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  • 期刊

屏東地區第一、二期作水稻之生態與收量之關係

Growth Performance and Yield of the Rice Plants in the First and Second Crop Seasons in Pingtung Area

摘要


爲探討屏東地區第二期作水稻單位面積產量較第一期作低落之原因,乃以嘉南8號爲主比較其在同一栽培管理但不同地力情形下(包括增收競賽歷年獲勝水田及一般水田)之兩期作生育過程,部份水田並設氮肥用量及栽植密度試驗,以探討葉面積指數與乾物生產之關係,結果獲致數點結論如下: (1)屏東地區第二期作水稻產量之低落可以歸因於全乾物收量之低落和谷莫比率之低下兩主要因素。 (2)第二期作全乾物收量之低落主要和葉面積指數(LAI)之低落有關。葉面積指數之低落預料係高溫下土壤中所發展之生育阻礙因素(例如土壤溶液中溶出過多鈣)影響稻根之鉀素吸收及分蘖所致。 (3)地力高之水田於第二期作時依然可獲如同第一期作程度之葉面積指數,谷收量亦較葉面積指數低落者高,惟因登熟期間單位葉面之淨同化率(Net Assimilation Rate)較低,谷真比率低落,其收量仍較第一期作爲低(第一、二期作各以出穗時LAI 5獲得谷收量7.2及5.8ton/ha, 75~85℃ oven dry basis)。 (4)第二期作登熟期間葉面淨同化率之低落予料和該生育期間之平均日射量較低事實有關(第一、二期各爲437及377g cal/cm^2/day),但從IR 8品種以更大葉面積指數獲得更多收量一事可以予料第二期作水稻受光態勢較劣亦是一個因素而將來由於品種之改良提高收量之希望很大。

關鍵字

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並列摘要


It is commonly acknowledged in Taiwan that the rice yield in the second crop is generally lower (15~20%) than that in the first crop. The trend is particularly significant in Pingtung area, the southernmost part of Taiwan (35%). By comparing the growth processes of Chianan 8 mainly under the two different crop seasons on a highly productive and a few normaly productive paddies in Pingtung, the following results were obtained. 1. Generally speaking, the low yield in the second crop in Pingtung area could be attributed to the general reduction of total dry matter and also to the relatively low grain to straw ratio of the plant. 2. The reduction of total dry matter was caused by low LAI (leaf area index) which was probably due to certain soil factors (e. g., high calcium level in soil solution) developed under high temperature responsible for the disturbances of potassium absorption by the plant and the reduction in tiller numbers. 3. Higher LAI which was obtained on the highly productive paddy in the same sea-son gave yield increase to a certain extent. However, because of its lower leaf efficiency (or Net Assimilation Rate) in dry matter production during the ripening stage, the grain to straw ratio was lower and the grain yield was not as high as that in the first crop (5.8 and 7.2 ton/ha, respectively with the same LAI of 5 at the flowering stage). The lower solar radiation (437 and 377g cal/cm^2/day, respectively for the ripening stage in the first and second crop season, respectively) might be a main cause attributed. However the morphologically inferior light receiving system of the plant in the second crop might also be a factor attributable since IR 8, a variety with a better plant type, got a higher yield with a higher optimum LAI in the same crop season.

並列關鍵字

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