外源ABA和水分胁迫对不同基因型三叶草生长的影响

在室内研究了不同浓度外源ABA处理和不同水分胁迫对 6种不同基因型的三叶草 (TrifoliumsubterraneumL .)生长的影响。当三叶草的第四片叶完全展开时 ,向营养液中施加不同浓度的ABA时对盆栽土壤进行控水。在处理的 1,4 ,7和 11d ,测定植株鲜重、叶片数、最长根长 ,以表示三叶草的生长状况。各参试品种以上三项生长指标均受外源ABA和水分胁迫的影响而呈现下降的趋势。同时 ,叶片水势值随ABA浓度的增加和水分胁迫强度的增加而明显降低。在 10 -4mol/LABA处理 11d后 ,参试品种平均生长量的减少与水分胁迫 15d后其生长量的减少的结论一致。在不同浓度ABA处理下 ,不同基因型三叶草平均叶片数 ,完全展开叶面积和每株干物质重约降低了5 0 % ,而其根冠比却增加了 80 %。不同基因型三叶草生长参数间的变化及排序结果与盆栽相同品种获得的实验结果非常相似。品种Clare、Nuba和SeatonPark在对照和处理下均表现最好。由于三叶草对一定浓度范围的外源ABA的反应与其在盆栽水分胁迫下的反应结果十分相似 ,因此 ,利用外源ABA处理的方法来研究不同基因型三叶草的耐旱性将可能是一种行之有效的方法。

Effects of Exogenous Abscisic Acid and Water Stress on the Growth Response of Subterranean Clover of Different Genotypes

The response of subterranean clover ( Trifolium subterraneum L.) to different abscisic acid (ABA) concentrations (10 -6 , 10 -5 , 10 -4 mol/L) in nutrient solution and to water stress were studied in growth room. Six cultivars of contrasting yield capacity were compared. Plants remained growing in Hoagland solution or pots until at least four full_developed leaves appeared. The ABA was then applied and the fresh weight, leaf number and length of the largest root were measured at 1, 4, 7 and 11 d after ABA treatment. The above parameters were also measured at 15 d under water stress. In all the tested genotypes ABA caused similar reduction in these growth parameters, as well as a significant decrease of leaf water potential which was dependent on ABA concentration. The average growth reduction after 11 d under 10 -4 mol/L ABA coincided with the range of these crops under water stress in pot experiments. On average of the different genotypes, leaf number, area of full_developed leaf and the dry weight per plant decreased by about 50% whereas the root/shoot ratio increased by 80%.The genotype variation and ranking for this treatment were rather similar to the same genotypes in pot experiments. The genotypes, Clare, Nuba and Seaton Park, showed the best results under both control and ABA treated conditions and water stress conditions. The similarity between the response to ABA in nutrient solution and to water stress opens the possibility to use this approach as a way to quantify the drought resistance of subterranean clover genotypes.