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Linear relationships in sunflower genotypes in the state of Rio Grande do Sul, Brazil

Relações lineares em genótipos de girassol no estado do Rio Grande do Sul, Brasil

ABSTRACT:

The state of Rio Grande do Sul (RS) is the third largest sunflower producer in Brazil. This study verified the existence of linear relationships between grain yield, oil content, and oil yield in sunflower (Helianthus annuus L.) genotypes evaluated in RS. The data on grain yield (GY), oil content (OC), and oil yield (OY) were obtained from 73 sunflower cultivar trials in 21 municipalities in RS from 1999 to 2018. Scatter diagrams were createdto investigate the relationships between the variables GY, OC, and OY. Then, Pearson’s linear correlation coefficient (r) was calculated between the variables, and the Student’s t-test was performed at a 5% significance level. There is a positive and significant linear relationship between PG and OY. However, no linear relationship was found between grain yield and oil content in sunflower genotypes. Additionally, a positive linear association of high magnitude (r = 0.9672) was observed between grain yield and oil yield, while a low magnitude (r = 0.2245) was found between oil content and oil yield.

Key words:
Helianthus annuus L.; grain yield; oil content; oil yield; correlation.

RESUMO:

O estado do Rio Grande do Sul (RS) é o terceiro maior produtor de girassol do Brasil. O objetivo deste trabalho foi verificar se há relações lineares entre a produtividade de grãos, teor de óleo e produtividade de óleo em genótipos de girassol (Helianthus annuus L.), avaliados no RS. Foram utilizados os dados de produtividade de grãos (PG), teor de óleo (TO) e produtividade de óleo (PO), obtidos em 73 ensaios de competição de cultivares de girassol em 21 municípios do RS, no período de 1999 a 2018. Para investigar as relações entre as variáveis PG, TO e PO foram construídos diagramas de dispersão. Depois, foi calculado o coeficiente de correlação linear de Pearson (r) entre as variáveis e realizado o teste t de Student, a 5% de significância. Há relação linear positiva e significativa entre PG e PO. Não há relação linear entre produtividade de grãos e teor de óleo em genótipos de girassol. Há associação linear positiva de alta magnitude (r = 0,9672) entre a produtividade de grãos e de óleo e de baixa magnitude (r = 0,2245) entre teor e produtividade de óleo.

Palavras-chave:
Helianthus annuus L.; produtividade de grãos; teor de óleo; produtividade de óleo; correlação.

INTRODUCTION

Sunflower (Helianthus annuus L.) is an oilseed plant of global importance. The oil produced from achenes is one of the main vegetable oils used in the human diet due to its nutritional quality. The average Brazilian sunflower grain yield in the 2020/2021 and 2021/2022 crop seasons was 1143 kg ha−1 and 1042 kg ha−1, respectively (CONAB, 2022COMPANHIA NACIONAL DE ABASTECIMENTO (CONAB). Acompanhamento da Safra Brasileira. Safra 2021/22 - N.9, junho, 2022. Brasília: CONAB , 2022. Available from: <Available from: https://www.conab.gov.br/info-agro/safras/graos/boletim-da-safra-de-graos >. Accessed: Feb. 20, 2023.
https://www.conab.gov.br/info-agro/safra...
). This productivity can be considered low compared to other sunflower-producing countries (SOARES et al., 2019SOARES, M. M. et al. Effects of competition and water deficiency on sunflower and weed growth. Revista Caatinga, v.32, n.2, p.318-328, 2019. Available from: <Available from: https://www.scielo.br/j/rcaat/a/cySPS3HVSn3wpbvZMbzYwrs/?lang=en >. Accessed: Mar. 14, 2023. doi:10.1590/1983-21252019v32n204rc.
https://www.scielo.br/j/rcaat/a/cySPS3HV...
). Sunflower cultivation in Brazil is concentrated in the South, Southeast, and Midwest regions. Rio Grande do Sul is the third-largest producing state, with production of 4.7 thousand tons (CONAB, 2023COMPANHIA NACIONAL DE ABASTECIMENTO (CONAB). Acompanhamento da Safra Brasileira. Safra 2022/23 - N.5, fevereiro, 2023. Brasília: CONAB, 2023. Available from: <Available from: https://www.conab.gov.br/info-agro/safras/graos >. Accessed: Feb. 23, 2023.
https://www.conab.gov.br/info-agro/safra...
).

Sunflower grain yield can be influenced by several factors, notably climate conditions, phytosanitary and soil management, and cultivars (NOBRE et al., 2015NOBRE, D. A. C. et al. Quality of sunflower seeds of different genotypes. Ciência Rural, v.45, n.10, p.1729-1735, 2015. Available from: <https://www.scielo.br/j/cr/a/JpRx7MFVsvFPC6VSrThdxXh/?lang=pt>. Accessed: Mar. 12, 2023. doi: 10.1590/0103-8478cr20120863.
https://www.scielo.br/j/cr/a/JpRx7MFVsvF...
; HIOLANDA et al., 2018HIOLANDA, R. et al. Contribution to the study of the agronomic performance of hybrids in the main sunflower producing region in Brazil (Chapadão do Parecis). Revista de Ciências Agrárias, v.41, n.1, p.11-20, 2018. Available from: <Available from: https://revistas.rcaap.pt/index.php/rca/article/view/16619 >. Accessed: Feb. 22, 2023. doi:10.19084/RCA17159.
https://revistas.rcaap.pt/index.php/rca/...
). The adoption of cultivars with better adaptability to the productive environment provides an increase in the crop’s grain yield (BIRCK et al., 2017BIRCK, M. et al. Performance of sunflower cultivars at different seeding periods in central Brazil. Ciência e Agrotecnologia, v.41, n.1, p.42-51, 2017. Available from: <Available from: https://www.scielo.br/j/cagro/a/gFyt4ShdbcGBZrM9R5HWg4t/?format=pdf⟨=en >. Accessed: Mar. 13, 2023. doi: 10.1590/1413-70542017411021216.
https://www.scielo.br/j/cagro/a/gFyt4Shd...
; DALCHIAVON et al., 2016DALCHIAVON, F. C. et al. Agronomic traits and their correlations in sunflower hybrids adapted to second crop. Pesquisa Agropecuária Brasileira, v.51, n.11, p.1806-1812, 2016. Available from: <Available from: https://www.scielo.br/j/pab/a/CyLQqDk9z3yjd9pvgBTvk6K/?lang=pt# >. Accessed: Feb. 22, 2023. doi: 10.1590/S0100-204X2016001100002.
https://www.scielo.br/j/pab/a/CyLQqDk9z3...
). To this end, experiments with new hybrids, developed each year, need to be conducted to identify the most adapted genotypes and verify how these hybrids respond together in productive terms, aiming for new progress in the genetic improvement of the species (OLIVEIRA et al., 2017OLIVEIRA, S. L. de. et al. Phenotypic dissimilarity in sunflower genotypes cultivated in nor-thern Minas Gerais. Agri-Environmental Sciences, v.3, n.2, p.19-28, 2017. Available from: <Available from: https://revista.unitins.br/index.php/agri-environmental-sciences/article/view/434 >. Accessed: Feb. 22, 2023. doi: 10.36725/agries.v3i2.434.
https://revista.unitins.br/index.php/agr...
).

Trial networks play an important role in the positioning of cultivars. Current studies focused on evaluating the performance of sunflower cultivars have prioritized not only grain yield and oil yield (THOMAZ et al., 2012THOMAZ, G. L. et al. Yield of sunflower and oil seed content as a function of air temperature, rainfall and solar radiation. Ciência Rural, v.42, n.8, p.1380-1385, 2012. Available from: <Available from: https://www.scielo.br/j/cr/a/w83KNZ3wHXfqC3vmMfwLk7s/abstract/?lang=pt >. Accessed: Mar. 12, 2023. doi: 10.1590/S0103-84782012000800008.
https://www.scielo.br/j/cr/a/w83KNZ3wHXf...
; SCHWERZ et al., 2015SCHWERZ, T. et al. Sunflower production grown after soybeans, corn and palisade grass, with and without supplemental irrigation. Revista Brasileira de Engenharia Agrícola e Ambiental, v.19, p.470-475, 2015. Available from: <Available from: https://www.scielo.br/j/rbeaa/a/ZTkTPfwkfh.cG6LZLWtDjKpq/?lang=pt >. Accessed: Feb. 23, 2023. doi: 10.1590/1807-1929/agriambi.v19n5p470-475.
https://www.scielo.br/j/rbeaa/a/ZTkTPfwk...
; DALCHIAVON et al., 2016DALCHIAVON, F. C. et al. Agronomic traits and their correlations in sunflower hybrids adapted to second crop. Pesquisa Agropecuária Brasileira, v.51, n.11, p.1806-1812, 2016. Available from: <Available from: https://www.scielo.br/j/pab/a/CyLQqDk9z3yjd9pvgBTvk6K/?lang=pt# >. Accessed: Feb. 22, 2023. doi: 10.1590/S0100-204X2016001100002.
https://www.scielo.br/j/pab/a/CyLQqDk9z3...
) but also oil content (SCHWERZ et al., 2015SCHWERZ, T. et al. Sunflower production grown after soybeans, corn and palisade grass, with and without supplemental irrigation. Revista Brasileira de Engenharia Agrícola e Ambiental, v.19, p.470-475, 2015. Available from: <Available from: https://www.scielo.br/j/rbeaa/a/ZTkTPfwkfh.cG6LZLWtDjKpq/?lang=pt >. Accessed: Feb. 23, 2023. doi: 10.1590/1807-1929/agriambi.v19n5p470-475.
https://www.scielo.br/j/rbeaa/a/ZTkTPfwk...
; DALCHIAVON et al., 2016DALCHIAVON, F. C. et al. Agronomic characteristics of sunflower (Helianthus annuus L.) genotypes second crop in the Chapadão do Parecis - MT. Revista de Ciências Agrárias, v.39, p.178-186, 2016. Available from: <Available from: https://revistas.rcaap.pt/rca/article/view/16367 >. Accessed: Feb. 22, 2023. doi: 10.19084/RCA15049.
https://revistas.rcaap.pt/rca/article/vi...
). It can be important when choosing cultivars, as grain yield is a multigenic trait, and factors such as lack of water availability, associated with the vegetative cycle, can be essential for grain yield.

Increasing the sunflower seed oil content, as well as improving its quality, making it compatible with industrial demands, is an important objective of the genetic improvement of the crop (RAUF et al., 2017RAUF, S. et al. Progress in modification of sunflower oil to expand its industrial value. Journal of the Science of Food and Agriculture, v.97, n.7, p.1997-2006, 2017. Available from: <Available from: https://pubmed.ncbi.nlm.nih.gov/28093767/ >. Accessed: Mar. 12, 2023. doi: 10.1002/jsfa.8214.
https://pubmed.ncbi.nlm.nih.gov/28093767...
). There is evidence of interest in genotypes with high grain and oil yield, associated with a high oil content that provides better industrial efficiency for its extraction.

However, when considering various environments under study, there is a probability of different productive responses of grains and oil due to the interaction between genotype and environment, requiring the continuous evaluation of new materials in different cultivation systems and producing regions (VALADÃO et al., 2020VALADÃO, F. C. A. et al. Sunflower productivity in function of the management of nitrogen fertilization. Brasilian Jornal of Development, v.6, n.11, p.84197-84213, 2020. Available from: <Available from: https://ojs.brazilianjournals.com.br/ojs/index.php/BRJD/article/view/19267/15459 >. Accessed: Feb. 24, 2023. doi: 10.34117/bjdv6n10-744.
https://ojs.brazilianjournals.com.br/ojs...
). Studies on linear relationships in sunflower cultivation have been conducted by authors such as AMORIM et al. (2008AMORIM, E. P. Correlations and path analysis in sunflower. Bragantia, v.67, n.2, p.307-316, 2008. Available from: <Available from: https://www.scielo.br/j/brag/a/9vNbJDSrknpPJspBbZLrxNt/?format=pdf⟨=pt >. Accessed: Feb. 24, 2023. doi: 10.1590/S0006-87052008000200006.
https://www.scielo.br/j/brag/a/9vNbJDSrk...
), DALCHIAVON et al. (2016DALCHIAVON, F. C. et al. Agronomic traits and their correlations in sunflower hybrids adapted to second crop. Pesquisa Agropecuária Brasileira, v.51, n.11, p.1806-1812, 2016. Available from: <Available from: https://www.scielo.br/j/pab/a/CyLQqDk9z3yjd9pvgBTvk6K/?lang=pt# >. Accessed: Feb. 22, 2023. doi: 10.1590/S0100-204X2016001100002.
https://www.scielo.br/j/pab/a/CyLQqDk9z3...
), and HLADNI et al. (2016HLADNI, N. et al. Correlation and path analysis of yield and yield components of confectionary sunflower. Genetika, v.48, n.3, p.827-835, 2016. Available from: <Available from: https://www.researchgate.net/publication/314108281_Correlation_and_path_analysis_of_yield_and_yield_components_of_confectionary_sunflower >. Accessed: Feb. 21, 2023. doi: 10.2298/GENSR1603827H.
https://www.researchgate.net/publication...
). The presence or absence of correlations between these traits can contribute to the right choice of the observed characteristics to improve the efficiency of sunflower genotype selection criteria (RADIC, 2021RADIC, V. et al. Correlation and path analysis of yield and yield components in winter rapeseed. Genetika, v.53, n.1, p.157-166, 2021. Available from: <Available from: https://www.researchgate.net/publication/351876997_Correlation_and_path_analysis_of_yield_and_yield_components_in_winter_rapeseed >. Accessed: Feb. 22, 2023. doi: 10.2298/GENSR2101157R.
https://www.researchgate.net/publication...
). Therefore, knowledge of the relationships between traits is of paramount importance for plant improvement studies in sunflower cultivation (NOBRE et al., 2018NOBRE, D. A. C. et al. Path analysis and canonical correlation in components of the sunflower performance. The Journal of Engineering and Exact Sciences, v.4, n.3, p.364-369, 2018. Available from: <Available from: https://periodicos.ufv.br/jcec/article/view/2524 >. Accessed: Mar. 12, 2023. doi: 10.18540/jcecvl4iss3pp0364-0369.
https://periodicos.ufv.br/jcec/article/v...
).

In this context, this study verified whether there are linear relationships between grain yield, oil content, and oil yield in sunflower (Helianthus annuus L.) genotypes evaluated in the state of Rio Grande do Sul, Brazil.

MATERIALS AND METHODS

Data on grain yield (GY, in kg ha−1), oil content (OC, in %), and oil yield (OY, in kg ha−1) from 281 sunflower (Helianthus annuus L.) genotypes were used in 73 trials from the evaluation testing network (Table 1). The trials were conducted in 21 locations in the state of Rio Grande do Sul from 1999 to 2018 (Table 1 and Figure 1).

Table 1
Number of trials in each location and year and total trials per location and year conducted in the sunflower (Helianthus annuus L.) genotype testing network from 1999 to 2018 in the state of Rio Grande do Sul, Brazil. Number of genotypes evaluated each year.

Figure 1
Geographic representation of 21 locations where the sunflower genotype testing network was conducted from 1999 to 2018in the state of Rio Grande do Sul, Brazil.

The data were obtained from reports on the evaluation of sunflower genotypes published annually by the Brazilian Agricultural Research Corporation (EMBRAPA) (Table 2). The reports are published annually and result from the cooperation of universities and research institutions, which collaborate with the national sunflower testing network (CARVALHO et al., 2022CARVALHO, C. G. P. et al. Informes da avaliação de genótipos de girassol 2021/2022 e 2022. Brasília: EMBRAPA, 2022. 54p. Available from: <Available from: http://www.infoteca.cnptia.embrapa.br /infoteca/handle/doc/1151014 >. Accessed: Mar. 10, 2023.
http://www.infoteca.cnptia.embrapa.br /i...
).

Table 2
List of documents published annually by the Brazilian Agricultural Research Corporation (EMBRAPA) in partnership with public and private institutions, referring to the sunflower (Helianthus annuus L.) genotype testing network from 1999 to 2018 in the state of Rio Grande do Sul, Brazil.

All trials were conducted in a randomized block design, with four replications. The experimental units consisted of four rows spaced 0.5 m wide and 6.0 m long. The area of the plots was 12.0 m2, with a useful area of 5.0 m2.

Minimum, percentiles 1, 2.5, 25, 50 (median), 75, 97.5, and 99, maximum, range, mean, variance, standard deviation, standard error, coefficients of variation, skewness, kurtosis, and P-value of the Kolmogorov-Smirnov normality test were calculated for the three variables (GY, OC, and OY) evaluated in all genotypes of the 73 trials (1,137 observations). The means of GY, OC, and OY were also calculated per agricultural year regardless of the location and per location regardless of the agricultural year.

Scatter diagrams were created to investigate the relationships between the variables GY, OC, and OY. Subsequently, Pearson’s linear correlation coefficient (r) was calculated between the variables and Student’s t-test was performed at a 5% significance.

Statistical analyses were conducted using the Microsoft Office Excel® and Genes applications (CRUZ, 2016CRUZ, C. D. Programa Genes - Ampliado e integrado aos aplicativos R, Matlab e Selegen. Acta Scientiarum Agronomy, v.38, n.4, p.547-552, 2016. Available from: <Available from: https://www.scielo.br/j/asagr/a/sLvDYF5MYv9kWR5MKgxb6sL/?lang=en >. Accessed: Fev. 22, 2023. doi: 10.4025/actasciagron.v38i4.32629.
https://www.scielo.br/j/asagr/a/sLvDYF5M...
).

RESULTS AND DISCUSSION

The minimum and maximum values of GY, OC, and OY of the genotypes evaluated in the 73 trials ranged from 375.90 to 4484.00 kg ha−1, 20.34 to 53.42%, and 160.11 to 1913.76 kg ha−1, respectively (Table 3). CV ranged from 8.37 to 34.92%, with the highest CV observed in GY and OY. Similarly, LIRA et al. (2017LIRA, E. G. Genetic parameters, phenotypic, genotypic and environmental correlations and genetic variability on sunflower in the Brazilian Savannah. Ciência Rural, v.47, n.8, e20160719, 2017. Available from: <Available from: https://www.scielo.br/j/cr/a/kLCrNVKKHzNpSGfbK7PKXnx/?lang=en >. Accessed: Mar. 15, 2023. doi: 10.1590/0103-8478cr20160719.
https://www.scielo.br/j/cr/a/kLCrNVKKHzN...
) and DALCHIAVON et al. (2016DALCHIAVON, F. C. et al. Agronomic traits and their correlations in sunflower hybrids adapted to second crop. Pesquisa Agropecuária Brasileira, v.51, n.11, p.1806-1812, 2016. Available from: <Available from: https://www.scielo.br/j/pab/a/CyLQqDk9z3yjd9pvgBTvk6K/?lang=pt# >. Accessed: Feb. 22, 2023. doi: 10.1590/S0100-204X2016001100002.
https://www.scielo.br/j/pab/a/CyLQqDk9z3...
) found higher variation in GY and OY and lower variation in OC.

Table 3
Number of observations, minimum, percentiles 1, 2.5, 25, 50 (median), 75, 97.5, and 99, maximum, range, mean, variance, standard deviation, standard error, coefficient of variation (CV), skewness, kurtosis, and P-value of the Kolmogorov-Smirnov normality test of variables evaluated in sunflower (Helianthus annuus L.) genotypes from 1999 to 2018 in the state of Rio Grande do Sul, Brazil.

The mean of the variables was similar to the median, and the coefficient of skewness was close to zero (−0.67 ≤ skewness ≤ 0.39). The coefficient of kurtosis for GY and OY was −0.22 and 0.02, respectively, indicating a mesokurtic distribution, while OC presented a leptokurtic distribution. The Kolmogorov-Smirnov test indicated adherence of data for all variables to a normal distribution (P-value ≥ 0.05). Therefore, the statistical results showed that the data is representative of the study of linear relationships.

The mean GY and OY in the 20 agricultural years ranged from 1450.02 to 2798.49 kg ha−1 and 623.18 to 1205.13 kg ha−1, respectively (Table 4). The lowest means for these variables were observed in 2010/2011, while the highest means were observed in 2003/2004 (Table 4). It indicates that higher GY means are related to higher OY. OC presented higher mean magnitudes in 2000/2001 (46.12%), with smaller variations between the means, with the lowest performance observed in 2001/2002 (37.46%). The results of GY, OC, and OY are consistent with values observed in other studies with sunflower cultivation (DALCHIAVON et al., 2016DALCHIAVON, F. C. et al. Agronomic traits and their correlations in sunflower hybrids adapted to second crop. Pesquisa Agropecuária Brasileira, v.51, n.11, p.1806-1812, 2016. Available from: <Available from: https://www.scielo.br/j/pab/a/CyLQqDk9z3yjd9pvgBTvk6K/?lang=pt# >. Accessed: Feb. 22, 2023. doi: 10.1590/S0100-204X2016001100002.
https://www.scielo.br/j/pab/a/CyLQqDk9z3...
; CARVALHO et al., 2015CARVALHO, C. G. P. Adaptability and stability of sunflower genotypes imidazolinone resistant in second crop cultivation. Revista Brasileira de Ciências Agrárias, v.10, n.1, p.1-7, 2015. Available from: <Available from: http://www.agraria.pro.br/ojs32/index.php/RBCA/article/view/v10i1a3804/593 >. Accessed: Feb. 23, 2023. doi: 10.5039/agraria.v10i1a3804.
http://www.agraria.pro.br/ojs32/index.ph...
).

Table 4
Means of grain yield, oil content, and oil yield of sunflower (Helianthus annuus L.) genotypes per agricultural year evaluated from 1999 to 2018 in 21 locations in the state of Rio Grande do Sul, Brazil.

The overall means of GY, OC, and OY of the sunflower genotypes in the 20 years of trials was 2030.24 kg ha−1, 42.91%, and 870.83kg ha−1, respectively. According to CONAB (2023), the national mean of sunflower grain yield in the 2022/2023 crop season was 1436 kg ha−1. Therefore, the overall mean of GY in the study was higher than the national mean. The evaluated variables showed means with a low variation in the last six years of testing. Furthermore, GY means were higher than 2000 kg ha−1 in this same period. It indicated higher stability and potential of the new genotypes and higher efficiency in the used management.

The highest means of GY were observed in Pelotas and Palmeira das Missões (Table 5), which presented values above 3000 kg ha−1, followed by Caxias do Sul, which hada mean of 2859.25 kg ha−1. These values are higher than those found by DALCHIAVON et al. (2016DALCHIAVON, F. C. et al. Agronomic traits and their correlations in sunflower hybrids adapted to second crop. Pesquisa Agropecuária Brasileira, v.51, n.11, p.1806-1812, 2016. Available from: <Available from: https://www.scielo.br/j/pab/a/CyLQqDk9z3yjd9pvgBTvk6K/?lang=pt# >. Accessed: Feb. 22, 2023. doi: 10.1590/S0100-204X2016001100002.
https://www.scielo.br/j/pab/a/CyLQqDk9z3...
), who obtained maximum yields of 2259 kg ha−1 in experiments with 16 cultivars and 10 experimental locations.

Table 5
Means of grain yield, oil content, and oil yield of sunflower (Helianthus annuus L.) genotypes per location evaluated from 1999 to 2018 in 21 locations in the state of Rio Grande do Sul, Brazil.

The oil content, with the same magnitude of importance for sunflower cultivation, had a similar response: the highest means were verified in Pelotas, Encruzilhada do Sul, and Caxias do Sul, with values of 46.40, 45.61, and 44.15%, respectively. These values are higher than the mean values (43.6%) found by DALCHIAVON et al. (2016DALCHIAVON, F. C. et al. Agronomic traits and their correlations in sunflower hybrids adapted to second crop. Pesquisa Agropecuária Brasileira, v.51, n.11, p.1806-1812, 2016. Available from: <Available from: https://www.scielo.br/j/pab/a/CyLQqDk9z3yjd9pvgBTvk6K/?lang=pt# >. Accessed: Feb. 22, 2023. doi: 10.1590/S0100-204X2016001100002.
https://www.scielo.br/j/pab/a/CyLQqDk9z3...
) and GRUNVALD et al. (2014GRUNVALD, A. K. et al. Adaptability and stability of conventional and high oleic sunflower genotypes cultivated in southern Brazil. Revista de Ciências Agrárias, v.57, n.3, p.217-223, 2014. Available from: <https://doi.editoracubo.com.br/10.4322/rca.ao1270>. Accessed: Feb. 22, 2023. doi: 10.4322/rca.ao1270.). Therefore, among the locations with higher grain yield and oil content, only the experimental sites of Palmeira das Missões and Encruzilhada do Sul showed changes.

Moreover, Pelotas and Caxias do Sul presented the highest oil yield, followed by Palmeira das Missões, with values of 1475.93, 1263.80, and 1257.22 kg ha−1, respectively. DALCHIAVON et al. (2016DALCHIAVON, F. C. et al. Agronomic traits and their correlations in sunflower hybrids adapted to second crop. Pesquisa Agropecuária Brasileira, v.51, n.11, p.1806-1812, 2016. Available from: <Available from: https://www.scielo.br/j/pab/a/CyLQqDk9z3yjd9pvgBTvk6K/?lang=pt# >. Accessed: Feb. 22, 2023. doi: 10.1590/S0100-204X2016001100002.
https://www.scielo.br/j/pab/a/CyLQqDk9z3...
) observed higher values, with a maximum yield of 1012 kg ha−1.

It is justified by the fact that these locations have high sunflower grain yield values and high oil contents than other experimental locations. However, almost all the mentioned locations had experiments in only one growing season, except for Encruzilhada do Sul, where three years of experiments were carried out.

Thus, Pelotas and Caxias do Sul have considerable production potential for sunflower grains, while Encruzilhada do Sul has a high potential for oil content, as it presented a mean oil content of 45.61% in three years of experiments. This factor may be associated with environmental conditions, such as daytime and nighttime temperature fluctuations. According to THOMAZ et al. (2012THOMAZ, G. L. et al. Yield of sunflower and oil seed content as a function of air temperature, rainfall and solar radiation. Ciência Rural, v.42, n.8, p.1380-1385, 2012. Available from: <Available from: https://www.scielo.br/j/cr/a/w83KNZ3wHXfqC3vmMfwLk7s/abstract/?lang=pt >. Accessed: Mar. 12, 2023. doi: 10.1590/S0103-84782012000800008.
https://www.scielo.br/j/cr/a/w83KNZ3wHXf...
) and REGITANO NETO et al. (2016REGITANO NETO, A. et al. Environmental effect on sunflower oil quality. Crop Breeding and Applied Biotechnology, v.16, p.197-204, 2016. Available from: <Available from: https://www.scielo.br/j/cbab/a/WvVNTT9cKDxzpMFm3CpHkWg/?lang=en&format=pdf >. Accessed: Mar. 11, 2023. doi: 10.1590/1984-70332016v16n3a30.
https://www.scielo.br/j/cbab/a/WvVNTT9cK...
), higher mean temperatures lead to a decrease in oil content.

The variables GY and OC showed no significant correlation, indicating the non-existence of a variation trend for one variable relative to an increase or decrease of the other (Figure 2). In contrast, correlations were observed between OY and OC, which were significant and had a Pearson correlation coefficient of 0.2245.This result is similar but shows a smaller magnitude than that found by GHAFFARI et al. (2019GHAFFARI, M. et al. Oil yield determinant of sunflower in climatically different regions of Iran. Bulgarian Journal of Agricultural Science, v.25, p.67-71, 2019. Available from: <Available from: https://www.agrojournal.org/25/01-10.pdf >. Accessed: Mar. 10, 2023.
https://www.agrojournal.org/25/01-10.pdf...
), who obtained significant correlations for OY × OC of 0.72 and 0.64 in different experimental locations. However, OC established a non-significant correlation with GY, as observed by AMORIM et al. (2008AMORIM, E. P. Correlations and path analysis in sunflower. Bragantia, v.67, n.2, p.307-316, 2008. Available from: <Available from: https://www.scielo.br/j/brag/a/9vNbJDSrknpPJspBbZLrxNt/?format=pdf⟨=pt >. Accessed: Feb. 24, 2023. doi: 10.1590/S0006-87052008000200006.
https://www.scielo.br/j/brag/a/9vNbJDSrk...
).

Figure 2
Matrix with frequency histogram (on the diagonal) and scatter diagrams (off the diagonal) between grain yield (GY), oil content (OC), and oil yield (OY) of sunflower (Helianthus annuus L.) genotypes evaluated from 1999 to 2018 in the state of Rio Grande do Sul, Brazil. Pearson’s linear correlation coefficients (r) between variables and Student’s t-test P-value.

The correlation established between GY and OY leads to a response of increased oil yield, with an increase in sunflower grain yield and a significant positive correlation of 0.9672. DALCHIAVON et al. (2016DALCHIAVON, F. C. et al. Agronomic traits and their correlations in sunflower hybrids adapted to second crop. Pesquisa Agropecuária Brasileira, v.51, n.11, p.1806-1812, 2016. Available from: <Available from: https://www.scielo.br/j/pab/a/CyLQqDk9z3yjd9pvgBTvk6K/?lang=pt# >. Accessed: Feb. 22, 2023. doi: 10.1590/S0100-204X2016001100002.
https://www.scielo.br/j/pab/a/CyLQqDk9z3...
) also observed a positive and significant correlation for GY and OY.

Sunflower has the potential for cultivation in grain-producing regions in the state of Rio Grande do Sul even though there are variations in soil types and altitude between the northern and southern half of the state. It is not clear whether there is a trend toward a region with higher production potential for the crop over a period of 20 years, which may also be associated with the crop rusticity and ability to adapt to different soil types and environmental variables, particularly the air temperature, as higher altitudes predominate in the northern half of the state compared to the southern half of the state of Rio Grande do Sul.

CONCLUSION

Therefore, no linear relationship was observed between grain yield and oil content in sunflower genotypes in the state of Rio Grande do Sul. A positive linear association of high magnitude (r = 0.9672) was observed between grain yield and oil yield and of low magnitude (r = 0.2245) between oil content and oil yield.

ACKNOWLEDGMENTS

To researchers of the Empresa Brasileira de Pesquisa em Agropecuária (EMBRAPA) and other research institutions for carrying out these trials. We thank the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ), Processes number 304652/2017-2 and 304878/2022-7) .for the research productivity grant. The Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for granting scholarships and financial incentives to conduct this study

REFERENCES

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    CR-2023-0201.R1

DECLARATION OF CONFLICT OF INTERESTS

  • DECLARATION OF CONFLICT OF INTERESTS

    The authors declare no conflict of interest.

Publication Dates

  • Publication in this collection
    15 Apr 2024
  • Date of issue
    2024

History

  • Received
    14 Apr 2023
  • Accepted
    06 Dec 2023
  • Reviewed
    07 Mar 2024
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