Effects of pre-harvest chemical application on rice desiccation and seed quality

Abstract

Pre-harvest desiccation may increase the efficiency of seed production. Field studies were conducted to determine the effects of diquat, paraquat, and ethephon applications on grain moisture, grain weight, and seed germination of hybrid rice Yanliangyou 88 (Oryza sativa ssp. indica) and conventional rice Wuyunjing 7 (Oryza sativa ssp. japonica). In 2013, we tested 12 treatments applied at four weeks (Yanliangyou 88) and six weeks (Wuyunjing 7) after heading. Results showed that reductions in moisture content were significant two and four days after chemical application. Chemical applications had no adverse effects on 1000-grain weight, germination percentage, or germination index, but there were negative effects on the percentage of normal seedlings. Desiccation effects increased with increase in the period after application, while the effect of ethephon combined with diquat or paraquat on desiccation was limited compared with that of diquat or paraquat alone in a short period after application. In 2013, chemical applications reduced the moisture content by from 0.5% to 6.4%, the germination percentage by from 0% to 3.3%, and the percentage of normal seedlings by from 13.3% to 100.0%. Among the treatments, diquat applied at 120 g/ha resulted in effective desiccation with fewer negative effects on grain weight and seed germination in 2013 and 2014. Therefore, diquat may have potential as a pre-harvest chemical desiccation treatment for rice. These results may provide a basis for developing and implementing protocols for large scale field trials.

Effects of Pre-Harvest Glyphosate Application on Spring Wheat Quality Characteristics

“…Similar observations, where harvest aids caused negative effects on grain quality, were found in other crops such as dry bean [24], sorghum seed [25], soybean [26], peas [27] and rice [28]. However, contrary to the findings of the current study, He et al [29], who studied the impact of the harvest aids, such as diquat, paraquat and ethephan on rice quality, reported that pre-harvest application of these herbicides did not affect the TKW of rice. Similar observations were made by Boudreaux and Griffin [30], who studied soybean.…”

Genome-wide association analysis of panicle exsertion and uppermost internode in rice (Oryza sativa L.)

“…The haplotypes containing at least 5 investigated accessions were used for comparative analysis (Wang et al 2015). Fisher’s least significant difference (LSD) test was conducted to compare the differences in PE, UI, and 1000-GW (He et al 2015).…”

Dessecação pré-colheita em sorgo granífero: qualidade fisiológica das sementes e efeito sobre a rebrota

“…De acordo com Azevedo et al (2015) o uso de paraquat não causa danos à semente de soja, desde que seja aplicado no estádio fenológico adequado. Por outro lado, em culturas como o arroz (He et al, 2015) e o trigo (Fipke et al, 2018) há estudos que mostram que o paraquat pode afetar a germinação das sementes e o desenvolvimento inicial das plântulas. Essa divergência com relação ao uso do paraquat se deve ao fato de existir uma forte relação do estágio de aplicação e das condições ambientais (temperatura, luminosidade, etc) que sucedem a aplicação sobre os efeitos do produto sobre a semente (Bezerra et al, 2016).…”

“…O uso de dessecantes para a antecipação da colheita de sementes é uma prática comum em diversas culturas como feijão (Goffnett et al, 2016), soja (Bezerra et al, 2016, trigo (Krenchinski et al, 2017), arroz (He et al, 2015), canola (Zhang & Van Vekdhuizen, 2016) e mamona (Costa et al, 2018). Para a maioria das culturas há dessecantes registrados, porém, na cultura do sorgo a dessecação, quando necessária, é feita de forma empírica pelos produtores e não há produtos registrados.…”