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新西兰奥克兰essay代写:大豆营养期

大豆营养期干旱胁迫的影响主要表现在植株和根系的大小上。干旱胁迫下的大豆植株由于缺水、养分有效利用和养分吸收等原因,叶片较小,植株较短(爱荷华州立大学,2017)。“与我在《玉米相关效应》中所描述的类似,在这一阶段,由于施肥的深度较浅,无法被根系吸收以弥补营养的缺乏,根系也经常受到影响。在这段时间里,大豆根系的生长实际上是增加的,因为植物在寻找营养来继续生长。由于根系生长的增加,植物碳水化合物被转移到根系以促进生长,而不是储存或植物生长(爱荷华州立大学,2017)。早期生殖阶段(R1-R5)对胁迫最敏感,最终影响强度和作物生长速率(Pederson, 1945)。Pederson说:“R4-R5是对水分胁迫最敏感的(Pederson, 1945)。“虽然这个阶段是最敏感的,但它对根的生长没有影响。Hoogenboom和他的团队指出:“在植株达到合果发育阶段(R4)后,根的生长受干旱的影响较小,最终在种子灌入阶段停止(R5) (Hoogenboom等,1987年)。“在严重的干旱胁迫下,为了在早逝前产生种子,大豆可能会提前开花(爱荷华州立大学,2017)。”“这是植物保持生存和成功的策略,但产量仍将大幅下降.

新西兰奥克兰essay代写:大豆营养期

Effects of drought-related stress during the vegetative stage in soybeans is often exhibited in the size of the plant and of its root system. “Drought stressed soybean plants are often shorter with smaller leaves due to lack of water, nutrient availability, and nutrient uptake (Iowa State University, 2017).” Similar to what I described in the corn-related effects, the root system is often affected during this stage due to the fact that fertilizer is put in a shallower depths and is out of root reach for uptake to compensate for the lack of nutrients. Soybean root growth actually increases during this time, because the plant is searching for nutrients to continue its growth. Due to this increase in root growth, the plants carbohydrates are shifted to the roots to fuel the growth rather than for storage or plant growth (Iowa State University, 2017). The early reproductive stages (R1-R5) are most sensitive to stress, which will ultimately effect strength and crop growth rate (Pederson, 1945). Pederson states that “R4-R5 is the most sensitive to moisture stress (Pederson, 1945).” While this stage is the most sensitive it does not have an effect on root growth. Hoogenboom and team state that “root growth was less affected by drought after the plants had reached he pod development stage (R4) and finally ceased during seed fill (R5) (Hoogenboom, et al., 1987).” “Under severe drought stress, soybean flowering may occur earlier than normal in an effort to produce seed before premature death (Iowa State University, 2017).” This is the plants strategy to remain viable and still be successful, but the yields will still be quite diminished.

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