Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/36725
標題: 台灣地區水稻品種之光能利用效率分析及其判別函數的建立
Solar radiation use efficiency and its discriminant functions of the rice varieties released un Taiwan
作者: 羅正宗
Lo, Jeng-Chung
關鍵字: rice;水稻;solar radiation use efficiency;discriminant function;光能利用效率;判別函數
出版社: 農藝學系
摘要: 
本研究之目的在建立台灣地區水稻稻穀產量之光能利用效率(RUEy)的判別函數,以作為選育高光能利用效率的水稻品種之用。由於產量之光能利用效率需涉及水稻植冠對日光輻射之截取能力,及植冠所截取之日光輻射形成稻穀產量之效率;因此,本試研究首先針對過去台灣地區過去六十年來育成的水稻品種進行植冠截光率(MLI)及光能利用效率的品種變異性分析,及其在不同育種年代中的遺傳演進,並進一步探討水稻植冠發育之相關性狀與MLI及RUEy的關係,作為建構判別函數所需之變數選擇的依據。
逢機選取25個過去六十年來台灣地區育成的水稻品種為材料, 進行水稻MLI之品種變異性及其遺傳演進之探討。結果顯示品種間雖具有顯著的變異性,但以兩期作之數據進行合併分析,水稻MLI之遺傳率及遺傳增進量均甚低,顯示水稻MLI是一個相當不穩定的性狀;但若在各期作內分別估算,則遺傳率及遺傳增進量均明顯地提高。其中以第二期作施用180公斤氮肥及第一期作不施氮肥的條件下之水稻MLI的育種效應顯著地比其他試驗條件下之育種效應高。此外,植冠發育之相關性狀與水稻MLI間均具有顯著的相關性,但以抽穗期之LAI與MLI關係最密切,可作為水稻品種選育的參考性狀;而此參考性狀在第二期作施予180公斤氮肥之環境下,具較高之遺傳率及遺傳增進量。
二十五個參試水稻品種之MLI值在第一期作下,並未依育種年代演進而呈顯著的改變。但在第二期作不施氮肥及施以180公斤氮肥的條件下, MLI值之遺傳增進量呈現直線減少的趨勢。另由參試品種之植冠平均截光效率(LIE)進行遺傳改良成果的週期性評估, 顯示台灣地區育成的水稻品種之LIE隨育種年代演進而增加或遞減的情形並不明顯, 換言之,老品種雖具有較高的MLI, 但其LIE並不高於新近育成的品種。
就RUEy而言,25個參試品種在第一期作之表現明顯高於第二期作,新近育成之品種的RUEy會因氮肥之施用而提高,而老舊品種在高氮肥的環境下則可能因倒伏而降低其RUEy。由綜合變方分析的結果顯示水稻RUEy為一相當穩定的性狀,品種與環境因子間並未呈現顯著地交感作用。就育種選拔效應而言,應以第二期作施用氮肥的環境下較高。由相關分析的結果顯示水稻RUEy與植冠發育相關性狀間關係並不密切。
不同年代育成的參試品種,在氮肥施用的環境下,RUEy值隨育種年代之演進而呈直線增加的趨勢,且增加的效應會因氮肥施用量之增加而提高,唯此種關係在不施氮肥環境下則不易顯現出來。
為了分析水稻穀粒產量的品種變異性,本試驗以總日光輻射截取量(LIsum)及產量之光能利用效率(RUEy)的乘積用以表達水稻稻穀產量。相同地,以總乾物重之光能利用效率(RUEtdw)及收穫指數(HI)之乘積用以表達RUEy。分析結果顯示當參試品種處以90公斤氮肥施用量時,LIsum對穀粒產量之變異性的影響較高;然而在施以180公斤氮肥或不施氮肥的環境下,則RUEy對穀粒產量之變異性較高。另就RUEtdw及HI對RUEy之變異性的影響而言,在各種氮肥施用量下,RUEtdw對RUEy之變異性的影響均大於HI。在此情況下,產量受制於RUEy的高比例變異均為透過RUEtdw所達成。
為使本研究所建立之判別函數能準確地鑑別一水稻品種之RUEy,先在各個試驗環境下進行供試品種的分群分析(clustering),再以多變數變方分析決定分群之群數,以達到群內變異最小,群間變異最大的要求。結果顯示除第一期作90公斤氮肥施用量下可分為四群外,其它試驗環境下均以分成三群較為適當。建構判別函數之性狀,乃依因子分析之結果,選取在相同主因子中與RUEy關係密切之性狀。本研究依不同環境所建立之六組判別函數,均具有顯著的判別能力,可將低RUEy群明確地區隔出來,依此,在水稻品種選育的過程中,可清楚的鑑別低RUEy個體而予以淘汰,減少育種工作量,有利於選育工作之進行。

Solar Radiation Use Efficiency and Its Discriminant Functions of the Rice Varieties Resealed in Taiwan
Abstract
This study aimed to explore a set of canonical discriminant functions, i.e., linear combinations of certain quantitative traits, that best reveal the difference of solar radiation use efficiency of grain yield (RUEy) among rice varieties. A total of 25 varieties randomly selected from the collection of rice varieties released in Taiwan during the past 60 years were used to conducted field experiments with various nitrogen rates and/or planting densities in the first and the second crop seasons through the years from 1997to1999. Plant height, tiller number, leaf area index , leaf inclination angle, light interception rate, and total shoot dry weight were periodically measured throughout the growing season, and grain yield and its components, i.e., panicle number, spikelet number per panicle, ripen rate and 1000-grain weight were also recorded at harvest. RUEy was calculated as the ratio of grain yield to the total intercepted solar radiation (LIsum), which in turn was the product of the total incoming radiation and the mean light interception rate (MLI).
The MLI value of rice canopy, although significantly different among the test varieties, was unstable across the range of the experiments. Both the estimates of heritability (intra-variety correlation) and genetic gain of MLI were low from a combined analysis on the pooled data. When data were analyzed separately for each of the two crop seasons, however, the estimates of these two genetic parameters of MLI raised remarkably. It revealed that varieties with high MLI value might best be identified under the conditions of applying 180 Kg nitrogen per hectare in the second crop season or applying no nitrogen in the first crop season. As expected, many characteristics of the rice canopy were significantly correlated with MLI. Among them, the LAI at heading, which showed high heritability and genetic gain, was correlated with MLI very closely. This suggested that selection for variety with high MLI could be accomplished by the way of selection for LAI at heading.
When grown with no nitrogen fertilizer or with 180 Kg nitrogen per hectare in the second crop season, the MLI of the test varieties showed a clear decreasing trend over the time the varieties were released. Such a time trend was not detected in the first crop season. Besides, no significant evolution pattern in the mean light interception efficiency (LIE), i.e., the ratio of MLI to LAI, was observed in the range of the experiments. In other words, the older varieties showed higher MLI but not higher LIE.
All the test varieties gave higher values of RUEy in the first crop season than in the second crop season. The varieties released in recent years showed higher RUEy when they were fertilized with more nitrogen. But, the reverse was true for the old varieties. No significant GxE interaction was found in the analysis of variance of RUEy, which indicated that RUEy was a rather stable character of the rice varieties released in Taiwan. However, higher estimates of the heritability and genetic gain of RUEy were obtained when these varieties were fertilized with nitrogen in the second crop season. This suggested an efficient environmental condition for the selection of varieties with high RUEy. No significant correlation was detected between RUEy and other canopy characteristics investigated in this study. In general, the test varieties showed an increasing time trend of RUEy in respect to their breeding era . This trend was absent when these varieties were grown with no nitrogen fertilizer.
To elucidate the varietal variation of grain yield and RUEy, grain yield was expressed as the product of LIsum and RUEy, which in turn was expressed as the product of radiation use efficiency of total dry matter production (RUEtdw) and harvest index (i.e., ratio of grain yield to total dry matter production, HI). The variance of grain yield was mainly accounted for by LIsum when the varieties were fertilized with 90 Kg nitrogen per hectare. However, RUEy took the role in determining the variation of grain yield when these varieties were fertilized with 180 Kg nitrogen per hectare or no nitrogen fertilization. On the other hand, contribution of RUEtdw to the varietal variance of RUEy was much higher than HI across the treatment levels of nitrogen rate. In sum, grain yield of a variety was mainly determined by its RUEy, which in turn was affected greatly by the RUEtdw of the variety when it was fertilized with certain amount of nitrogen.
As a provision to develop the discriminant functions for RUEy, the test varieties were clustered, by a nonhierarchical clustering algorithm, into three to five groups according to their RUEy values evaluated in each of the six treatment combinations of the two crop seasons by the three levels of nitrogen rate. The optimal number of variety group was determined so as to maximize the among-group variance and to minimize the within-group variance of RUEy simultaneously. The result showed that the test varieties could adequately be separated into three groups except the treatments with 90 Kg nitrogen per hectare, which a four- group clustering seemed optimal. A set of two discriminat functions for RUEy were established for each of the six treatment combinations. Owing to their significant ability in identifying the varieties with low RUEy, a breeding program would be much more efficient to improve the RUEy of rice varieties if these discriminant functions were employed.
URI: http://hdl.handle.net/11455/36725
Appears in Collections:農藝學系

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