Soybean growth, solar energy conversion and seed vigour affected by different nitrogen (N) doses

Abstract

The objective of this study was to evaluate soybean growth, conversion of solar energy and seed vigour of plants cultivated with different nitrogen doses. We carried out experiments using the cultivar BMX Potência RR belongs to the maturation group 6.7, presenting an indeterminate growth habit. The experimental design was completely randomised with four replications in a 4 x 8 factorial scheme (four nitrogen doses and eight collection periods). In the Vn stage of soybean development, we applied four different nitrogen fertilisation doses, i.e. 0, 25, 50 and 75 Kg N ha -1 in the form of urea (45% of N). We evaluated leaf area (A f ), leaf dry mass (W f ), stem (W c ), roots (W r ) and pods (W v ), dry matter production rate (C t ), relative growth rate (R w ), net assimilation (E a ), rate, leaf area ratio (S a ), solar energy conversion factor (ξ), leaf area ratio (F a ) and leaf mass (F w ), dry matter partition between plant structures, seedling emergence (E) and the emergence speed index (IVE) of the seedlings originated from the seeds produced. The experiment was conducted throughout the crop cycle. Nitrogen application positively impacted soybean growth; a nitrogen dose of 50 Kg ha -1 resulted in highest values of W t . However, plants subjected to 75 Kg N ha -1 reached higher R w and L values. Nitrogen fertilisation applied in the stage Vn facilitated plant growth, enhanced the conversion of solar energy and resulted in higher seed vigour. Keywords:Glycine max (L.); relative growth rate; net assimilation rate; emergence; emergence speed index. Abbreviations: A f _Leaf area, C t _Dry matter production rate, E a _Net assimilation rate, E_Emergence, F a _ Leaf area ratio, F w _And leaf mass, IVE_And the emergence speed index, L_Leaf area index, N_Nitrogen, R w _Relative growth rate, S a _Leaf area ratio, W c _Stem, W f _Leaf dry mass, W r _Roots, W v _And pods, ξ_Solar energy conversion factor.

Research Article Nitrogen supplementation improves yield and quality of soybean seeds

“…The vigor evaluated through the tetrazolium test revealed a positive effect resulting from the application of N in all treatments, with increments of up to 6.7%, if compared to the absence of N in coverage. In this sense, the results of this research corroborate those found by Aisenberg et al (2018), who, when evaluating the vigor by the seedling emergence velocity index, found out that seedlings from seeds under the influence of the application of N at the dose of 50 kg ha -1 reached higher values in 16.5, 11.4 and 19.1%, when compared to those under 0, 25 and 75 kg ha -1 of N, respectively.…”

“…For the emergence of seedlings in beds, all kinds of management with the application of N in coverage, regardless of the application stage, presented higher emergency values than 0R2/0R5, with increments of up to 5.2%, when the application of N was split between stages R2 and R5 (60R2/60R5). These results were lower than those observed by Aisenberg et al (2018), who observed increments of 12, 15 and 10% in the emergence of seedlings, for seeds from plants subjected to applications of 25, 50, and 75 kg of N ha -1 , respectively, and compared to the absence of N in coverage. In the same study, the emergence of seedlings presented a quadratic response to the different doses of N evaluated, with maximum emergence of seedlings at the estimated dose of 47.3 kg of N ha -1 , with a decreasing tendency for doses higher than this.…”

Chemical Control of Asian Soybean Rust and Its Effect in the Yield and Quality of Soybean Seeds

“…However, the values of the electrical conductivity test presented in the same table, infer that without application, an application and two applications treatments that do not differ statistically from each other, present statistical difference in relation to treatments three applications, four applications and five applications.Through the electrical conductivity data (Table 3) correlated with PMS and germination (Table 1), it can be inferred that the seeds that received the highest number of fungicide application had higher quality. This is justified by the fact that the increase of leachate solutes is directly related to the decrease in seed germination and vigor (Binotti et al, 2008;Aisenberg et al, 2018). Similar results were found by Pinto et al (2011), who did not observe a difference between the treatments for the accelerated aging test, and also found that seeds that did not receive fungicide application for the control of Asian rust obtained higher leaching of solutes, being considered of lower physiological quality.…”

Economic efficiency and soybean yield due to the use of different fungicide combinations

“…These groups act with different modes of action, distinct sites of action in pathogens, improve disease control and maintain the photosynthetic area of plants over time. Carboxamide is a specific site fungicide that acts on the inhibition of the enzyme Succinate dehydrogenase, this new chemical group showed better results than the other chemical groups in the control of Phakopsorapachyrhizi (Embrapa, 2014;Zanatta et al, 2018;Aisenberg et al, 2018). Dithiocarbamates are multi-site fungicides that act on several processes vital to pathogens, being an excellent tool to increase the efficiency of systemic fungicides and disease management (Silva, 2015;.…”