Impacts of the nitrogen application on productivity and nutrients concentrations of the corn-Congo grass intercropping system in the dry season

ABSTRACT

The corn-grass intercropping system began to be used in the dry season, as it provides increased straw production for the no-tillage system. However, corn and grass are plants demanding in nitrogen. The corn cultivated in the dry season is called out-of-season corn in Brazil. The objective of this study was to evaluate the productivity and nutrients concentrations of out-of-season corn and Congo-grass intercropped in the no-tillage system, as a function of the nitrogen rates applied in sidedressing. The treatments were four nitrogen rates, 0, 30, 60 and 90?kg?ha^?1. The experimental design was randomised complete blocks with four replicates. The experimental period corresponded to the harvests of 2015 and 2016. There were evaluated: corn grain yield, dry mass production and nutrient concentration in the shoots of the plants intercropped. The evaluations were carried out at the physiological maturity stage of the corn and at the time of desiccation of the grass. Nitrogen increased grain yield and dry mass production of the plants intercropped. Nitrogen maximised the magnesium concentration in out-of-season corn and the nitrogen, calcium, magnesium and sulphur concentrations in Congo grass. Excess nitrogen promoted reduction of the phosphorus in the Corn-Congo grass intercropping system in the dry season.     

Nitrogen transfer from green manure to organic cherry tomato in a greenhouse intercropping system

Abstract

This work aimed to evaluate the nitrogen transfer, the yield and the nutrient contents of organic cherry tomatoes intercropped with legumes in two successive years. The randomized block experimental design was used with eight treatments and five replicates, as follows: two controls with single cherry tomato crop (with and without corn straw cover); cherry tomato intercropped with jack bean (Canavalia ensiformis DC); white lupine (Lupinus albus L.); sunn hemp (Crotalaria juncea L.); velvet bean-dwarf [(Mucuna deeringiana (Bort) Merrill)]; mung bean (Vigna radiata (L.) Wilczek), and cowpea (Vigna unguiculata (L.) Walp). The number of total fruits, the weight of total fruit and an average weight of the total fruit in the first year was 25%, 33% and 13% higher than the second-year, respectively. The lower N-content of cherry tomato leaves in the treatment with mung bean can be reflected of lower %N transfer of cherry tomato leaves in the same treatment compared to treatment with cowpea bean. The N-content and %N transfer of cherry tomato leaves was 50 and 42% higher in year 1 than in year 2, successively. Nevertheless, in general, the legumes used in this study contributed equally in the N transfer to the cherry tomato plants. The P, K, Mg, Ca, Cu, Mn, Fe and Zn content in the leaf and shoot were no difference between the treatments. However, the Mg, Ca, Cu, Fe, Mn and Zn content of the leaf were higher in year 2 than year 1.     

Performance and nematode infection of ewe lambs on intensive rotational grazing with two different cultivars of <Emphasis Type="Italic">Panicum maximum</Emphasis>

The daily live weight gain (DLWG), faecal nematode egg counts (FEC), and packed cell volume (PCV) of Suffolk, Ile de France and Santa Inês ewe lambs were evaluated fortnightly for 56 days in the dry season (winter) and 64 days in the rainy season (summer) of 2001-2002. The animals were distributed in two similar groups, one located on Aruana and the other on Tanzania grass (Panicum maximum), in rotational grazing system at the Instituto de Zootecnia, in Nova Odessa city (SP), Brazil. In the dry season, 24 one-year-old ewe lambs were used, eight of each breed, and there was no difference (p > 0.05) between grasses for DLWG (100 g/day), although the Suffolk had higher values (p < 0.05) than the other breeds. In the rainy season, with 33 six-month-old ewe lambs, nine Suffolk, eight Ile de France and 16 Santa Inês, the DLWG was not affected by breed, but it was twice as great (71 g/day, p < 0.05) on Aruana as on Tanzania grass (30 g/day). The Santa Inês ewe lambs had the lowest FEC (p < 0.05) and the highest PCV (p < 0.05), confirming their higher resistance to Haemonchus contortus, the prevalent nematode in the rainy season. It was concluded that the best performance of ewe lambs on Aruana pastures in the rainy season is probably explained by their lower nematode infection owing to the better protein content of this grass (mean contents 11.2% crude protein in Aruana grass and 8.7% in Tanzania grass, p < 0.05) which may have improved the immunological system with the consequence that the highest PCV (p < 0.05) observed in those animals.     

Pore water geochemistry and diagenesis of estuary sediments—an example of the Zrmanja River estuary (Adriatic coast,Croatia)

Journal of Soils and Sediments - The geochemistry of pore waters from sediments deposited in the semi-enclosed bay of the Zrmanja River estuary, encompassing two small interconnected basins, the...     

Morphological and molecular characterization of <Emphasis Type="Italic">Diaporthe (</Emphasis>anamorph <Emphasis Type="Italic">Phomopsis)</Emphasis> complex and pathogenicity of <Emphasis Type="Italic">Diaporthe aspalathi</Emphasis> isolates causing stem canker in soybean

The complex of Diaporthe (asexual morph) species occurring on soybean constitutes an important pathogenic group associated with diseases such as pod and stem blight, seed decay and stem canker. Stem canker, caused by Diaporthe aspalathi, has been reported as the most aggressive form of canker and its occurrence has limited soybean crop productivity in the southern United States. The main form of pathogen control is the use of stem canker resistant soybean varieties. In this study, strains of Diaporthe and Phomopsis were isolated from stem and seeds of soybean in different locations in South America during the years 1989–2014. Genomic DNA from 26 isolates were analyzed by PCR-restriction fragment length polymorphism (RFLP) and Amplified Fragment Length Polymorphism (AFLP) techniques, and sequencing of internal transcribed spacer (ITS) regions of ribosomal DNA. The molecular analysis of ITS sequences by alignment with those of ex-type strains deposited in GenBank and morphological characteristics allowed the identification of Phomopsis longicolla, D. phaseolorum var. sojae, D. caulivora and D. aspalathi. An analysis of the pathogenicity of 13 isolates of D. aspalathi inoculated in soybean genotypes carrying different resistance genes to stem canker (Rdm1, Rdm2, Rdm3, Rdm4, Rdm5 and Rdm?) enabled us to identify the occurrence of at least three races of D. aspalathi occurring in Brazil. Among the isolates identified as D. aspalathi, both molecular and phenotypic analyses showed clustering depending on the date of collection and pathogenicity, which revealed the existence of variability of the pathogen.     

Hydroxycinnamic acid amide derivatives, phenolic compounds and antioxidant activities of extracts of pollen samples from Southeast Brazil

Seven bee pollen samples (C1-C7) with different palynological sources were harvested from Pindamonhangaba municipality (Southeast Brazil). Methanol extracts of untreated samples (control), samples frozen at -18 °C and samples frozen and then dried were analyzed by HPLC/PAD/ESI/MS/MS. Flavonoid diglycosides of quercetin, kaempferol, isorhamnetin and patuletin were detected, together with hydroxycinnamic acid amide derivatives, such as N',N',N'-tris-p-feruloylspermidine and N',N',N'-tris-p-coumaroylspermidine. Distinct phenolic profiles characterized the analyzed samples, but no differences were noted as resulting from different treatments. Total phenolic contents determined with the Folin-Ciocalteau reagent ranged from 1.7 to 2.2%. Antioxidant activities above 75%, based on the DPPH method, were observed for all extracts, not correlated with total phenolic contents. Among samples from the same origin, those frozen were more active than samples untreated (control), and the samples frozen and then dried were the most active.     

The influence of phosphorus and calcium application rates on the mineral composition of the perennial legume Macrotyloma axillare

The response of legumes to the supply of either phosphorus (P) or calcium (Ca) alone has been extensively investigated but no prior studies have evaluated their combinations in the perennial legume Macrotyloma axillare (Macrotyloma legume). This study assessed the mineral composition of Macrotyloma legume in response to the combined application of P and Ca in an Ultisol. The experiment was conducted in a greenhouse in Nova Odessa city, São Paulo, Brazil. Five rates of P and Ca, respectively, were combined in a 5² incomplete fractional factorial design. Thus, the treatments consisted of 13 P and Ca combination rates (respectively, in mg dm^?3): 0?0, 0?40, 0?80, 15?20, 15?60, 30?0, 30?40, 30?80, 45?20, 45?60, 60?0, 60?40 and 60?80 arranged in a randomised block design with four replications. Mineral composition was evaluated after two harvests (53 d after sowing and 34 d after the first harvest). During the initial growth of the Macrotyloma legume, P × Ca interactions occurred. The P supply antagonistically influenced the nitrogen content. The excess P supply reduced nitrogen accumulation in the shoots and caused a lack of nitrogen in the leaves. The Ca supply synergistically impacted the magnesium content and caused a ‘Viets effect’ in potassium content.     

Mycoflora and occurrence of alternariol and alternariol monomethyl ether in Brazilian sunflower from sowing to harvest

The present study aimed to analyze the mycoflora and the occurrence of alternariol (AOH) and alternariol monomethyl ether (AME) in grain samples of sunflower during different stages of plant development in Nova Odessa, State of S?o Paulo, Brazil. The data obtained were correlated with the presence of fungi in soil, wind-dispersed fungi, and the predominant climatic conditions of the region where the experiment was carried out. Analysis of the mycoflora revealed the presence of Fusarium verticillioides and Alternaria alternata in 70% and 46% of the samples, respectively. The profile of wind-dispersed fungi also showed F. verticillioides as the most frequently isolated fungus (68%), although A. alternata was detected in 28% of samples. In soil, Penicillium was the most frequent species (49.9%), followed by F. verticillioides (47.7%) and A. alternata (10.9%). Regarding water activity, sunflower grains presenting a high frequency of isolation of F. verticillioides and A. alternatahad a water activity ranging from 0.92 to 0.96, and statistical analysis revealed a negative linear correlation between the isolation of fungi and water activity. HPLC analysis showed that 18% of the sunflower grains were contaminated with alternariol (24.9-170.9 ng/g) and 10% with alternariol monomethyl ether (14.1-108.6 ng/g). The contamination of sunflower grains with AOH and AME in the field was low when compared to the LD50 necessary to cause toxicity to animals. However, the contamination with other toxigenic fungi such as F. verticillioides may indicate the presence of other mycotoxins in sunflower grains and a possible synergistic effect between them. This is the first report of the natural occurrence of alternariol and alternariol monomethyl ether in sunflower grains in Brazil.