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首页> 外文学位 >Evaluation of a mechanistic mathematical model to predict nutrient uptake by field-grown paddy rice and selection of a chemical extractant to assess phosphorous availability in rice soils.
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Evaluation of a mechanistic mathematical model to predict nutrient uptake by field-grown paddy rice and selection of a chemical extractant to assess phosphorous availability in rice soils.

机译：评估预测田间种植的水稻吸收养分的机械数学模型，并选择化学提取剂以评估稻田土壤中的磷有效性。

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Three rice (Oryza sativa L.) cultivars were grown on a Crowley silt loam at the Rice Research and Extension Center to evaluate the ability of a mechanistic model to predict NH{dollar}sb4sp+,{dollar} P and K uptake. Total nutrient uptake and root and soil parameters were measured on soil samples representing 5 cm depth increments down to 40 cm during vegetative and reproductive growth. The soil and plant parameters were input into the Barber-Cushman model to predict nutrient uptake. The model accurately predicted nutrient uptake during vegetative growth but underpredicted uptake during reproductive growth. It is postulated that rapid root senescence during reproductive growth prevented accurate estimation of root length developed during this stage of growth and resulted in the underprediction. Approximately 90% of the total NH{dollar}sb4sp+,{dollar} P and K uptake by rice occurred within the surface 20 cm of soil. Ammonium and P uptake in the 0- to 20-cm of the soil depth were most sensitive to half-distance between root axes, root radius, nutrient solution concentration and buffer power. Potassium uptake was most sensitive to maximum influx rate, root radius, Michaelis constant and root growth rate throughout the soil profile.; The Mehlich-3 extractant, used by soil testing, is not consistent in predicting rice response to P fertilization on three soils (Crowley silt loam from Arkansas county and a Hillemann silt loam from Poinsett and Cross counties). A greenhouse study was conducted to evaluate the effect of P fertilizer on plant growth parameters and to identify a suitable chemical extractant to assess P availability in flooded rice soils. Rice was grown on these soils with fertilizer rates of 0, 5, 10, 20 and 40 mg P kg{dollar}sp{lcub}-1{rcub}.{dollar} Shoot and root measurements were taken at three sampling dates (37, 44 and 137 days after emergence (DAE)). Phosphorus fractionation and P extracted by Mehlich-3, Bray-1, Olsen and anion exchange resin (resin) were conducted on these sampling dates and also at 0 days after flooding (DAF). At 137 DAE, kernel weight and total P uptake by rice grown on the three soils were maximized at 10 mg P kg{dollar}sp{lcub}-1{rcub}.{dollar} Phosphorus fertilizer applied to the three soils stimulated organic P mineralization and increased the nonoccluded and solution P fractions. Nonoccluded P and solution P fractions were significantly correlated to most plant growth parameters measured. Extractable P measured by resin at 0 DAF was consistently correlated to total P uptake measured at 24, 31 and 124 DAF. The Barber-Cushman model indicated that the resin method is suitable to assess available P in these soils. The resin, with its high exchange capacity compared to soil, removes the most available P in soil.
机译：在水稻研究与推广中心的克劳利粉壤土上种植了三个水稻（Oryza sativa L.）品种，以评估机理模型预测NH {dol} sb4sp +，{dol} P和K吸收的能力。在营养生长和生殖生长过程中，对土壤样品进行了总养分吸收以及根部和土壤参数的测量，这些样品代表从5厘米深度增加到40厘米深度。将土壤和植物参数输入到Barber-Cushman模型中以预测养分吸收。该模型可以准确预测营养生长过程中的养分吸收，但会预测生殖生长过程中的养分吸收。据推测，生殖生长过程中快速的根部衰老妨碍了在生长的这一阶段对根长的准确估计，从而导致预测不足。水稻吸收的NH {sb4sp +，{dolal} P和K总量中，约90％发生在20 cm的土壤表层。在土壤深度的0至20厘米内，铵和磷的吸收对根轴，根半径，营养液浓度和缓冲能力之间的半距离最为敏感。钾的吸收对整个土壤剖面中的最大流入速率，根半径，米氏常数和根生长速率最敏感。用于土壤测试的Mehlich-3提取剂无法预测水稻对三种土壤（来自阿肯色州的Crowley淤泥壤土和来自Poinsett和Cross县的Hillemann淤泥壤土）对磷肥的反应。进行了温室研究，以评估磷肥对植物生长参数的影响，并确定合适的化学提取剂以评估水稻田中磷的有效性。在这些土壤上种植水稻，肥料用量为0、5、10、20和40 mg P kg {dol} sp {lcub} -1 {rcub}。{dollar}在三个采样日期进行了茎和根的测量（37 ，出现后44天和137天（DAE）。在这些采样日期以及水淹后0天（DAF）分别进行磷分级和通过Mehlich-3，Bray-1，Olsen和阴离子交换树脂（树脂）提取的P。在137 DAE时，在这三种土壤上种植的水稻的粒重和总P吸收最大，为10 mg P kg {dol} sp {lcub} -1 {rcub}。{dollar}在这三种土壤上施用的磷肥刺激了有机P矿化和增加非封闭和溶液P分数。 Nonoccluded P和solution P分数与大多数测得的植物生长参数显着相关。树脂在0 DAF下测得的可提取P与在24、31和124 DAF下测得的总P吸收始终相关。 Barber-Cushman模型表明，树脂法适合评估这些土壤中的有效磷。与土壤相比，该树脂具有高交换容量，可去除土壤中最有效的磷。

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