Revista de la Facultad de Agronomía de la Universidad del Zulia

Morpho-agronomic characterization of native maize populations (Zea mays L.), province of Manabí, Ecuador

Wilson Murillo — 2024-09-16

Ecuador is a country with a wide genetic diversity of maize and there are populations of native maize conserved by farmers that have not yet been characterized. These genetic resources could be conserved and used in plant breeding programs. The objective of this research was to characterize the morpho-agronomic diversity of 38 populations of native maize from the province of Manabí, Ecuador, using 19 quantitative and 11 qualitative morpho-agronomic descriptors. During the dry season of 2022 (July - December) at the Portoviejo Experimental Station of the National Institute of Agricultural Research (INIAP), plots of 8 m² were established for each population of native maize, with 0.3 m between plants and 0.8 m between furrows and each furrow was 5 m long. Cluster analysis showed the formation of four groups, where the populations of hard kernels with large ears and soft kernels with short ears were separated into different groups. The quantitative variables ear height, panicle length, percentage of lodging, number of kernels per row and biomass of the inflorescence rachis recorded "D" indices of 0.75, showing themselves as discriminant variables in the formation of the groups, while the most discriminating qualitative variables were kernel type (χ2 = 49.09***, P= 0.742, V= 0.64), kernel color (χ2= 51.955***, P= 0.75, V=0.64), row arrangement (χ2= 18.11*, P=0.56, V=0.39), and kernel surface shape (χ2 = 20.52*, P=0.58, V=0.41). The native maize races identified were Candela, Cubano, Tuxpeño, Tusilla, and Uchima, observing significant genetic diversity in the populations studied. It was concluded that the characterized native maize populations were a valuable genetic resource for the conservation and use of this cereal.

Comparison of weed control methods in rice in the rainy and dry seasons

Byron García — 2024-09-16

Integrated weed management strategies are crucial to reduce crop production costs. The objective was to compare weed control techniques according to their efficiency and profitability in rice cultivation during the rainy and dry seasons. It was carried out under the quasi-experimental modality with the Student's t-test under a descriptive research type. Structured questionnaires were administered to 70 rice farmers in the area. Weeds were identified in areas every 10 m² within the rice crop, 10 and 15 days after sowing. The efficiency (E) of weed management in rice crops was calculated by applying the formula . The results showed that manual weeding has a monthly frequency, being used both in the rainy season (40 %) and in the dry season (44 %). The frequency of herbicide application was adjusted to the crop stage in the rainy season (39 %) and in the dry season (46 %). The efficiency (E) using the mechanical method was below one month during the rainy and dry seasons, registering 43%. Manual weeding showed an E of 49 % in the rainy season and 42 % in the dry season for up to 30 days. The combination of herbicides: Metsulfuron-methyl + Quinclorac; pyrazosulfuron-ethyl + Quinclorac, exhibited an E greater than 80 %, for more than 30 days in both seasons. The highest profitability was in the rainy season, thus presenting mechanized control USD 0.09 in rainfall and USD 0.04 in drought, chemical control USD 0.09 in rainfall and USD 0.07 in drought, and manual weeding USD 0.10 in rainfall and USD 0.06 in drought, for every dollar spent during the cultivation of rice.

Morphological response of native maize (Zea mays L.) seedlings to contrasting nitrogen environments

Jenaro Reyes-Matamoros — 2024-09-16

Nitrogen plays a vital role in plant metabolism, influencing growth and development, particularly in crops like maize (Zea mays L.). This study aimed to evaluate the morphological response of maize seedlings to different nitrogen levels. The design was a completely randomized factorial arrangement of 4 x 2, involving four maize cultivars and two nitrogen levels.The variety Sb 302 Berentsen and three native varieties originating from Tecamachalco, Puebla, Mexico were studied. For a period of 14, 21, 28 and 35 days, seedlings were grown in nutrient solution with 10 % and 100 % nitrogen levels under hydroponic conditions. The results revealed significant variability in seedling morphology, particularly in root architecture and dry weight, between the 10 % and 100 % nitrogen treatments. High coefficients of variation were observed in the lengths of crown and seminal roots, alongside significant correlations between root and seedling dry weights at both nitrogen levels. Additionally, a strong correlation was found between root length and number under the 10 % nitrogen treatment. The results highlight the critical role of nitrogen in maize seedling development and the interaction between nitrogen concentration and maize variety, particularly in primary root length. The study improves understanding of nitrogen's role in optimizing maize growth and suggests strategies to enhance nitrogen use efficiency across different maize varieties.