| A lot of practice and research showed that pre-harvest sprouting in rice is very serious at recent years in China.The percent of pre-harvest sprouting in rice is about 5%in normal years.If mature stage confronts the cloudy and rainy weather,the percent of pre-harvest sprouting would reach 10%,even reach 90%.The sterile lines which easily leaded to pre-harvest sprouting includeâ…¡-32A,Zhenshan 97A,G46A,Jin 23A,BoA,Xinxiang A,V20A,Xie A and so on.The combinations which come from those sterile lines account for above 85%in all areas of the hybrid rice.Therefore the pre-harvest sprouting in rice lead to large loss of economic returns and the largest harm to the normal seed is the extract from sprouting seed inhibits the normal seed from germinating.Quadratic orthogonal regressive rotation design of three factors is applied to study the effect of inhibitor A,inhibitor B,inhibitor C on seed germination in the paper.The aim is to select an effective inhibitor combination to inhibit pre-harvest sprouting in rice and it no harm to the quality of seed.Beside,the electrophoresis of Amylase isozyme for analyzing the inhibitor combination to inhibit seed from germinating and the assaying of hormone are conducted in the paper.The results were as follows:1.Quadratic orthogonal regressive rotation design of three factors is applied to select an effective inhibitor combination to inhibit pre-harvest sprouting in rice.The results showed that the effect of inhibitor combination on seed germination were in the order of inhibitor A,inhibitor C and inhibitor B.The best combination was as following:A 9.54mg/L+ B 95.46mg/L+ C 1104.54mg/L.In theory,the percent of ingeminated seeds is 62%after the treatment with inhibitor combination,which is highly more than CK.The bands of Amylase isozyme of seed of G46A and D62A which sprayed GA are same as CK after the treatment with inhibitor combination on yellow mature stage and full mature stage,Whereas the inhibitor combination were effective to inhibit seed which spayed GA from germinating.The bands of Amylase in geminated seed are not inhibited after the treatment with inhibitor combination.2.The effect of inhibitor combination inhibiting pre-harvest sprouting in rice was as follows:(1) there is different inhibited effect of pre-harvest sprouting in rice after the treatment with different dosage of inhibitor combination.The inhibited effect raise up gradually as the dosage rises up.The difference between every treatment and CK is significant and the difference between every treatment is not significant.The percent of pre-harvest sprouting in rice is 64.5%by spraying water.But it reduced to 53.5%,51.5%and 50.1%respectively after the treatment with different dosage of inhibitor combination.(2)The effects of inhibitor combination on pre-harvest sprouting in rice were in the order of D62A,â…¡-32A,G46A.The percent of pre-harvest sprouting in rice reduced to17.8%,16.5%and 13%respectively after the treatment with inhibitor combination.(3)There were good inhibited effects after the treatment with inhibitor combination on yellow mature stage and full mature stage. But the inhibited effects were different after the treatment with inhibitor combination on different stage.The best was yellow mature stage.The last was full mature stage. (4) The percent of the geminated seeds rose up gradually in 1 to 3 months,and is the same as CK after 3 months.3.The assaying of hormone in every period of G46A and R527.The results were as follows:(1) The GA and ABA content in every period of G46A which easily leaded to pre-harvest sprouting were all more than that of R527,which showed that the rice which easily leaded to pre-harvest sprouting easily induced synthesis of hormone on same condition and the endogenous ABA and GA content would be an important factor of seed germination.(2) On yellow mature stage and full mature stage,the seed has finished its development and has the capability of geminating,the ABA content on yellow mature stage is no little than that of full mature stage,but the percent of geminated seeds on yellow mature stage is highly lower than that of full mature stage on same condition.In the same,the ABA content in the rice which easily leaded to pre-harvest sprouting is more than that of R527 on same stage,but the percent of geminated seed of G46A is highly more than that of R527 on the same condition.This showed that whether the seed germinate or not is not completely depend on the ABA content and the sensitivity to hormone of the embryo is also an important factor.The experiment showed that the embryo of seed of G46A which easily leaded to pre-harvest sprouting is more sensitive to hormone in every stage than that of R527 and the more developed the more sensitive as they developed.This would be the physiological mechanism that leaded to easily pre-harvest sprouting in the hybrid rice.(3) On every stage,the ABA and GA content of G46A and R527 are both little than that of CK after the treatment with inhibitor combination.This showed that the inhibitor combination inhibited the synthesis of hormone effectively.The percent of the geminated seeds rose up gradually in 1 to 3 months,and is the same as CK after 3 months.This showed that the inhibitor combination has no harm to the embryo,but temporarily decrease the embryo sensitivity to hormone.This would be the physiological mechanism of the inhibitor combination which inhibits seed from germinating.
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