Using Weather Data to Estimate Forage Production of Nilegrass
Other Title
利用氣象資料估測尼羅草之牧草生產
Journal
作物、環境與生物資訊
Journal Volume
2
Journal Issue
3
Pages
245-254
Date Issued
2005-09
Date
2005-09
Author(s)
Abstract
In the previous investigation [Lee et al. (2004)], the aboveground fresh-based forage yield at harvest was found best-fitted to a four-variable linear regression model established from seasonal accumulated values of weather data. In this study, whether forage production during the growing periods may also be estimated by a multivariate regression model from weather data was further investigated. Both fresh and dry weights of the aboveground plant parts and plant height of nilegrass (Acroceras macrum Stapf) were measured from field experiments conducted at Taiwan Livestock Research Institute Experimental Farm (Hsinhua) during eight growing seasons from 2002 to 2004. The meteorological data were collected from on-site weather station to calculate the cumulative values along plant development during growing seasons, including the accumulated values of daily mean air temperature (DMAT), daily precipitation (DP), daily evaporation (DE), daily irradiance (IR), and daily sunshine hours (DSH). These climatic variables were used to correlate with plant height and forage production. Results showed that changes of forage production and plant height were shown linearly corresponding to the cumulative values of DMAT, DP, DE, IR, and DSH. By multiple linear regression analyses, estimations of fresh-based and dry-based forage production may be improved by two-variable linear regression models containing DP and IR, with R2=0.667 (P<0.0001) for fresh-based and R2=0.767 (P<0.0001) for dry-based forage production, respectively. Plant height may be best estimated by a two-variable model (R2=0.808, P<0.0001) containing DP and DE. When validating the models with another set of data from different growing seasons, models gave slight over-predicted values of fresh-based and dry-based forage production and plant height. Results also indicated that forage fresh weight was linearly correlated with plant height (R2=0.702, P<0.0001) and forage dry weight (R2=0.874, P<0.0001). Accordingly, unit forage production of nilegrass can be estimated by plant height at the time of sampling.
本系列研究之前項報告[Lee et al. (2004)]指 出，尼羅草(nilegrass, Acroceras macrum Stapf) 收獲時之鮮草產量可以由四氣象變因構成之直 線複迴歸模式的累積氣象數據加以合理的估測。本研究持續探討在尼羅草各生長季節期間，是否依然可由適當的多氣象變因直線複迴歸模式予以評估牧草生產量。本試驗在2002年至2004年的不同生長季節進行牧草栽培，期間分別 量測植株地上部高度(株高)、鮮重(鮮草產量)及乾重(乾草產量)，同時收集位於臺南縣新化鎮試區之農委會畜產試驗所一級農業氣象測站之氣 象測值。將各生長季節之每日氣象測值累積，即成為探討牧草生產量、株高關係之氣象變因，包括每日日均溫(DMAT)、每日降水量(DP)、每日蒸發量(DE)、每日日射量(IR)及每日日照時數(DSH)等五種。根據試驗結果，發現DMAT、DP、DE、IR 及 DSH 之個別累積測值均與牧草 生產量及株高之間呈現直線相關。再由多變因直 線複迴歸分析結果，顯示對鮮草及乾草生產量之估測，可藉由DP及IR兩變因累積值構成之二變因直線複迴歸模式提高估測準確度，鮮草及乾草的決定係數分別達R2=0.667 (P<0.0001)及R2=0.767 (P<0.0001)。對株高之估測，則可藉由DP及DE兩變因累積值構成之二變因直線複迴歸模式提高估測準確度，決定係數為 R2=0.808 (P<0.0001)。經以另一組生長季節氣象資料驗證模式對其他氣象環境之適用性，發現預測值均略為高於實測值。試驗結果又顯示，鮮草生產量與乾草生產量及株高之間均呈現直線相關，顯然吾人可以在生長期間取樣調查株高，再以之推估尼羅草之單位牧草生產量。
Subjects
Estimation
Forage production
Plant height
Nilegrass
Meteorological factor
Climatic model
估測
牧草生產
株高
尼羅草
氣象因子
氣象(候)模式
Publisher
台灣農藝學會
Type
journal article
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