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The testing result in two years showed that the effect of typicalness in corn and sorghum hybrids on yield was significant. Within the definite rang of seed grade, when the untypical plants increase one percent, the yield would decrease by 16.1kg/mu in corn and by 12.1kg/mu in sorghum. The main factor with which the untypical plant effect the yield was the difference among the type of untypical plants. In general, the individual productivity of the untypical plants was lower than that of the typical plants in... The testing result in two years showed that the effect of typicalness in corn and sorghum hybrids on yield was significant. Within the definite rang of seed grade, when the untypical plants increase one percent, the yield would decrease by 16.1kg/mu in corn and by 12.1kg/mu in sorghum. The main factor with which the untypical plant effect the yield was the difference among the type of untypical plants. In general, the individual productivity of the untypical plants was lower than that of the typical plants in hybrid. The average results in two years showed that the single ear weight of the untypical plant in corn was less than that of typical plant by 62.7%, while in sorghum by 60.9%. But according to the percent of untypical plants the estimated decrease of yiel was much less than the actual decrease. The fact is caused by "potential untypical plants" which are very difficult to identify in external appearnce. These potential untypical plants resulted in the decrease of individual productivity of typical plant since decreasing typicalness in hybrid. Thus, the generations of stock reproducing should be limited, the inpurity prevented and the typicalness maintained in hybrid seed production. The testing result showed that the current seed grading standard inour country is probable reasonable. The difference of price betweenseed grade should be increased properly, so as to promote the production of higher typicalness in hybrid seed. 两年的试验结果表明,玉米、高粱杂交种种子纯度对其产量的影响是显著的。在规定的种子等级范围内,杂株率每增加1%,玉米减产32.3斤/亩。高粱减产24.3斤/亩。杂株类型的不同是杂株率影响产量高低的主要因素。一般杂株的单株生产力均明显低于杂交种典型株。两年的平均结果指出,玉米杂株比典型株单穗重低62.7%。高粱杂株比典型株单株低60.9%。但是,按杂交株率折算减产的数量显著低于实际减产的数量。这主要是由于一些外形上无法识别的“潜在杂株”造成的。杂交种典型株的单株生产力也随着纯度的下降而减产。因此,在杂交种种子生产中要减少亲本的繁殖世代,搞好防杂保纯工作。试验结果表明,我国现行的种子分级标准基本上是合理的,种子价格的级差应该适当增加,以促进更高纯度杂交种种子的生产。 The esterase isoenzyme of the hybrids between rice and sorghumhave been analysed,the zymogram of the esterase isoenzyme in hybridsare essentially the same as those of the female plant(the japanese type).But a No.Ⅱ band in embryo,anther and other organs of hybrids whichdid not appear in maternal plant was found in sorghum.The segregati-ons of this band could be seen is each generations,but appeared mostfrequently in F_2-F_3,decreased in F_4 and steadied on higher generations.There are seven types of segregations... The esterase isoenzyme of the hybrids between rice and sorghumhave been analysed,the zymogram of the esterase isoenzyme in hybridsare essentially the same as those of the female plant(the japanese type).But a No.Ⅱ band in embryo,anther and other organs of hybrids whichdid not appear in maternal plant was found in sorghum.The segregati-ons of this band could be seen is each generations,but appeared mostfrequently in F_2-F_3,decreased in F_4 and steadied on higher generations.There are seven types of segregations found in F_2~F_5.Experimental re-sults show that the hybrids can obtain from sorghum the genetic materi-al,which results in the phenotype variation of the progenies on molec-ular level;this indicares that the heterogenetic DNA obtained by thehybrid undergo a gradual process of exclusion,segregation and final sta-bilization in their progenies.The No.Ⅱ band appears again in the succ-eeding generations of the plants which have lost this band,it also indi-cates that the phenotype variation is taken place because of the control-ling of gene expression,not because of the structure gene. 分析水稻与高粱杂交后代酯酶同工酶,其酶谱基础与母本粳稻相同,但子代中的种胚、花药等器官出现一条与高粱位置相同而母本水稻没有的第Ⅱ酶带。同时,系统分析了 F_2~F_3及高世代,揭示了这条酶带的遗传现象:杂种各世代多数株系和单株具有这条酶带,并出现分离,绝大多数发生在 F_2~F_3,F_4以后减轻,至高代不再分离;在 F_2~F_5连续世代中,第Ⅱ酶带的出现有七类不同情况。实验结果表明:杂种获得了高粱的遗传物质,导致分子水平的表型变异;异源DNA 在子代中有被排斥、分离、最后稳定的过程;从缺失第Ⅱ酶带的植株后代中又有这条酶带出现,亦可看出表型变异不在于结构基因,而是基因表达调控的结果。 Due to the great genetic difference between local early maturing sorghum and exotie materiac, it is very difficult to obtain a satisfactory breeding parent from a single cross between above two kinds of genetic rosouces in the early maturing sorghum production area of north china. The problem can be solved by using the successive crossing method. In this way, it is possible to select parents material with satisfactory agronomic characters for planting in the northern part of china. In improving tropical genetic... Due to the great genetic difference between local early maturing sorghum and exotie materiac, it is very difficult to obtain a satisfactory breeding parent from a single cross between above two kinds of genetic rosouces in the early maturing sorghum production area of north china. The problem can be solved by using the successive crossing method. In this way, it is possible to select parents material with satisfactory agronomic characters for planting in the northern part of china. In improving tropical genetic resources and making hybridic crosses, seed presenility is one of the problems often encountered. In general, the problems is related to the relationship between the parents used. The hybrids are normal if the relationships are close or the parents of a given cross are not presenile. The hybrids may be seriesly presenile if one of the parents is presenile. The maturing dates of those hybrids with some exotic pedigree are usualy significantly celayed when they are planted in cold arer, it is definntly recessary to develop varieties or hybrids which is insensitive to temperature in the northern early maturing sorghum production area of china. 在中国早熟高粱栽培区,直接利用热带种质资源与中国高粱杂交,由于类型间的差异过大,不易选出优良的亲本。用递交法可以克服这一不足,可从杂交后代群体中选出农艺性状较好且适于北方种植的优良亲本。在改良热带种质资源和选配杂交组合时,子粒早衰与亲本间的亲缘有关。双亲亲缘关系远或两亲之一早衰的,杂种F_1往往早衰严重。有国外亲缘的杂交种,在气温低的地区种植,生育期明显地延迟。在中国北方早熟高粱区,需选育对温度反应不敏感的高产、稳产的高粱品种或杂交种。
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