Morphological and physiological properties of hybrid rice seeds with top-gray chalkiness

Metagenomic Sequencing to Analyze Composition and Function of Top-Gray Chalky Grain Microorganisms from Hybrid Rice Seeds

“…Then, the seeds were selected by a YH-101 automatic optical seed chalky rate detector (Hunan Shanzhen Technology Co., Ltd., Changsha, China). The normal seeds and chalky seeds were clarified according to Zhang et al [ 6 ] and Chen et al [ 8 ]. Briefly, the normal seeds were the same seeds selected without chalkiness, and the chalky seeds were mixed from grade 1 to grade 3 using the detector.…”

“…The effective germination was confirmed by the following standard: when the length of the radicle equaled that of the seed, the length of the germ was over one-half of the length of the seed [ 37 ]. The determination of seed germination indexes, including the germination potential (GP), the germination rate (GR), the simplified vigor index (VI), and the shoot height, was conducted according to Chen et al and Zhao et al [ 8 , 38 ]. GP was investigated on the third day after transplantation (d.a.t.…”

“…In recent years, high temperature and humidity have become negative issues, impacting hybrid rice breeding in this area. We previously observed that hybrid rice seeds exhibited quite a high proportion of top-gray chalkiness, in which the chalky part originated from the upper part of the grain opposite to the embryo other than the five types of chalkiness reported by Yoshioka et al, and it was noticed that the chalkiness rate of seeds was closely related to the glume dehiscence rate, where the higher the ambient temperature and humidity were, the higher the chalkiness rate emerged [ 8 , 9 ]. This phenomenon has been seriously troubling the processing of hybrid rice seeds.…”

“…Our previous research showed that the starch granules of the chalky parts of hybrid seeds collapsed and were infected, which could infect normal seeds during seed storage, processing, and soaking periods, and seed coating agents containing fungicides or bactericides could suppress this phenomenon to an extent [ 8 , 12 ]. The seed-associated microorganisms are quite complicated, and there are still few papers on the transmission and infection mechanism of top-gray chalkiness in hybrid rice seeds [ 13 ].…”