Contradictory results of the paclobutrazol (PAC) effect on maize plants were obtained under semiarid compared to well-watered conditions with grain yield improvements versus depressions, respectively. In addition, maize cultivars differed in their reactions to similar PAC dosages. Thus, in the present study PAC was applied in the appropriate dosage at growth stage V5 to six maize cultivars (Zea mays L. cvs. Amanova, Severeen, Hubble, Galactus, Fabregas, Pioneer 3906) grown in a container experiment under well-watered conditions. PAC caused significant decreases in plant height, increases in culm diameter and reduced transpiration rates in comparison with the untreated control plants. At anthesis, start and duration of pollen production, start of silking and anthesis-silking interval (ASI) were mostly unaffected by PAC application. Senescence of PAC-treated plants was delayed by one week. Apart from cultivar Galactus, PAC treatment caused significant grain yield reductions between 9% and 20%, which were solely based on decreases in kernel number because higher single kernel weights were obtained. In all cultivars, reductions in straw yield of 28% to 49% were achieved with PAC application, which were responsible for significant improvements of the harvest index by 8%–36%. PAC-treated plants showed reduced water consumption (11%–21%), resulting in significantly improved WUE_grain during the critical period of kernel setting of the cultivars Amanova, Severeen, Galactus and Fabregas. The results indicate that PAC treatment of maize plants bears several advantages such as reduced water demand and improved water-use efficiency (WUE), higher mechanical strength of the stalk and an enhanced harvest index. Possible grain yield decreases per plant under well-watered conditions could be counteracted by moderate increases in plant density, yet concurrently this might diminish some of the beneficial PAC effects.

中文翻译：

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植物生长调节剂多效唑可提高玉米的水分利用效率

与半干旱条件下相比，多效唑对土壤中玉米植物的影响与多效唑的结果相反，谷物产量分别相对于低谷有所改善。此外，玉米品种对相似PAC剂量的反应也不同。因此，在本研究中，将PAC以合适的剂量在第V5生育期施用于6个玉米品种（玉米L. cvs。Amanova，Severeen，Hubble，Galactus，Fabregas，Pioneer 3906）在容器实验中在充足的水条件下生长。与未处理的对照植物相比，PAC引起植物高度的显着降低，茎秆直径的增加和蒸腾速率的降低。在花期，花粉生产的开始和时间，花期的开始和花期的间隔时间（ASI）基本上不受PAC的影响。PAC处理过的植物的衰老被推迟了一个星期。除半乳糖外，PAC处理还导致谷物产量显着下降9％至20％，这完全基于籽粒数量的减少，因为获得了更高的单粒重量。在所有品种中，使用PAC可使秸秆产量降低28％至49％，这使收获指数显着提高了8％–36％。PAC处理过的植物显示出减少的耗水量（11％–21％），从而显着改善了WUE_谷物在品种Amanova，Severeen，吞噬者和法布雷加斯的内核设置的关键时期。结果表明，PAC处理玉米植物具有几个优点，例如减少了需水量和提高了用水效率（WUE），提高了秸秆的机械强度并提高了收获指数。适度增加植物密度可以抵消在水分充足条件下每株植物可能降低的谷物产量，但是同时这可能会减少一些有益的PAC效应。