NGHIÊN CỨU KHẢ NĂNG SINH TRƯỞNG PHÁT TRIỂN, NĂNG SUẤT VÀ CHẤT LƯỢNG CỦA MỘT SỐ GIỐNG DƯA CHUỘT TẠI TỈNH THỪA THIÊN HUẾ

Nghiên cứu được tiến hành trên 7 giống dưa chuột gồm Champ 937, F1 Phú Nông 779, Kiếm Đài Loan, Madam 579, CUS 067, CUS 070 và giống đối chứng Chaiyo 578. Thí nghiệm thực hiện ngoài đồng ruộng trong vụ Xuân Hè năm 2020 tại tỉnh Thừa Thiên Huế nhằm mục đích đánh giá đặc điểm sinh trưởng, phát triển, năng suất, chất lượng của các giống dưa chuột và xác định được giống dưa chuột phù hợp với điều kiện sinh thái. Kết quả nghiên cứu cho thấy các giống thí nghiệm có thời gian sinh trưởng ngắn ngày (65 - 80 ngày), phù hợp với điều kiện địa phương. Các giống dưa chuột có năng suất thực thu cao hơn so với giống đối chứng (19,87 tấn/ha) như Kiếm Đài Loan (29,93 tấn/ha), CUS 067 (22,26 tấn/ha), F1 Phú Nông 779 (22,60 tấn/ha) và có chất lượng tốt như ruột quả đặc, quả giòn, không bị đắng ở đầu quả, vỏ quả màu xanh đến xanh đậm phù hợp với thị hiếu người tiêu dùng. ABSTRACT The study was conducted on seven cucumber varieties including Champ 937, F1 Phu Nong 779, Kiem Taiwan, Madam 579, CUS 067, CUS 070 and Chaiyo 578 as a control. The field experiment was carried out in Spring-Summer crop season of the year 2020 in Thua Thien Hue province to evaluate the growth, development, yield, and quality of these cucumber varieties and to identify the cucumber varieties which are suitable for ecological conditions in Thua Thien Hue province. The results showed that these varieties were a short growing time (from 65 days to 80 days), suitable for local conditions. Kiem Taiwan, CUS 067 and F1 Phu Nong 779 varieties had higher fruit yield, 29.93, 22.26 and 22.60 ton/ha, respectively and better qualities than the control sụch as the inside of cucumber was thick and crunchy, the top of the cucumbers was not bitter, the peels were from green to dark green which were suitable for the tastes of consumers.

N2O Emissions From Residues of Oat and Grass Pea Cover Crops Cultivated in the US Southern Great Plains

Grass pea (Lathyrus sphaericus) and oat (Avena sativa) are potential cover crops for spring periods of summer crop systems in the US Southern Great Plains (SGP). The main objective of this study was to compare nitrous oxide (N2O) emissions from residues of grass pea and oat grown as green nitrogen (N) crops. The comparisons included responses from plots cultivated with oat, grass pea, and control (spring-fallowed) plots. Two management options were applied to grass pea: residues retained and aboveground biomass removed for forage. Crabgrass (Digitaria sanguinalis) was cultivated as a main summer crop immediately after termination of the cover crops. Fluxes of N2O were measured by closed chamber connected to a portable gas analyzer on 23 dates during a 3 month growing period for crabgrass. At termination, oat produced more aboveground biomass than grass pea (2.17 vs. 3.56 Mg ha−1), but total N in biomass was similar (102–104 kg ha−1) due to greater N concentrations in grass pea than oat (4.80% vs. 2.86% of dry mass). Three month cumulative emissions of N2O from grass pea-incorporated plots (0.76 ± 0.11 kg N2O-N ha−1; mean ± standard error, n = 3) were significantly lower than from oat-incorporated plots (1.26 ± 0.14 kg N2O-N ha−1). Emissions from grass pea plots with harvested biomass (0.48 ± 0.04 kg N2O-N ha−1) were significantly lower than those from grass pea-incorporated plots. Cumulative N2O emissions from control plots were significantly greater than those from grass pea-harvested plots but were similar to the emissions from grass pea-incorporated plots. Yields produced by crabgrass were similar from all cover crop treatments (8.65–10.46 Mg ha−1), but yield responses to the control (18.53 Mg ha−1) were significantly larger. Nitrogen concentrations in crabgrass were greater in response to oat- and grass pea-incorporated plots (2.86–2.87%) than in grass pea-harvested (1.93%) and control (1.44%) plots. In conclusion, the results indicated that (i) post-incorporation emissions of N2O can be greater from a non-legume green N crop than a legume green N crop due to greater biomass productivity of the cereal, and (ii) emissions of N2O could be mitigated by removing biomass of the green N crop for use as forage.

Sowing date and maturity groups on the economic feasibility of soybean-maize double summer crop system

The success of soybean-maize double summer crop is very dependent on the sowing date and relative maturity group of cultivars. This study aimed to evaluate the economic feasibility of the adoption of soybean-maize double cropping under different sowing periods and soybean maturity groups. The production data used were obtained from two summer growing seasons (2016/17 and 2017/18) in an experiment carried out at Dois Vizinhos-PR, Brazil. The economic feasibility of each treatment was evaluated through the indicators of gross revenue, gross margin, operating profit, and profitability index. Soybean-maize succession is viable and presents positive profitability. Soybean establishment on October 15th makes it economically unfeasible to sow maize (outside the zoning) as a 2nd summer crop. Soybean maturity groups from 5.1 to 5.3, when sown on October 1st allow profitability and better financial balance, being this combination the most suitable for a double summer crop. Soybean genotypes with maturity group 6.0 are an option for sowing in the middle of September, being the most lucrative and efficient arrangement, providing maize sowing in the middle of February, within the agroclimatic zoning of the region.

Does the residual effect of n-fertilization applied on corn phase maintain forage production of the following pasture phase in an integrated crop-livestock system?

Nutrient cycling represents an important nutrient source in the Integrated Crop-Livestock Systems (ICLS). In general, only the crop phase of the ICLS is fertilized, however little is known about this residual effect of nitrogen fertilization from summer crop to succeeding winter pasture. This research aimed to evaluate the forage growth dynamic and botanical composition of a mixed pasture of black oat (Avena strigosa Schreb) and ryegrass (Lolium multiflorum Lam.) affected by two canopy height managements (high and low) and nitrogen fertilization applied to either the summer crop (corn) or winter pasture phase of an ICLS. The experiment was established in 2012 in southern Brazil. Black oat and ryegrass were growing during winter season and corn (Zea mays L.) during summer season, being this paper related to the 2014 pasture period. Treatments were composed by two canopy heights (25 and 10 cm) and two N-Fertilization Times (N-Pasture or N-Corn) of 200 kg of N ha-1. Canopy height was regulated by beef steers grazing through continuous stocking with a variable stocking rate. Forage mass was lower in the 10 cm canopy height on average, however this forage mass was composed by greater proportion of ryegrass leaves and lower proportion of dead material in relation to the treatment with 25 cm canopy height. The N-fertilization applied directly on pasture phase (N-Pasture) increased forage mass, tiller population density, participation of ryegrass and ryegrass leaf proportion in the forage mass. Furthermore, when pasture was fertilized with N, the forage accumulation rate increased about 69%, highlighting that the corn N-fertilization did not present significant effect on forage productivity. The residual effect of corn N-fertilization was not enough to maintain high forage accumulation. Thus, the pasture N-fertilization is fundamental to keep high-productive crop-livestock system.

Fungicides application in corn disease control and mycotoxin accumulation in grain

In Brazil, corn planted area increased by 30%. Therefore, there was also an increase in the incidence of pathogens in the crop. The objective of this work was to evaluate the influence of fungicide applications on corn crops in the different growth stages for the control of the diseases and its effect on the occurrence of mycotoxins in the grain. The experiment was carried out in the 2017/2018 summer crop, in the municipality of Cruz Alta, state of Rio Grande do Sul/BR. This study used P 1630 hybrid, in a randomized block design with eight treatments (control, V8, PT, V4 + V8, V4 + V8 + PT, V8 + PT, V8 + PT + 15, PT + 15) and three replicates. The fungicide fluxapiroxade + pyraclostrobin + epoxiconazole at the dose of 1.0 L/ha-1 was used. The diseases that affected the crop were the white spot and helmintosporiosis, therefore, reducing the incidence of diseases. Also the highest yields were obtained where the applications started at the phenological stage V4 and V8. The levels of mycotoxins detected in this work remained within the limits of the legislation, with a significant reduction in the accumulation of fumonisin and aflatoxin with fungicide applications.

Profitability of maize for silage fertigated with nitrogen doses in different crops in a semiarid region of Brazil

The objective of this work was to determine the adequate nitrogen (N) dose via fertigation associated with the maximum economic production of maize for silage, in two agricultural crops (summer and winter), in the municipality of Canindé de São Francisco-SE, Brazil. The experimental design was in randomized blocks, with four replicates. The treatments consisted of four doses of N (0, 80, 160, and 240 kg ha-1) using urea. The cultivar planted was the hybrid Bt Feroz. The evaluated characteristics were as follows: shoot fresh and dry mass productivity, gross and net incomes, the rate of return and net profit margin. There was an interaction between N doses and agricultural crops for all variables. Higher agroeconomic efficiency in the production of maize for silage was obtained from the winter harvest. In the summer crop, the rate of return (1.82) and the net profit margin (45.52%) were highest when the plants were fertigated with 56.04 and 58.92 kg ha-1 of N, respectively. In winter, the yields of fresh mass, gross and net incomes increased linearly with increasing doses of N, with a profit proportional to the invested capital since nitrogen fertigation did not influence the rate of return (2.24) and the net profit margin (55.22%).

Pruning and dormancy breaking make two sustainable grape-cropping productions in a protected environment possible without overlap in a single year

In table grape production, protected cultivation in a vineyard in different regions and climates is currently a commonly used practice. The aims of this study were to provide key approaches to sustainably produce two crops of grape without overlap under protected environment in a single year. Spraying the degreening chemicals 400 mg/L ethephon +0.4% sulfur at 4 weeks of vine nutrient restoration after the harvest of the summer crop resulted in the highest percentage of sprouting inflorescence. The retention of 7–10 buds in the base shoot results in the high percentage of sprouting inflorescence. Bud breaking chemicals with 2.5% hydrogen cyanamide+2.0% Baoguoliang +0.02% Shenzhonggen significantly led to sprout inflorescence more efficiently. Cluster and fruit weights of the winter crop weighed significantly less than those of the summer crop. However, the contents of total soluble sugar and titratable acidity were higher than those of the summer crop. The anthocyanin content in the peel of the winter fruit was significantly higher than that in the summer fruit. The yield of the winter crop is controlled by the yield of the summer fruit. To maintain the stability of the two crops for one year, the ratio of yield in the winter to the summer should be controlled from 2:5 to 3:5 to ensure the sustainable production of two crops without overlap for ‘Summer Black’ grape. These results may help grape growers to overcome the impacts of rainy and hot climates with the help of protected facilities, and it could enable the use of solar radiation and heat resources in subtropical and tropical areas.