Effect of thermosonication on enzymatic oxidation and physicochemical properties of soursop (Annona muricata) pulp

Soursop is an exotic tropical fruit, highly perishable, presents losses around 30% in postharvest, has marked commercial importance especially for internal consumption and a maximum shelf life. The objective of the present work was to study the effect of thermosonication (TS) on some physicochemical properties and the enzymatic oxidation of soursop pulp. The thermosonication treatments used on the samples were at 40 kHz, in a temperature range between 20-60 ºC, for 25 minutes. The soluble solids, pH, vitamin C concentration, inactivation of peroxidase (POD) and polyphenoloxidase (PPO) in the soursop pulp were evaluated before and after the treatments. The results indicate a loss of vitamin C was observed in a 2.63; 13.16 and 28.95% for temperatures at 20, 40 and 60 ºC, respectively. On the other hand, a partial inactivation of the enzymes, POD, in 48.41; 69.83 and 74.24% and for PPO in 56.38; 74.47 and 81.91% was achieved at temperatures at 20, 40 and 60 ºC respectively. Finally, it was demonstrated that the US combined with heat (TS) inactivates in a large percentage the POD and PPO enzymes in the soursop pulp needing less heat, which could make it more efficient in comparison with the thermal treatments. Highlights Ultrasound combined with heat (TS) can inactivate POD and PPO enzymes in the soursop pulp, achieving considerable retention of vitamin C. Peroxidase (POD) and Polyphenoloxidase (PPO) trigger enzymatic processes affecting product natural color. Soursop is an exotic fruit with high levels of bioactive compounds, and great agro-industrial potential given its high recovery yields and excellent sensory characteristics. A vitamin C retention level of 71.05- to 86.84% was achieved in soursop pulps that have undergone thermosonification.

Does foliar nicotinamide application affect second crop corn (Zea mays)?

The largest corn yeld in Brazil is currently in the second harvest, which is the most susceptible period to climatic adversities occurring during the cycle. Thus, introducing beneficial elements for maintaining the adequate development of the plant can help producers in obtaining greater kernel yields. Among studied elements, nicotinamide has potential use since it is associated with accumulating secondary metabolites and manifesting defence metabolism in plants. The objective of this work was to evaluate the influence of nicotinamide applied in different doses (only once or in instalments) on the biometric and productive characteristics of corn. The treatments were composed by the number of nicotinamide applications (one or two) and five doses (0, 50, 100, 150 and 200 mg L-1). Plant diameter, plant height, ear insertion height, leaf area and dry matter, yield and 100-kernel mass were evaluated. It was found that doses close to 100 mg L-1 resulted in increases in vegetative and reproductive development, regardless of the number of applications. In this way, foliar nicotinamide application positively influences the biometric and productive characteristics of second crop corn. Highlights The use of nicotinamide in corn plants improves its growth, yield components and grain yield. A single application of nicotinamide during vegetative stage V3 at a dose of 100 mg L-1 is sufficient to increase the leaf area of corn plants. Corn grain yield can be increased by 12.6% with a single application of nicotinamide. There was no need for two applications of nicotinamide in corn crop.

Competitive ability of canola (Brassica napus var. oleifera) hybrids with black oat (Avena strigosa) in a subtropical environment

The objective of this study was to assess the competitive ability of canola (Brassicanapus var. oleifera) hybrids in competition with black oat (Avena strigosa) in a subtropical environment. The experiments were conducted in a greenhouse where canola hybrids ‘Hyola 61,’ ‘Hyola 76,’ ‘Hyola 433,’ and ‘Hyola 571’ were tested individually for their competitive performance with black oat. The plant proportion between black oat and the canola hybrid was changed (100%:0%; 75%:25%; 50%:50%; 25%:75%; and 0%:100%) while keeping the total population of plants constant (20 plants plot‑1). Photosynthesis rate (μmol m-2 s-1), internal CO2 concentration (μmol mol-1), and transpiration rate (mol H2O m-2 s-1) were assessed using an infrared gas analyzer 55 days after emergence. Leaf area (m2 m-2) and dry matter (g m-2) were also assessed on the same day. The data set was analyzed by the replacement series method for competition studies. There was evidence of intense competition between canola and black oat, independent of plant proportion. The competitive ability of canola was distinct among hybrids; Hyola 571 performed better than the others in the competition against black oat. Choosing the most competitive hybrid, such as Hyola 571, helps maintain high canola grain yield levels in areas infested with black oat. Highlights: There is difference in competition among canola hybrids against black oat; Hyola 571 performed better in the competition; Preference should be given for most competitive canola genotypes against weeds, and weed control should be carried out early in the critical period of interference; Aggressiveness is the most preponderant parameter in determining canola genotypes with superior ability in competition against weeds.

Mycorrhizal fungi and phosphate fertilization in the production of Euterpe edulis seedlings

The present study evaluated the effect of arbuscular mycorrhizal fungi (AMF) inoculation on growth and nutrition of Euterpe edulis seedlings, supplemented or not with phosphate fertilization. The experiment was conducted in a greenhouse. The randomized block design, consisted of a 3x2 factorial arrangement and 4 replicates, with two phosphorus doses (0 and 50 mg dm-3 of soil), two microbiological treatments (Rhizophagus clarus; laroideoglomus etunicatum; R. clarus + C. etunicatum) and control (without fungus). Sowing and inoculation occurred concurrently in 2 kg plastic bags. Height, collar diameter, leaf area, dry shoot mass, macronutrient content and mycorrhizal colonization percentage were determined after 226 days. Regarding mycorrhizal colonization percentage, R. clarus resulted significantly beneficial for the production of E. edulis seedlings. In the absence of phosphate fertilization, R. clarus and mixed inoculum increased all biometric variables and macronutrient contents in seedlings. Therefore, it is concluded that AMF inoculations provide beneficial effects for growth and nutrition of E. edulis seedlings, resulting in more vigorous plants at a low-cost strategy. Highlights: Rhizophagus clarus resulted significantly beneficial for the production of E. edulis seedlings and in the absence of phosphate fertilization, and mixed inoculum ( clarus + Claroideoglomus etunicatum) increased all biometric variables and macronutrient contents in seedlings. The AMF inoculations provide beneficial effects for growth and nutrition of E. edulis seedlings, resulting in more vigorous plants at a low-cost strategy. The AMF, a biological agent of mutualistic associations with plants, constitutes an innovative approach to sustainable agriculture, contributing to increase plant survival rate, a key-factor for the successful reintroduction and conservation of E. edulis, as well as for its commercial exploitation.

Root length density (RLD) of oil palm (Elaeis guineensis Jacq) in a haplic Luvisol in Chiapas, Mexico

The tight relationship between root architecture and uptake capacity of soil water and minerals, is well established. Support roots, generally long-lived, perform support functions such as transportation and food storage. Absorbing roots, thin and short-lived, absorb nutrients and regulate plant metabolism. Roots distribution in the soil profile is crucial for plant development. It optimizes resource usage and ensures a prompt response to seasonal changes. This work aimed to study the vertical distribution of the root system of nine-year-old oil palms in a haplic Luvisol, low fertility, moderately acidic, with Nitrogen (N) and Potassium (K) deficiency, average content of Phosphorous (P), and medium to low Cation Exchange Capacity (CEC). Using the cylinder method, soil samples were collected every 10 cm and down to 150 cm of soil depth, from each cardinal side of three soil profiles. The results showed that oil palms had good root development. Most roots (73%) were found in the first 30 cm of soil, with a predominance of fine roots (78%). At 50 cm in depth, fine roots represented 88%, thin roots, 67% and medium roots, 94%. Further study should assess root length density at 15, 20, 25, and 30 years. Highlights - Haplic luvisols are optimal soils for oil palm cultivation due to their depth (> 150cm), over 50% base saturation, and pH of 5.5-6.6. - Root length density (RLD) decreased as soil depth increased. Although most oil palm roots are found in surface horizons, roots can still be found at depths of up to 1.5-5 m. - The highest number of oil palm roots (73%) was found in the first 30 cm, with 78% of fine roots. - Fine roots were distributed throughout the entire soil profile, evidencing high nutrient-absorption and metabolic activities.

Implantation of corporate social responsibility measures in the horticulture in Mexico and Spain

This work presents the results of a survey, following the Delphi methodology, to experts from the horticultural sector of Mexico and Spain. Interactions with experts have made it possible to identify relevant aspects where the level of consensus is high about the proliferation of Corporate Social Responsibility (CSR) initiatives in the export sector of both countries, standing out: the horticultural sector's leadership in the implementation of standards, which responds to the demand for destination supermarkets in the US and Europe, which despite their particularities, have similar dynamics. Not implementing is considered a risk factor; the implementations are positive actions, which enhance the reputation of companies. Agricultural companies that have a lack of business culture, ignorance, and high administrative burden limit their development, especially among smaller production companies. The greatest progress has been made in the area of labor and environmental practices, areas where consumer concern is growing. Despite CRS initiatives are not providing an immediate benefit to companies, strategic spending is valued. The research is completed with a SWOT analysis (Weaknesses, Threats, Strengths and Opportunities), providing a valuable ranking of great interest for the design of competitive improvements. Highlights Corporate Social Responsibility (CRS) measures in the horticultural activity are driven mainly for the Supermarkets Chains. There are other factors to implement it: gain competitive advantage, improve the reputation of the sector, stay in the market. The Delphi Method is a useful instrument to identify advantages, limitations, and barriers to adopt food safety and Social Responsibility Standards in the global value chain in the agricultural sector. The horticultural activity is adopting several CRS standards in order to stay in the market such as: GRASP, FAIR TRADE, SEDEX, SA 8000. The Delphi Panel considers that the CRS standards and measures implemented improve the labor, environmental and human rights in the horticultural activity in Mexico and Spain.

Effect of plot size and plant spatial arrangement on the efficiency of family selection in sugarcane

The purpose of this study was to identify the ideal sample size representing a family in its potential, to identify superior families and, in parallel, determine in which spatial arrangement they may have a better accuracy in the selection of new varieties of sugarcane. For such purpose, five families of full-sibs were evaluated, each with 360 individuals, in the randomized blocks design, with three replications in three different spacing among plants in the row (50 cm, 75 cm, and 100 cm) and 150 cm between the rows. To determine the ideal sample size, as well as the better spacing for evaluation, the bootstrap method was adopted. It was observed that 100 cm spacings provided the best average for the stalk numbers, stalk diameter and for estimated weight of stalks in the stool. The spacing of 75 cm between the plants allowed a better power of discrimination among the families for all characters evaluated. At this 75 cm spacing was also possible to identify superior families with a sample of 30 plants each plot and 3 reps in the trial. Highlights The bootstrap method was efficient to determine the ideal sample size, as well as the best spacing for evaluation. The 75-cm spacing had the highest power of discrimination among families, indicating that this spacing is the most efficient in evaluating sugarcane families for selection purposes. From all the results and considering selective accuracy as the guiding parameter for decision making, the highest values obtained considering the number of stalks and weight of stalks in the stools were found at the 75-cm spacing.

Implementation of iceplant production under semi-controlled conditions

Mesembryanthemum crystallinum is considered a drought and saline stress-tolerant plant with many biological activities that has been revalued as cool flavouring plant. The objective of this work was to assess optimum mode of cultivation of M. crystallinum to produce edible parts under greenhouse conditions. Therefore, three soilless media were evaluated: peat, vermiculite and hydroponic culture. Pot culture in peat did not result to be a good substrate for iceplant, with little biomass production. However, vermiculite and hydroponics allowed optimum growth of M. crystallinum, with a significantly greater yield in plants grown in vermiculite irrigated with nutrient solution. In fact, plants cultivated in vermiculite enhanced leaf area and leaf fresh weight, together with high foliar concentrations of N, Mg, Mn, Fe, Na, clorophylls and carotenoids. Furthermore, increased succulence and Na concentration of edible parts of glacier lettuce grown in vermiculite can offer more interesting taste, consistence and nutrient content for consumers. Higlights Hydroponic and vermiculite cultures led to optimum crystallinum growth. Peat pot culture did not seem to be an adequate substrate to cultivate crystallinum. Ice plants grown in vermiculite presented highest leaf fresh yield and high foliar N, Mg, Mn, Fe, Na, chlorophyll and carotenoid concentrations.

Germination and development of M1 seedlings of two Selliera radicans Cav. accessions subjected to gamma radiation

Selliera radicans is a creeping plant native to Chile, New Zealand and Australia. It is increasingly used in the ornamental industry, and there is interest in breeding it to create commercial varieties. The aim of this study was to determine the effects of different doses of gamma radiation applied to the seeds on the germination and development of seedlings (M1) and the LD50 of two accessions of Selliera radicans for use in the induction of mutations. Seeds of the Vichuquén and La Serena accessions were exposed to 0, 100, 200, 300, 400, 500, 600 and 700 Gy from a 60Co source. Weekly germination percentages along with seedling numbers and lengths were recorded. Vichuquén seeds were more sensitive to this physical agent. The LD50 was 243.9 Gy for Vichuquén and 445.6 Gy for La Serena. Seedling lengths reached almost 4 mm for Vichuquén and 11.3 mm for La Serena at 12 weeks after sowing. Doses lower than 200 Gy are recommended since higher doses do not allow the development of seedlings to the extended cotyledon stage. Highlights: This is the first radiosensitivity study for the Goodeniaceae family and therefore for the Selliera genus. This study shows the specific effect of gamma radiation at the level of germination and seedling formation according to accession of origin. This study could be used for the genetic improvement of Selliera radicans via the induction of mutations.

Assessment of fodder corn grown under surface and subsurface drip irrigation in Mendoza, Argentina

Drip irrigation –surface (DI) and subsurface (SDI)– is one of the best irrigation systems to increase both irrigation and water use efficiency. The objective of this research is to assess and compare the response of fodder corn to SDI treatments at two depths with DI in Mendoza. A full factorial experimental design was used on random plots and measurements were replicated through time. Tests were run in two consecutive cycles. Germination percentage (GP), yield, water use efficiency (WUE) and water productivity (WP) were assessed. High yields ranging from 70,214 to 105,771 kg ha-1 of green matter and from 10,020 to 22,476 kg ha-1 of dry matter (DM) were obtained in both cycles, respectively. DM production from the first sowing was significantly higher in both cycles under SDI treatment than under DI. No significant differences in WP or WUE were found. GP and soil moisture (SM) did not show differences between treatments, but significant differences were found in SM (p=<0.0001) between the first soil layer and the other two layers. Highlights Germination percentage was not affected by the depth of the drip irrigation lines. No significant differences were found in green matter yields between treatments in both crop cycles. High crop water use was achieved. WUE values were 12 percent (and up to 41 percent) higher.