Flowering Synchronization in Hybrid Rice Parental Lines at Different Sowing Dates

Abstract

Hybrid seed set on the female line depends primarily on its flowering synchronization with the restorer line (R), therefore, the sowing of male and female lines must be planned properly to achieve this. Field experiments on different sowing dates (May 1st, May 15th, and May 30th) of R lines (Giza 178R, Giza 179R, and Giza 181R) and cytoplasmic male sterile (CMS) lines (IR69625A, IR70368A, IR58025A, K17A, and G46A) were carried out at the farm of Sakha Agricultural Research Station, Kafr El-Sheikh, Egypt during 2019 and 2020 to study the effect of sowing dates on flowering synchronization in hybrid rice. The results indicated that the synchronization of flowering between CMS lines and R lines has highly significant effects on the days to 50% heading, number of leaves, effective accumulated temperature (EAT), plant height, panicle exertion percentage, panicle length, number of fertile panicles, panicle weight, seed set percentage, harvest index and seed yield of hybrid rice. The highest seed yield (1.72 and 1.41 t ha−1, respectively in 2019 and 2020) was recorded from the sowing date May 1st and the hybrid combination of Giza 178R × IR58025A (2.06 and 2.12 t ha−1 in 2019 and 2020, respectively). The grain yield had a significant and highly significant positive correlation with the plant height (cm), panicle exertion percentage, panicle length, number of panicles plant−1, panicle weight, seed set percentage, and harvest index. In Egypt, May 1st is the best time for the synchronization of hybrid rice lines and a combination of Giza 178R × IR58025A may be recommended for better performance.

Heterosis and combining ability for floral and yield characters in rice using cytoplasmic male sterility system

“…These characteristics are easier in selection compared with grain yield, which is advantageous in breeding programs. These results are in consonance with the findings of Sheehy et al, 2001 , Li et al, 2019 , Oladosu et al, 2018 , Zhao et al, 2020 , and Gaballah et al (2021) .…”

Genome-wide association study reveals novel genomic regions governing agronomic and grain quality traits and superior allelic combinations for Basmati rice improvement

“…The traits investigated in the present study were crucial for the breeding programs aiming for the development of parental lines for hybrid development and improvement of grain quality in Basmati rice. Synchronization of flowering is one of an important consideration which determines better nicking of parents during hybrid seed production ( Gaballah et al., 2021 ). The MTA, qDFF6.1 was detected as the most reliable QTN for DFF, since its presence was evident in most of the locations and lies within the RFT1 gene ( Os06g0157500 ), which is directly involved in controlling flowering time in rice ( Komiya et al., 2009 ).…”

Hybrid Rice Production: A Worldwide Review of Floral Traits and Breeding Technology, with Special Emphasis on China

“…Another important consideration is flowering synchronization since improper synchronization might result in the absence of, or a poor, seed set. In addition, the impact of other environmental factors, such as a shortage of water and its impact on floral traits, should be taken into consideration during the production of seeds [ 34 , 35 , 36 , 37 , 38 ]. However, the improvement of floral traits is challenging due to their complex genetic regulation and interactions with environmental factors [ 39 ].…”

“…To produce pale blue flowers, the CRISPR/Cas9 system has been successfully applied to alter the color of flowers in Torenia fournieri [ 206 ], as well as multiplex CRISPR-Cas9, which introduce novel flowering and architectural characteristics in hexaploid Camelina sativa [ 207 ]. For instance, adjusting the flowering period can assist in synchronizing the female and male parental lines’ flowering, which is important to increase hybrid rice production [ 37 ]. Researchers often identify the genes responsible for the qualities they want to modify before using gene editing to change floral attributes in hybrid rice [ 60 ].…”