Studies on optimum harvest time for hybrid rice seed.
BACKGROUND
Timely harvest is critical for hybrid rice to achieve maximum seed viability, vigor and yield. However, how to predict the optimum harvest time has been rarely reported so far.


RESULTS
The seed vigor of Zhuliangyou 06 (ZLY06) increased and reached the highest level at 20 days after pollination (DAP), when seed moisture content had a lower value, which was maintained until final seed maturation. For Chunyou 84 (CY84), seed vigor, fresh and dry weight had relatively high values at 25 DAP, when seed moisture content reached the lowest value and changed slightly from 25 to 55 DAP. In both hybrid rice varieties, seed glume chlorophyll content declined rapidly from 10 to 30 DAP and remained at a very low level after 35 DAP. Starch content exhibited an increasing trend during seed maturation, while both soluble sugar content and amylase activity decreased significantly at the early stages of seed development. Moreover, correlation analyses showed that seed dry weight, starch content and superoxide dismutase activity were significantly positively correlated with seed vigor. In contrast, chlorophyll content, moisture content, soluble sugar, soluble protein, abscisic acid, gibberellin content, electrical conductivity, catalase and ascorbate peroxidase activities were significantly negatively correlated with seed vigor. Physiological and biochemical parameters were obviously more closely related with seed vigor than with seed germinability during seed development.


CONCLUSIONS
Seed vigor could be better used as a comprehensive factor to predict the optimum seed harvest time. It is suggested that for ZLY06 seeds could be harvested as early as 20 DAP, whereas for CY84 the earliest optimum harvest time was 25 DAP. © 2016 Society of Chemical Industry.
Seed Science Center, Department of Agronomy, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China.
Hong
H
Fu
Zhejiang Nongke Seed Industry Co., Ltd., Hangzhou 310021, China.
Dong-Dong
DD
Cao
Seed Science Center, Department of Agronomy, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China.
Wei-Min
WM
Hu
Seed Science Center, Department of Agronomy, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China.
Ya-Jing
YJ
Guan
Seed Science Center, Department of Agronomy, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China.
Yu-Ying
YY
Fu
College of Agronomy, Gansu Agricultural University, Lanzhou 730070, China.
Yong-Feng
YF
Fang
Seed Science Center, Department of Agronomy, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China.
Jin
J
Hu
D000040:Abscisic Acid / Q000378:metabolism; D000383:Agriculture / Q000379:methods*; D018533:Biomass; D050260:Carbohydrate Metabolism; D002374:Catalase / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D056084:Genetic Fitness; D018525:Germination; D005875:Gibberellins / Q000378:metabolism; D006801:Humans; D006823:Hybrid Vigor; D006824:Hybridization, Genetic; D012275:Oryza / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D000069600:Plant Breeding; D010940:Plant Proteins / Q000378:metabolism; D012639:Seeds / Q000254:growth & development* / Q000378:metabolism; D013213:Starch / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism
D005875:Gibberellins; D010940:Plant Proteins; D002734:Chlorophyll; D000040:Abscisic Acid; D013213:Starch; D002374:Catalase; D013482:Superoxide Dismutase
hybrid rice seed; morphological and physiological changes; optimum harvest time; seed vigor