台灣秈稻栽培面積之減少及其原因之探討

Abstract

1. 三十年來本省秈稻栽培面積平均以每年9.615公頃之速度逐年減少，至民國七十六年有全部消失可能。 2. 此項減少為全省性之現象，但以第二期作及低產地區之減少比率為大。十數年來秈稻二期作的單位面積產量成長較緩慢。 3. 秈稻栽培面積減少原因歸納為：(1)秈型稻穀官訂價格偏低，係受市場要求及容重量不足之影響，(2)秈稻於一般水田的單位面積產量及適應性較差。 4. 為改良秈米之烹飪品質，雜種初期世代的個體選拔，採用膠體軟度(gel consistency)篩選，成立品系後再以顆粒澱粉含量篩選，比較方便。 5. 榖粒容重量與粒長，粒幅和穀粒間空隙各有-0.82**，0.72**和-0.90**之相關係數。糙米率與粒長有-0.63**~-0.67**的相關。榖米細長使空隙增加而容重量降低，同時糙米粒也減少。 6. 七十五個早熟秈型品種的粒長、粒幅、千粒重與產量無顯著之相關關係，故秈稻的高度潛力似由於半矮性，而非長粒型之故。 1. The total area planted to indica rice in Taiwan has been decreasing by 9,615 hectares a year in average since 1948. If this rate continues as such, indica rice will disappear from the ordinary rice paddies on the island within 10 years from now. 2. Although the area drop is a provincial phenomenon, it is most drastic in the second rice crop and in low-yielding districts, where the growth of yield per unit area is slow. 3. The causes of acreage drop are considered to be: (1) lower price of indica rice than that of Ponlai rice set up by the government because of its smaller volume-weight of the grains and less demand in the domestic market; and (2) its lower yield and unstability as compared with Ponlai rice in the ordinary rice paddies. 4. In order to simplify the testing method for cooking quality, it is suggested to use gel consistency in screening for the plants in early segregating generations, and to use amylose content for further screenging after the establishment of the strains. 5. The volume-weight of rice grains was significantly correlated with grain length (-0.82**), grain width (0.72**) and air space between grains (-0.90**). The coefficient between milling rate and length of polished rice was from -0.63** to -0.67**. Long slender grains allow more air space between the grains to reduce the volume-weight, and also introduce a reduction of the brown rice milling rate by 1.996% per mm. of the length. 6. No significant correlation was found between yield per unit area and 3 grain characteristics namely grain length and width and 1,000 grain weight, in 75 early-maturing indica varieties. It seems that high yielding is not associated with the lenght of the grain.