为探究不同生育阶段受旱情形对夏玉米生长发育和产量形成的影响, 2013和2014年在陕西杨凌进行了遮雨棚下夏玉米田间控水试验,试验设置了70和110 mm两个灌溉水平(I1和I2),每个灌溉水平下依次设置了夏玉米苗期干旱(D1)、拔节期干旱(D2)、抽雄期干旱(D3)和灌浆期干旱(D4)等4种受旱情形,由此共形成8个处理,每个处理3个重复,按裂区试验进行田间布置,同时还设置一个全生育期均灌水的对照处理,据此分析了不同生育时期受旱条件下夏玉米的株高、叶面积、生物量和产量等生理生态指标的变化特征,以及整个生育期蒸散量和水分利用效率的变化规律。结果表明：在营养生长前期(拔节前)受旱,一方面会严重影响夏玉米的生长发育,其株高、叶面积、地上部生物量均明显偏低；另一方面也会影响产量的形成,导致果穗发育不全,果穗长和直径偏小,秃尖长度偏大。营养生长阶段受旱还能推迟夏玉米物候期,如在苗期或者拔节期受旱最长可使夏玉米推迟6 d进入抽雄开花期；而生殖生长阶段受旱则能使夏玉米生育期缩短,如在抽雄期或灌浆期受旱能使夏玉米提前2 d左右成熟。夏玉米果穗籽粒行数对水分胁迫不敏感,受旱时段及灌水水平都对其没有显著影响。不同的灌水水平与受旱时段对夏玉米的产量有明显的交互作用,拔节前受旱会使最终产量偏低,且低灌水处理产量低于高灌水处理；在抽雄期受旱会明显减少穗粒数,但在同一灌水水平下产量是最高的；灌浆期受旱不仅明显减小了百粒重导致减产,而且蒸散量偏大,导致水分利用效率降低。因此,灌水水平较低时,应尽量避免玉米营养生长阶段(出苗和拔节)受旱,以避免大幅减产；灌水水平较高时,可选择在苗期适度亏水,并避免灌浆期受旱,以保证高产。
英文摘要:
A water control experiment was carried out under rainout shelter in the growth seasons of 2013 and 2014 to investigate the influences of water stresses imposed at different development stages on development and grain yields of summer maize in Yanling, Shaanxi Province. The dynamic changes of several eco-physiological indicators of maize growth were measured and analyzed, including height, leaf area index (LAI), biomass, and grain yield. The variation of evapotranspiration and water use efficiency of summer maize were also measured and analyzed . The whole growth season of summer maize was divided into four stages: seeding, jointing, tasseling, and grain filling. Irrigations were applied on three stages while keeping one stage dry, i.e. four scenarios of water stress (D1-D4) were designed during each growth season. There were two irrigation levels (I1=70 mm, I2 =110 mm). Thus, there were a total of eight treatments that had three replicates and followed a split-plot experiment design. An extra treatment with irrigations at all four stages was arranged nearby. The results showed that water stress at early vegetative stage (before jointing) could seriously affect the growth of summer maize since plant height, LAI, aboveground biomass were all remarkably lower than other treatments. It also could seriously affect the grain yields of summer maize since ear length and diameter were lower and bald length was longer. Water stress at early vegetative stage (before jointing) could extend the growing season of summer maize. The maximum delay of tasseling date could be six days when water stress occurred at seeding or jointing stage. Water stress at reproductive stage (after tasseling) could shorten the growing season of summer maize. Water stress at tasseling or grain filling stage could advance maturation date by two days. In addition, different irrigation levels could also influence the length of growing season of summer maize. The number of kernel rows of summer maize was not sensitive to water stress since drought periods and irrigation levels had no significant influence on it. Different irrigation levels and water stress stages had strong interactions on grain yield of summer maize. Grain yield was relatively low when there was water stress before jointing. Water stress at tasseling remarkably reduced grain number per ear, but the grain yield was the highest among the treatments with the same irrigation level. Water stress at grain filling stage not only obviously reduced hundred-kernel weight and grain yield, but also decreased water use efficiency of summer maize since much water was wasted. In general, water stress should be avoided at the vegetative growth stages (seedling and jointing) when under a lower irrigation level to prevent large loss of grain yield. However, when under a higher irrigation level, limited irrigation could be applied at the seedling stage but water stress should be avoided at the grain filling stage to guarantee a higher yield.
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