Methods for assessment of pre-harvest sprouting in wheat cultivars

Abstract

-The objective of this work was to test methods for pre-harvest sprouting assessment in wheat cultivars. Fourteen wheat cultivars were grown in Londrina and Ponta Grossa municipalities, Paraná state, Brazil. They were sampled at 10 and 17 days after physiological maturity and evaluated using the methods of germination by rainfall simulation (in a greenhouse), in-ear grain sprouting, and grains removed from the ears. The in-ear grain sprouting method allowed the differentiation of cultivars, but showed different resistance levels from the available description of cultivars. The sprouting of grain removed from the ears did not allow a reliable distinction of data on germination in any harvest date or location. The method of rainfall simulation is the most suitable for the assessment of cultivars as to pre-harvest sprouting, regardless of the sampling date and evaluated location.Index terms: Triticum aestivum, dormancy, grain quality, rainfall simulation. Métodos de avaliação da germinação na pré-colheita em cultivares de trigoResumo -O objetivo deste trabalho foi testar métodos para avaliação da germinação na pré-colheita de cultivares de trigo. Quatorze cultivares de trigo foram cultivadas em Londrina e Ponta Grossa, PR. Aos 10 e 17 dias após a maturidade fisiológica, elas foram colhidas e avaliadas pelos métodos de germinação por simulação de chuva (em casa de vegetação), com grãos nas espigas e com grãos removidos das espigas. O método do grão na espiga permitiu a diferenciação das cultivares, porém mostrou graus de resistência distintos das descrições disponíveis para as cultivares. O procedimento do grão removido da espiga não possibilitou a distinção segura dos dados obtidos quanto à germinação, em qualquer época ou local de coleta. O método por simulação de chuva é o mais adequado para avaliação de cultivares quanto à germinação na pré-colheita, independentemente da época de coleta e do local avaliado.Termos para indexação: Triticum aestivum, dormência, qualidade do grão, simulação de chuva.

Alternative treatment to stimulate the germination of recently harvested wheat seeds

“…It is known that many wheat genotypes are dormant (Bojovic, 2010;Gu et al, 2010;Tunes et al, 2011;Gavazza et al, 2012;Liu et al, 2013;Gao and Ayele, 2014), and this behavior may hide information on the presence of feasible seeds in the germination test. In this sense, firms created procedures that allow overcoming Journal of Seed Science, v.38, n.4, p. [344][345][346][347][348][349]2016 the dormancy of recently harvested seeds, obtaining reliable information about the germination potential.…”

“…Analyzing all information, it is possible to observe that dormancy is common in most tested wheat genotypes, some with higher intensity than others. On one hand, this dormancy is desired because it avoids viviparity, which brings damages to seed and grain producers (Franco et al, 2009;Tunes et al, 2011;Gavazza et al, 2012;Gao and Ayele, 2014); on the other hand, there are also companies that need to obtain, in a simple and effective way, the germination percentage of recently harvested seeds, in order to make decisions on the allocation of lots. In this sense, a two-day reduction in the process required to overcome dormancy makes the system more agile, as well as increasing the operational capacity of laboratories.…”

“…However, when performed on recently harvested wheat seeds, values do not generally relate to the ones obtained during pre-seeding. This occurs because many wheat genotypes present dormant seeds right after harvesting, in variable intensities (Gavazza et al, 2012;Gao and Ayele, 2014).…”

“…In the physiological dormancy, the embryo, despite being physically complete, does not resume its growth after reaching its physiological maturity, especially because of factors related to hormonal balance or to the presence of inhibiting chemical compounds (Liu et al, 2013;Gao and Ayele, 2014;Nonokagi, 2014); it is important to highlight that dormancy is considered a genetically desirable attribute in commercialized wheat genotypes, and that it presents high heritability in segregant populations, that is, it is transmitted to descendents (Gu et al, 2010;Tunes et al, 2011;Gavazza et al, 2012) since these genotypes do not present viviparity. Overcoming dormancy in these seeds involves hormonal changes in the embryo, such as the increase in germination promoter concentrations (Tunes et al, 2011;Marcos-Filho, 2015).…”

Tolerance to preharvest sprouting and yield of wheat genotypes from different breeding programs

“…The premature germination of seeds while still attached to the mother plant decreases flour quality, turning starch into sugars (Kulwal et al, 2012), which makes the flour unsuitable for the baking process (Emebiri et al, 2010;Gavazza et al, 2012). In Brazil, PHS is very severe and, in bad years, the losses could reach more than US$100 million (Bassoi & Flintham, 2005).…”