Study on susceptibility of different maize genotypes to zinc deficiency

صينى. 采用砂培试验方法，在缺锌条件下对35个玉米基因型的缺锌敏感性及相关影响因子进行了比较和评价。根据培养试验中玉米幼苗叶片缺锌症状出现的严重程度和时间早晚,将供试玉米基因型划分为缺锌敏感型、中等敏感型和非敏感型3种类型。对10个缺锌敏感型和非敏感型玉米基因型进行比较发现，外界缺锌对玉米幼苗期的生物量影响不大，敏感型玉米基因型仅仅从外观上显示出缺锌症状。缺锌能显著降低缺锌敏感型玉米基因型叶片的叶绿素含量，而对非敏感型玉米基因型的叶绿素含量影响较小。缺锌敏感型玉米基因型的根冠比普遍较大，其根冠比均大于1，而非敏感型玉米基因型的根冠比却等于或小于1。缺锌敏感型玉米基因型种子中P/Zn较高，非敏感型玉米基因型的P/Zn较低。在缺锌条件下，缺锌敏感型玉米基因型锌从种子向地上部转移的转移率更高。总的来看，玉米种子中的P/Zn可以作为判断玉米生长期内缺锌敏感性的一个重要指标，玉米幼苗的根冠比可以作为鉴别缺锌敏感性的另一指标。

إنجليزي. The two sand experiments were carried out successively to assess the susceptibility of thirty five maize genotypes to zinc deficiency and their corresponding factors under the conditions of zinc deficiency. Based on the severity and occurrence time of zinc deficiencys, the tested maize genotypes were classified into three types, namely, susceptible genotypes, medium susceptible genotypes and non-susceptible genotype. In addition, the respective five genotypes for susceptible genotypes and non-susceptible genotypes were carefully studied, which indicated that there was no obvious influence of zinc deficiency in environment on yields of maize seedlings, and zinc deficiency symptoms occurred only on the leaves of susceptible genotypes. Zinc deficiency obviously decreased the chlorophyll content of the leaves for susceptible types to zinc deficiency, whereas the leaf chlorophyll content still maintained higher level for non-susceptible genotypes. The susceptible genotypes to zinc deficiency had higher root shoot ratios with more than 1, however, the root shoot ratios were less than or equal to 1 for non-susceptible genotypes. The P/Zn ratios of seeds for the susceptible genotypes were higher than that of non-susceptible genotypes. What’s more, under the conditions of zinc deficiency, the translocation rates of zinc from seed to shoot were higher for susceptible genotypes to zinc deficiency compared with non-susceptible genotypes. In conclusion, the P/Zn ratio of maize seeds can be regarded as an important index to predict the susceptibility of young seedlings to zinc deficiency, and the root to shoot ratios is also an adequate indicator to evaluate the sensitivity of maize plants to zinc deficiency.