition. After 43 day of growth in the greenhouse, the shoots were harvested and dried at 70 ºC for determination of shoot dry matter production. It was also analyzed Cd concentration in shoot. The concentration of shoot Cd was measured by (ICP-OES, Varian, Australia). Results: Our results conclude that soil salinity increases Cd accumulation in the shoot even when soil Cd rates are very low. Furthermore, salinity in Cd-contaminated soils may accelerate cadmium transport to the shoot. Conclusions: The findings of this study revealed that shoot Cd concentration increased with increasing applied Cd and Na2SO4 rates.

Hybrid passive cooling and heating system for Mediterranean greenhouses. Microclimate and sweet pepper crop response

The microclimate of low-tech, unheated greenhouses in Mediterranean areas, associated with the local outdoor climate, is often outside the optimal range for most horticultural crops during both the warm and cold growing season. The use of a new hybrid system of passive cooling (evaporative screens) and heating (water-filled sleeves), in combination with an internal movable shading/thermal screen, was evaluated on a representative summer transplanted sweet pepper crop grown in perlite growing bags. The experiment was carried out in two identical greenhouses at the IFAPA La Mojonera research center in Almeria (SE Spain): one greenhouse with the hybrid passive system of cooling and heating, in combination with a shading/thermal screen, and another (reference greenhouse) using common local greenhouse climate management practices. Evaporative screens, in combination with a movable shading screen, improved the greenhouse climate, in particular the air vapour pressure deficit, and increased the leaf area index in the early stages of the crop, which, in turn, increased the early production of leaf and shoot dry matter and marketable fruit, compared to the reference greenhouse crop. In addition, the combined use of water-filled sleeves and thermal screen during the cold growth period increased greenhouse air temperatures, especially at night, and substrate temperatures. Overall, by improving the greenhouse microclimate during the warm and cold growth periods, the hybrid passive cooling/heating system, in combination with the shading/thermal screen, increased the marketable yield of a summer transplanted sweet pepper crop by 25 %, reduced the irrigation water supply by 8 %, and improved the irrigation water use efficiency by 20 % (including the potential water used to humidify the evaporative screens).

Biomass Production and Partitioning Response of Coffee (Arabica Coffea L.) Seedlings to Different Poly-Bag Size and Biochar Based Media Preparations

Nursery experiment was conducted at Awada Agricultural Research Sub-Center, to investigate dry matter production and it’s partitioning into above and below ground parts of Arabica coffee seedlings treated under different ratio of biochar to top soil based media preparations and different poly bag size used to raise the seedlings. The treatment combinations with four levels of pot size (width by height) (7cm x13cm, 10cm x 16cm, 13cmx19cm and 16cmx 22cm) and five levels of biochar to top soil ratio (0:1, 1:1, 1:2, 1:3, 1:4) by (v/v) were used for the treatment were factorially combined and laid out in a randomized complete block design with three replications. Results showed that the main effect of poly bag size and biochar to top soil ratio of media preparation were significantly (P<0.01) affect leaf, shoot, root and total dry matter production and shoot to root ratio of coffee seedlings. The highest total dry weight (6.83g) was recorded from pot size of 16x22cm interacted with one to three (1:3) biochar to topsoil ratio followed by (6.57g) harvested from pot size of 13cmx19cm interacted with one to four (1:4) biochar to top soil ratio. Similarly, the root to shoot ratio of coffee seedlings was significantly (P = 0.017) affected by the combined effects of the two factors. Pot size 13cmx19cm interacted with one to four (1:4) biochar to top soil ratio exhibited the maximum (0.272g/g) RSR as compared to rest of growing media and all pot size interacted with one to four (1:4) biochar to top soil ratio have statically higher value similar to the largest value above mentioned parameters except shoot to root ratio. Thus, it is concluded that vigorous coffee seedlings with high dry matter content and optimum root to shoot distribution for better seedling production can be produced by optimum poly bag size of 13cmx19cm interacted with one to three (1:3) biochar to topsoil. But, further investigations should be continued under different media preparation for wider opportunities at different area coffee growing areas.

Genetic diversity and candidate genes for transient waterlogging tolerance in mungbean at the germination and seedling stages.

Mungbean [Vigna radiata var. radiata (L.) Wilczek] production in Asia is detrimentally affected by transient soil waterlogging caused by unseasonal and increasingly frequent extreme precipitation events. While mungbean exhibits sensitivity to waterlogging, there has been insufficient exploration of germplasm for waterlogging tolerance, as well as limited investigation into the genetic basis for tolerance to identify valuable loci. This research investigated the diversity of transient waterlogging tolerance in a mini-core germplasm collection of mungbean and identified candidate genes for adaptive traits of interest using genome-wide association studies (GWAS) at two critical stages of growth: germination and seedling stage (i.e., once the first trifoliate leaf had fully-expanded). In a temperature-controlled glasshouse, 292 genotypes were screened for tolerance after (i) 4 days of waterlogging followed by 7 days of recovery at the germination stage and (ii) 8 days of waterlogging followed by 7 days of recovery at the seedling stage. Tolerance was measured against drained controls. GWAS was conducted using 3,522 high-quality DArTseq-derived SNPs, revealing five significant associations with five phenotypic traits indicating improved tolerance. Waterlogging tolerance was positively correlated with the formation of adventitious roots and higher dry masses. FGGY carbohydrate kinase domain-containing protein was identified as a candidate gene for adventitious rooting and mRNA-uncharacterized LOC111241851, Caffeoyl-CoA O-methyltransferase At4g26220 and MORC family CW-type zinc finger protein 3 and zinc finger protein 2B genes for shoot, root, and total dry matter production. Moderate to high broad-sense heritability was exhibited for all phenotypic traits, including seed emergence (81%), adventitious rooting (56%), shoot dry mass (81%), root dry mass (79%) and SPAD chlorophyll content (70%). The heritability estimates, marker-trait associations, and identification of sources of waterlogging tolerant germplasm from this study demonstrate high potential for marker-assisted selection of tolerance traits to accelerate breeding of climate-resilient mungbean varieties.

Organic fertilization as a sustainable alternative in the production of bean varieties in the brazilian semiarid region

This study aimed to evaluate the effect of organic fertilization and the use of rock powder in different varieties of cowpea in an agroecological family farming system in a semi-arid region of Brazil. The design was in randomized blocks 4 blocks x 4 treatments (T1 - witness; T2 - 4.0 t ha-1 rock powder; T3 - 10 t ha-1 bovine manure + organic matter; and T4 - 4 t ha-1 rock powder + 2.1 t ha-1 organic compound) x 3 varieties. At 65 days, plant height (PH), stem diameter (SD), number of leaves (NL), leaf area (LA), and crop yield were evalueted: number of pods (NP), number of pods per plant (NPP), total seed weight (TSW), grain production (GP) and shoot dry matter production (SDMA). The creole variety Sedinha obtained better results in the development and yield of the crop, the organic compost was the most efficient for all varieties, the addition of rock powder did not result in significant effects compared to other treatments. This study highlights the potential for producing Creole seeds, in addition to demonstrating that organic fertilization is an efficient alternative, and reduces the use of chemical fertilizers contributing to the sustainable use of natural resources.

Response of peanut to foliar application of molybdenum and seed inoculation with Bradyrhizobium spp. in Cerrado region, Brazil

The adoption of sustainable technologies that optimize biological nitrogen fixation (BNF) by peanut crops is essential to improve plant growth and ensure high grain yield potential. A study was conducted to investigate the efficiency of inoculation with Bradyrhizobium spp. and foliar application of molybdenum (Mo) in improving the productive response of peanut crop (Arachis hypogaea L., cv. IAC Tatu ST) in moderately acidic sandy soil (pH 5.0) of the Cerrado region, Brazil during two growing seasons (2016/2017 and 2017/2018). Treatments consisted of uninoculated seeds (control) and inoculated with Bradyrhizobium spp. and foliar application of Mo at five rates (0, 25, 50, 100, and 150 g Mo ha−1). These treatments were arranged in a randomized block design in split plots with four replicates. Nodulation, shoot dry matter, leaf N concentration, and peanut grain yield were significantly high in plants inoculated with Bradyrhizobium spp. in both growing seasons. The grain yield increased by 13% and 12% with the inoculation of Bradyrhizobium spp. compared with non-inoculated plants in the 2016/2017 and 2017/2018 seasons, respectively. Plants fertilized with Mo showed higher root nodulation, leaf N concentration, and shoot dry matter production than control plants in both growing seasons. However, the crop grain yield was significantly high (24%) only in the 2016/2017 season in plants fertilized with Mo. The optimal rate of foliar Mo application in peanut plants cultivated in sandy soils varies from 80 to 100 g of Mo ha−1. Due to improved root nodulation, N uptake, plant growth, and higher crop grain yield, rhizobium inoculation and foliar application of Mo are sustainable agricultural practices that should be recommended for peanut growers.

Efficiency of absorption, translocation, and use of nitrogen by water-stressed coffee

Climate change and the expansion of agricultural lands to low-fertility soils have prompted studies on the effects of water and nutritional stress on nutrient uptake and use. This study aimed to evaluate the efficiency of absorption, translocation, and use of N in coffee cultivars under water stress (WS) and different N doses. The experiment was performed hydroponically and arranged in a 4 × 2 × 4 factorial randomized block design with three replications. These factors consisted of four coffee varieties, two N doses, and four levels of WS. At the end of the experiment, the dry matter production, N concentration, and N accumulation of plants, as well as nutritional efficiency indices were evaluated. The data were subjected to analysis of variance and regression. The results showed that in plants previously well-supplied with N, N stress induces greater allocation of dry matter in roots, mitigating the effects of subsequent water deficits on shoot dry matter production. Young Mundo Novo plants subjected to N stress followed by increasing water stress maintained a high utilization efficiency (UE). Young Acauã plants well-supplied with N, maintained their N utilization efficiency up to -1.6 MPa of water stress; however, when they were N starved, they underwent a drastic reduction in UE at potentials below -0.22 MPa.

Ammonium Fertilization Enhances Nutrient Uptake, Specifically Manganese and Zinc, and Growth of Maize in Unlimed and Limed Acidic Sandy Soil

Although NH4+ fertilization is known to acidify rhizosphere and enhance nutrient uptake, the effects on a nutrient-sufficient acidic soil amended with lime are not demonstrated. Thus, the influence of NH4+ fertilization of an unlimed and limed (3 g calcium carbonate per kg soil) acidic soil on the nutrient uptake and growth of maize was studied in comparison to NH4NO3 fertilization. The pH of limed rhizosphere soil was about two units higher than that of the unlimed soil. The maize plants were grown in pots under greenhouse conditions for about two months. The results showed that the pH of the NH4+-fertilized unlimed and limed soil was 0.54 and 0.15 units lower than the NH4NO3-fertilized soil. Liming negatively affected shoot and root dry matter production, whereas the NH4+-fertilized plants produced higher dry matter than the NH4NO3-fertilized plants, with significant difference of 28% in the limed soil only. Liming decreased Fe concentration in rhizosphere soil from 99 to 69 mg kg−1 and decreased plant-available Mn the most (71%), whereas the NH4+-fertilized unlimed and limed soil had 48% and 21% higher Mn concentration than the respective NH4NO3-fertilized soils. Similarly limed rhizosphere soil had 50% lower plant-available Zn concentration than the unlimed soil, and the NH4+-fertilized soil had an 8% higher Zn concentration than the NH4NO3-fertilized unlimed soil. The liming negatively affected P, K, Mn, and Zn concentrations and contents in maize shoot to a lower degree in the NH4+-fertilized soil, whereas the positive effect of NH4+ on the nutrient concentration and contents was vigorous in the unlimed soil than the limed soil. It is concluded that NH4+ fertilization could be beneficial in enhancing nutrient uptake and growth of maize in both acidic and alkaline soils, despite the higher inherent plant-available concentrations of the nutrient in soil.

Deficiencies of nitrogen, calcium, and micronutrients are the most limiting factors for growth and yield of smell pepper plants

Cultivation and commercialization of Capsicum pepper have great importance in Brazil. This work assessed the influence of omission of macro and micronutrients on the growth and mineral nutrition of sweet pepper plants (Capsicum chinense Jacquin). The research was carried out in a greenhouse with washed sand as substrate. The experimental design was completely randomized with five replications and eight treatments: complete (control), omission of N, P, K, Ca, Mg, S, and micronutrients (B, Cu, Fe, Mn and Zn). The plants were submitted to the treatments when they reached an average height of 20 cm and the nutrient solution was supplied by percolation in plastic pots and renewed every 15 days. Nutrients omission affected negatively plant growth as a whole. The omission of N, Ca, and micronutrients greatly reduced sweet pepper yield. The C. chinense plants presented the sequence by dry matter production of shoots and roots in descending order: COMP > OP > OS > OK > Omg > ON > Oca > OMicro.

Biochar alleviated the toxic effects of PVC microplastic in a soil-plant system by upregulating soil enzyme activities and microbial abundance

Plastics have become an emerging pollutant threatening the sustainability of agroecosystems and global food security. Biochar, a pro-ecosystem/negative carbon emission technology can be exploited as a circular approach for the conservation of plastics contaminated agricultural soils. However, relatively few studies have focused on the effects of biochar on plant growth and soil biochemical properties in a microplastic contaminated soil. This study investigated the effects of a cotton stalk (Gossypium hirsutum L.) biochar on plant growth, soil microbes, and enzyme activity in PVC microplastic (PVC-MPs) contaminated soil. Biochar amendment increased shoot dry matter production in PVC-MPs contaminated soil. However, PVC-MPs alone significantly reduced the soil urease and dehydrogenase activity, soil organic and microbial biomass carbon, bacterial/fungal community percentage, and their abundance (16S rRNA and 18S rRNA genes, respectively). Interestingly, biochar amendment with PVC-MPs significantly alleviated the hazardous effects. Principal component and redundancy analysis of the soil properties, bacterial 16S rRNA genes, and fungal ITS in the biochar-amended PVC-MPs treatments revealed that the observed traits formed an obvious cluster compared to non-biochar treatments. To sum up, this study indicated that PVC-MPs contamination was not benign, while biochar shielded the hazardous effects and sustained soil microbial functionality.

Low Nocturnal Temperature Alters Tomato Foliar and Root Phosphorus Fractions Allocation by Reducing Soil Phosphorus Availability

Low nocturnal temperature (LNT) is a major constraint for protected tomato production in China during winter and spring, which leads to tomato phosphorus (P) deficiency symptoms. The soil P fractions reflect soil P availability. The foliar and root P fractions reflect the adaptation strategies of tomatoes to LNT. However, the relationship between plant P fractions and soil P fractions under LNT is not well understood. Therefore, we conducted a 40-day indoor incubation experiment with four nocturnal temperatures (15, 12, 9 and 6 °C). Tomato growth status, plant P fractions and soil P fractions were determined. Then, structural equation model (SEM) was used to analyze the direct and/or indirect effects of LNT on soil P fractions, plant P fractions and tomato shoot dry weight (SDW). The results showed that LNT decreased soil P availability by decreasing soil labile P and increasing soil moderately labile P. The foliar inorganic P, metabolite P, nucleic acid P and residual P were decreased under 9 and 6 °C. The root nucleic acid P and lipid P were decreased, while metabolite P was increased under 9 and 6 °C. Tomato foliar and root P fraction allocation was directly influenced by the increase in soil moderately labile P, while the decline in SDW was directly influenced by the decrease in soil labile P. In conclusion, LNT affects tomato P fractions allocation by reducing soil P availability, which limits the shoot dry matter production in tomatoes.

Learning about the growing habits and reproductive strategy of Thinopyrum intermedium through the establishment of its critical nitrogen dilution curve

The perennial grain crop Thinopyrum intermedium can provide various ecosystem services and a dual production of grains and forage. Yet, to improve crop management, better knowledges of its physiological behavior and growing habits are required. The goal of this study was to characterize Th. intermedium nitrogen (N) requirements through the evaluation of its response to N fertilization and the subsequent determination of its critical nitrogen dilution curve (CNDC). A field experiment was implemented in Belgium during three growing seasons with various N fertilization schemes. Biomass of the different organs and their N contents were measured at specific phenological stages. To estimate the CNDC, a Bayesian hierarchical model was applied on the assembled dataset. The validity of the curve was assessed on an independent dataset including contrasted N situations. Globally, N fertilization had a positive impact on the dry matter (DM) of leaves, stems and ears (p-value<0.05). The aboveground biomass and N uptake were found maximum with fertilization comprised between 100 and 150 kg N/ha applied over the entire growing year. At grain harvest, total DM ranged from 7.0 to 16.4 t DM/ha for a fertilization strategy of 100 kg N/ha, depending upon the growing season. The N amount of the aboveground biomass was found to decrease during the second phase of the growing cycle. As observed with the proposed CNDC, the aerial N content tended to decrease with the evolution of growing stages and biomass accumulation. Through the low a-coefficient determined for the CNDC, it was confirmed that the crop had reduced need in terms of N nutrition. The reduced N requirements can be linked to the high N use efficiency and a potential resource-conservative strategy of the crop. This, combined with the observed decrease of the N uptake by the aboveground biomass during the second phase of growth, can be related to the long-term survival strategy of the crop. The latter requires substantial investments in perennial belowground structures coupled with reduced resource allocations to seeds. Our study has highlighted that Th. intermedium is able to reach a high shoot DM production with low N needs. Our proposed CNDC will be highly helpful to help define N requirements in various pedo-climatic environments and adjust accordingly the soil-crop management, among which the N fertilization. Ultimately, the low N requirements of Th. intermedium coupled with a high N use efficiency demonstrated that it could enhance agronomic and environmental benefits.

Genotypic differences in phosphate nutrition of barley (hordeum vulgare L.)

Phosphorus use by four genotypes of barley was studied at five phosphate levels in pot studies for 30 days. For all P levels, there were marked genotypic differences in the root, shoot and total dry matter accumulation and phosphorus use efficiency of shoots (PUE) (g shoot /mg plant in the shoot). There were significant genotypic differences in the root, shoot and total accumulation dry weight increased with increasing P levels. The magnitude of the increase resulting from phosphorus application of 125ppm P was 66.3%, 32.2% and 43.7% resp. compared with 0 ppm. Significant differences were observed in dry matter accumulation amongst barley genotypes, where the Rahan variety recorded the highest shoot and total dry matter at 125 ppm P (2.25 and 4.53 g/pot) resp. PUE was significantly influenced by P levels and by genotypes. Based on dry matter production of shoots at low P level, Rahan and M97 varieties recorded the highest PUE (0.75 and 0.72 g SDM/mg plant) resp.

Rice demands higher nitrogen fertilizer during grain filling stage under elevated atmospheric CO2 condition

An experiment was conducted in open top chamber (OTC) to determine the response of rice to elevated carbon dioxide (eCO2) under varying time of nitrogen (N) application. Rice was grown in OTC with 500 ppm CO2 (eCO2), 450 ppm CO2 (intermediate CO2, iCO2), ambient CO2 (aCO2) and open field (OF, 380 ppm CO2). The timings of N application were N1 = 1/3rd N at early tillering (ET) + 1/3rd at active tillering (AT) + 1/3rd before panicle initiation (PI) stage, N2 = 1/3rd N at ET + 1/3rd before PI + 1/3rd at booting stage (BS), and N3 = 1/3rd N at ET + 1/3rd before PI + 1/3rd at flowering stage (FS). The results revealed that photosynthesis (Pn), shoot and root dry matter (SDM and RDM) production, yield and yield components were favored at eCO2 when N application scheduled from ET to FS of rice. Interestingly, the N application up to FS of rice showed significant improved grain fertility and reduced sterility under rising CO2. However, rice plant accumulated and translocated more nutrients from shoot to grain under elevated CO2 (eCO2) condition. Moreover, higher grain amylose and lower protein was obvious at eCO2. Collectively, rice yield increased by 18 to 20 % under eCO2 with the application of N at FS of rice. These results indicate that to maximize rice yield under eCO2, it is crucial to supply N at FS of rice in order to increase grain fertility and reduce spikelet sterility

Arbuscular Mycorrhizal Fungi Improve Growth and Phosphate Nutrition of Acacia seyal (Delile) under Saline Conditions

Many plant species adapted to semi-arid environments are grown in the Sahelian region in northern Africa. One such species is Acacia seyal (Delile), a multipurpose leguminous tree grown in various agroecological zones, including saline soils. These challenging arid and semi-arid environments harbor a diversity of arbuscular mycorrhizal fungi (AMF) communities that can develop symbiotic associations with plants to improve their hydromineral nutrition. This study compared the effects of native AMF communities isolated from semi-arid sites (high, moderate, and low salinity zones Ndiafate, Ngane, and Bambey, respectively) and the AMF Rhizoglomus aggregatum on the development and phosphate nutrition of A. seyal seedlings subject to three salinity treatments (0, 340, and 680 mM). Plant height, dry matter weight of the shoots and roots, and phosphorus uptake from the soil were measured. Plants inoculated with AMF native species from each site that were provided with up to 340 mM of NaCl had greater shoot height than plants grown under 680 mM salinity. At NaCl concentrations above 340 mM, shoot and root development of A. seyal seedlings diminished. However, dry matter production of shoots (7%) and roots (15%) improved following AMF inoculation compared with the control (respectively 0.020 and 0.07 g for shoots and roots). When inoculated with AMF isolates from the high salinity zone (Ndiafate), phosphate content/nutrition was increased by 10% around 30 days after inoculation compared with non-inoculated seedlings (2.84 mg/kg of substrate). These results demonstrate that native AMF inoculants are capable of helping plants withstand environmental constraints, especially those exposing plants to harsh climatic conditions. We discuss insights on how AMF influences the interplay between soil phosphorus and perceived salinity that may have implications for broader relationships between plants and symbiotic fungi.

Selected Indices to Identify Water-Stress-Tolerant Tropical Forage Grasses.

Periods of soil water stress have been recurrent in the Cerrado region and have become a growing concern for Brazilian tropical pasture areas. Thus, the search for forage grasses more tolerant to water stress has intensified recently in order to promote more sustainable livestock. In a greenhouse experiment, the degree of water stress tolerance of nine tropical forage grass cultivars was studied under different soil water regimes. The investigation followed a 9 × 3 factorial design in four randomized blocks. Nine cultivars from five species of perennial forage grasses were tested: Urochloa brizantha (‘BRS Piatã’, ‘Marandu’, and ‘Xaraés’), Panicum maximum (‘Aruana’, ‘Mombaça’, and ‘Tanzânia’), Pennisetum glaucum (‘ADR 300’), Urochloa ruziziensis (‘Comum’), and Paspalum atratum (‘Pojuca’). These cultivars were grown in pots under three soil water regimes (high soil water regime—HSW (non-stressful condition), middle soil water regime—MSW (moderate water stress), and low soil water regime—LSW (severe water stress)). Plants were exposed to soil water stress for 25 days during the tillering and stalk elongation phases. Twelve tolerance indices, including tolerance index (TOL), mean production (MP), yield stability index (YSI), drought resistance index (DI), stress tolerance index (STI), geometric mean production (GMP), yield index (YI), modified stress tolerance (k1STI and k2STI), stress susceptibility percentage index (SSPI), abiotic tolerance index (ATI), and harmonic mean (HM), were calculated based on shoot biomass production under non-stressful (YP) and stressful (YS) conditions. Soil water stress decreased leaf area, plant height, tillering capacity, root volume, and shoot and root dry matter production in most cultivars, with varying degrees of reduction among tropical forage grasses. Based on shoot biomass production under controlled greenhouse conditions, the most water-stress-tolerant cultivars were P. maximum cv. Mombaça and cv. Tanzânia under the MSW regime and P. maximum cv. Aruana and cv. Mombaça under the LSW regime. P. maximum cv. Mombaça has greater adaptability and stability of shoot biomass production when grown under greenhouse conditions and subjected to soil water stress. Therefore, this forage grass should be tested under field conditions to confirm its forage production potential for cultivation in tropical regions with the occurrence of water stress. The MP, DI, STI, GMP, YI, k2STI, and HM tolerance indices were the most suitable for identifying forage grass cultivars with greater water stress tolerance and a high potential for shoot biomass production under LSW regime.

Effects of seed orientation and sowing depths on germination and seedling vigour in Mahua (Madhuca longifolia)

Effects of seed orientation and depth at the time of sowing on germination and seedling vigour of Madhuca longifolia (J.Konig.) J.F.Macbr. were investigated. Seeds with uniform size were sown in sand filled earthen pots at 1.5, 3.0 and 5.0 cm depths, adopting three orientations of the embryo, viz., upright (embryo facing up), horizontal and inverted positions. The experiment was laid out in a completely randomized block design. Percentage germination, days taken for initial emergence, speed of germination, germination index, root and shoot length and dry matter production, vigour index I and vigour index II were calculated. Placing the seeds with the embryo in upright position at a depth of 1.5 cm and 3.0 cm resulted in early and higher germination, higher seedling growth, greater dry matter production and vigour index I and vigour index II.

Effect of Phosphate Organomineral Fertilization on the Dry Matter Production and Phosphorus Accumulation of Corn

Brazilian soils are typically highly weathered, naturally poor in P, and rich in minerals with high P-adsorbing capacity. The objective of the present study was to evaluate the efficiency of peat-based granulated organomineral phosphate fertilizer (OMF) on the phosphorus supply capacity, shoot dry matter production and P accumulation of corn plants, as well as its residual effect on soil, compared to that of monoammonium phosphate (MAP). The experimental was performed using a randomized block design with a 2 &amp;times; 5 + 1 factorial scheme (two fertilizer: OMF and MAP; five P doses: 15, 30, 45, 60, and 75 mg P2O5 dm-3, and one control treatments (no P fertilizer), and three replicates. Two soils (Ferralsol and Planosol) were used in this study. Soil samples were incubated with limestone for 30 days and then dried, sieved and used to fill plastic pots (3 dm3 soil per pot). Four successive corn cultivations were evaluated and, at the end of each cultivation period, the shoot dry mass (SDM) and P content of the corn were determined. In addition, soil P was measured at the end of the experiment. OMF and MAP had similar effects on SDM, but MAP provided higher P accumulation (SPA) of the first two cultivations, while OMF had higher soil residual P in Ferralsol. However, considering the total accumulated in four crops, SDM and SPA were statistically similar between the two P sources. SDM and SPA in Ferralsol increased linearly with increasing doses, while in Planosol, SPA increased linearly with increasing P dose, regardless of the P source, but SDM was not affected by increasing P doses. According to the results, OMF composed of chemically activated peat and MAP can replace MAP as phosphate fertilizer and maintain the same agronomic efficiency.

Chemical speciation of copper and manganese in solution of a copper-contaminated soil and young grapevine growth with amendment application

Copper (Cu)-based fungicide application to control foliar diseases in grapevine (Vitis vinifera L.) can increase soil Cu availability. Brazilian soils have high natural Cu and manganese (Mn) concentrations, increasing the potential for toxicity to grapevine plants. Application of amendment substances can reduce the concentrations of toxic chemical species of Cu and Mn in soil solution, especially for the soils grown with young plants. We evaluated the chemical speciation of Cu and Mn in soil solution and young grapevine growth using a contaminated soil with amendment application. Grapevine seedlings of Paulsen 1103 rootstock were grown for 12 months on an old vineyard (> 30 years of cultivation) soil without (control) and with vermicompost or limestone application. Grapevine dry matter, root morphological characteristics, and plant tissue Cu and Mn concentrations were evaluated. The cation and anion concentrations, dissolved organic carbon, pH, and chemical speciation of Cu and Mn in soil solution from different soil layers were analyzed. Vermicompost application did not reduce Cu and Mn phytotoxicity, and grapevine plants died after winter pruning. High soluble Mn concentration in soil (5.56 mg L–1 in 0–45 cm soil layer) and Mn concentration in plant tissue at pruning (380.8 mg kg–1) might be the primary cause of plant death. Limestone application reduced Cu2+ and Mn2+ chemical species in soil solution, thereby increasing plant growth. The Cu2+ and Mn2+ species were negatively correlated (P < 0.05) with grapevine shoot production at pruning (r = –0.92 and –0.97, respectively) and at the end of the trial (r = –0.73 and –0.51, respectively). Limestone application increased grapevine shoot and root dry matter production by 36% and 41%, respectively, while also presenting the highest root length and volume in the 5–10 cm soil layer. Limestone application is a viable and profitable alternative for reducing soil Cu and Mn availability and their phytotoxic effects.

Silicon mitigates nutritional stress of nitrogen, phosphorus, and calcium deficiency in two forages plants

Forages are one of the most cultivated crops in the world. However, nutritional deficiency is common, specifically in N, P, and Ca in many forage-growing regions. Silicon (Si) can attenuate the stress caused by nutritional deficiency, but studies on Si supply’s effects on forage plants are still scarce. This research was carried out to evaluate whether the Si supply can mitigate the effects of N, P, and Ca deficiencies of two forages and the physiological and nutritional mechanisms involved. Two experiments were carried out with two forage species (Urochloa brizantha cv. Marandu and Megathyrsus maximum cv. Massai). We used nutrient solution under balanced nutrition conditions and nutritional stress due to the lack of N, P, and Ca combined with the −Si and +Si. The deficiencies of N, P, and Ca in both forages’ cultivation caused damage to physiological and nutritional variables, decreasing the plant dry matter. However, in both forage species, the Si addition to the nutrient solution decreased the extravasation of cellular electrolytes and increased the content of phenolic compounds, the green colour index, the quantum efficiency of photosystem II, the efficiencies of use of N, P and Ca and the production of shoot dry matter. The beneficial effects of Si were evidenced in stressed and non-stressed plants. The research emphasised the advantage of using Si to grow U. brizantha and M. maximum under N, P, and Ca deficiency, contributing to their sustainable cultivation.