Agronomy Science and Biotechnology

Initial growth and chlorophyll indices of maize plants originating from seeds of different shapes and sizes

2023-09-10T19:25:01-03:00

The objective of this work was to evaluate the initial growth and chlorophyll content of maize plants originated from seeds with different sizes and shapes, as well as to establish the relationship between growth traits, chlorophyll index and seed formats. The experimental design was a randomized complete blocks, and the treatments were composed by seeds of four sizes and shapes for each of the two genotype used, and four collection periods (21, 24, 27 and 30 DAE) and four replications. The root and shoot length, stem diameter, leaf area, dry mass of leaf, stem, roots and total, leaf mass ratio, leaf area ratio, specific leaf area and chlorophyll a, b and total chlorophyll were determined. It was verified that seedlings of genotype "A" originated from large round seeds, presented the highest stem diameter, leaf dry mass, stem dry mass, root dry mass and total dry mass. There is a distinct response in the growth of maize plants as a function of the genotype. Regardless of the genotype, the size and shape of seeds do not influence the indexes of chlorophyll a, b and total. There is a positive and strong correlation between seeds of different sizes and shapes with leaf area, leaf dry mass and specific leaf area.

Artificial defoliation and its impact on the agronomic performance of sunflower in a non-preferential season

2023-11-18T15:42:50-03:00

The objective of this work was to evaluate the partitioning of photoassimilates in sunflower plants sown in a non-preferential season coincident with the occurrence of fallow areas in the region, submitted to artificial defoliation with 100% intensity, in different phenological stages of the reproductive period. The experimental design used was randomized blocks with six treatments and three replications, consisting of 18 experimental units and all plants were defoliated. The treatments performed were artificial defoliation, I: No defoliation (control); II: Defoliation at the R1 phenological stage; III: Defoliation at the R3 phenological stage; IV: Defoliation at the R5 phenological stage; V: Defoliation at the R7 phenological stage and VI: Defoliation at the R8 phenological stage. Artificial defoliation performed at 100% intensity at different phenological stages influences the morphological attributes and yield components of sunflower in a distinct way. Defoliations performed at R1 phenological stage have a negative effect on most of the variables analyzed, which provided lower plant height, stem diameter, capitulum diameter, number of rows of achenes, number of achenes per row, achene length, achene width, thousand achene mass and, consequently, in grain yield. This phenological stage was marked by the beginning of the reproductive period, which has a high demand for photoassimilates to maintain plant metabolism and yield. Defoliation performed at R8 phenological stage had better performance for plant height, capitulum diameter, capitulum mass, number of rows of achenes, number of achenes per row, number of plants per hectare and grain yield (>1000 kg ha^-1). The plants of experimental units without defoliation had results similar to those defoliated in the R8 phenological stage, however, they still had better performance for thousand achene mass, achene length, achene width, volume index and even a smaller diameter of missing seeds.

Maize genetic breeding for tolerance to abiotic stress with focus on sustainable use of environmental resources

2023-11-19T11:08:28-03:00

This bibliographic review explored maize genetic breeding to increase tolerance to abiotic stress. The main stresses faced by the crop, such as water stress and nitrogen deficiency, and their negative impacts on grain yield were discussed. Strategies to minimize these effects were examined, focusing on the selection of tolerant genotypes and the strategic positioning of these genotypes in different growing environments. The germplasm bank and genetic diversity were highlighted as crucial resources to identify desirable traits and genes associated with resistance to abiotic stress. The selection of secondary characters, considering their heritability and correlation with characters of interest, allows maximizing the efficiency in the selection of promising genotypes in genetic breeding programs. Test environments simulating stresses, such as water stress and low nitrogen, are essential to evaluate the performance of genotypes and identify the most tolerant ones. The genetic breeding of maize for tolerance to abiotic stress promotes promising solutions to face environmental challenges and ensure the sustainability of agricultural production.

Contamination by aerobic mesophilal and enterobacteriaceae bacteria in a pig refrigerator

2023-11-22T18:54:22-03:00

The study aimed to evaluate the knives, contact surfaces and carcasses for contamination by mesophilic aerobic bacteria and Enterobacteriaceae, in a pig slaughterhouse in the state of Rio Grande do Sul. The present study took place in a pig slaughterhouse, located in the Northwest Region of the State of Rio Grande do Sul, under the Federal Inspection Service (SIF). The experimental design used was randomized blocks organized in a bifactorial scheme, being for the knives: 3 (days of collection) x 3 x 15 (time of collection and knives from the slaughter and deboning process), totaling 135 experimental units for the knives. For water, main contact surfaces and pig carcasses, a unifactorial scheme was used: 3 (days of collection) x 12 surfaces (5 contact surfaces and 7 carcasses), totaling 36 experimental units. Knives used during slaughter operations are a form of contamination. There is deficiency in the pre-operational hygiene procedure of the utensils.

Environmental stimulus in lettuce genotype in agroecological cultivation system

2023-11-24T18:01:06-03:00

Vegetable production system has presented and developed strategies to increase the level of sustainability of production, adding information that expands agroecological production, resulting in better use of different components necessary for production. This study aims to evaluate the effect of different coverages in relation to the expression of the genotype in three crops of different agricultural years, enabling the best use of natural resources, bringing effective subsidies for a more sustainable production. The study was conducted in three growing seasons, in 2017, 2018 and 2019 crop years, in a randomized block design with four replications, using three soil covers (corn silage residue, elephant grass straw and soil without vegetation cover) and a lettuce cultivar (Lettuce “Iceberg”). It was possible to observe through the analysis of variance that only the year variable promoted alterations on the analyzed characters, with no effect of the different coverages. The highest production occurred in 2019 for all variables analyzed. Regarding the estimate of Pearson's linear correlation, it was possible to obtain significance at 0.01% of probability for the variables average total weight and productivity, with a significance of 1% of probability for the variables average diameter, average longitudinal diameter and productivity. There was no effect of soil cover for the variables of lettuce production and productivity, possibly related to excess water from precipitation in 2017, 2018 and 2019. In addition, the complementary effect of irrigation in the years of the experiment was, possibly, superior to the demand of the crop by reducing the effect of ground cover on soil water dynamics.

Enhancing the efficiency and sustainability of foliar fertilization in agriculture

2023-12-20T00:39:54-03:00

When considering foliar fertilization, many questions arise about the differences between chelation, complexation, and their efficiency in supplying nutrients to plants. How efficiently are chelated and complexed nutrients absorbed by plants? Are chelates and complexes absorbed by plants? How do they perform in foliar and soil applications? Do they exhibit greater efficiency when compared to pure inorganic fertilizers? and, which ones are the best: soluble, sparingly soluble, or insoluble inorganic fertilizers? Although many people believe chelation and complexation are similar, some differences must be considered when choosing products to better supply plants with nutrients, avoid problems with tank mixtures, and enhance plant nutrition efficiency. The same is true for the vast variety of inorganic sources of fertilizers available for agriculture. They do not behave the same. For instance, inorganic water-soluble fertilizers such as nitrates, sulfates, and chlorides present different performances and should be chosen not only based on their nutrient concentration, availability, and price. All this information will assist farmers and technicians in better defining and selecting products to improve sustainability, efficiency, and achieve better results.