• 作者： 朱鈞; 郭華仁; 邱淑芬
• 作者服務機構： 國立臺灣大學農藝學系
• 中文摘要： 取?型水稻臺北306號等三品種及秈型水稻矮腳尖等二品種，分一、二期作種植於田間，開
  花盛期時，臺北360號及矮腳尖每期各選1,700穗為樣品，在抽穗後頂端小穗開花之當天掛牌登
  記開花日期。總樣品之一半並做剪小穗處理，即除了頂端三小穗外，其餘穎花全部剪掉。對照組
  則不剪穎。開花後每隔三至四天取樣一次，取頂端20粒，稱量其鮮重、乾重、碳水化合物及蛋
  白質含量，並比較其充實特性。其餘品種則於各期作，分剪小穗及對照兩組，於成熟後，採收取
  頂端20粒稱量米粒乾重。
  第一期作臺北306號及矮腳尖穀粒生長的滯留期約二天，有效充實期分別為13.4天及10.8
  天，直線充實速率分別為1.22及1.43毫克／粒／天。最後去殼的乾重分別為每粒16及15毫克。
  第二期作臺北306號及矮腳尖穀粒生長的滯留期分別為5.8天及4天，有效充實期均為16天
  ，直線充實速率分別為0.89及0.80毫克／粒／天，最後去殼乾重分別為每粒14.6及14.5毫克。剪
  小穗處理可以縮短滯留期，提高直線充實率。對第二期作而言，又可延長有效充實期，因此穀粒
  最後乾重較對照組為高，穀粒水分含量的高?，恰在乾物蓄積速率最高之時，顯示二者間相當密
  切之關係。
  澱粉的蓄積與乾物的蓄積過程頗為相似，但穀粒生長前期，澱粉所佔乾重百分比，較後期稍
  低。糖分的含量，一般約在穀粒生長速率最快時達高?。蔗糖為構成穀粒總醣的主要成份，惟穀
  粒急速生長時稍有下降，顯示此時澱粉的合成甚快，一期作時在充實末期蔗糖含量再度升高，顯
  示此時穀粒本身限制其充實能力，而二期作穀粒內同化物質之多寡可能為限制穀粒發育之主要因
  素。蛋白質蓄積的特性與澱粉相似。其蓄積速率或蓄積量與穀粒所含游離氨基態氮的含量有關。
• 英文摘要： In order to clarify the causes of low yieldin the second crop of rice in northern area ofTaiwan, the filling process of rice grains underdifferent croppings shoud be eluciated at first. Three japonica cultivars: Taipei No. 306,Taichung No. 65 and Hsinchu No. 56, and twoindica cultivars: Ai-Chau-Cheng and Chia-NungShien 11 were planted in the experimental farmstation, N. T. U. in the first and the secondcrop. When the plants reached the maximumflowering stage, 1700 panicles for each crop ofTaipei No. 306 and Ai-Chau-Cheng were chosenas samples. The date of anthesis of the distalflowers for each panicle was recorded. In halfof the samples, most of the spikelets in an earwere detached leaving 3 distal branches in eachpanicle. The other half samples remained intact.After four days of anthesis, panicles were har-vested every 3 or 4 days. Twenty grains of the3 distal branches were collected. Changes offresh weight and carbohydrate contents as wellas the filling characters of grains were measuredand compared between croppings and/or culti-vars. With the rest of the cultivars, two hun-dred panicles per cultivar per crop were chosenand the subjected to partial spikelet eliminat-ing treatment and control groups. After fullripening, each sample was harvested and twentygrains of the three distal branches were collect-ed and the dry weight of kernels was meas-ured. In the 1st crop, the lag period of grainfilling was 2 days in spite of cultivars. Effec-tive filling period was 13.4 and 10.8 days, linearfilling rate was 1.22 and 1.43 mg/dehulled grain/day, and final dry weight was 16 and 15 mg/dehulled grain for Taipei No. 306 and Ai-Chau-Cheng, respectively. In the 2nd crop, effectivefilling period was 16 days for both cultivars.Lag period was 5.8 and 4 days, linear growthrate was 0.89 and 0.80 mg/dehulled grain/day,and final dry weight was 14.6 and 14.5 mg/dehulled grain for Taipei No. 306 and Ai-Chau-Cheng respectively. Partial spikelet eliminatingtreatments resulted in a shorter lag period, andalso resulted in a longer effective filling periodin the 2nd crop, thus their final grains weightswere heigher than those of the controls. Water content per grain increased with daysafter anthesis, reached a climax after 7 and 12days for the 1st and the 2nd crop, respectively,then decreased afterwards. The climax appearedconcurrently with that of daily filling rate, whichsuggested a close relationship between watercontent and grain filling process. The pattern of starch accumulation wassimilar to that of dry matter accumulation,which was indicated by rapid growth rate,shorter filling period and higher filling periodand higher final content of starch in the 1stcrop. But the percentage of starch in the drymatter of a dehulled grain was a little lower atearly filling stage than that at latter filling stage. Sugars always reached the highest quantityat the most rapid growth of the grain regardlessof crop seasons. Sucrose, being synthesizedin leaves and from where being translocated intograins and then transformed into starch, wasthe main constituent of total sugars in a deve-loping grain, except at the most rapid growthperiod. The decrease of sucrose/total sugarsratio might be caused by rapid starch synthesis.In the final period of grain growth of the 1stcrop, little starch or dry matter was producedinto the kernel, and the sucrose content risedagain suggesting that sucrose may not be a li-miting factor for grain growth at that time.But as in the 2nd crop, the limited supply ofthe assimilate rather than grain filling capacityper se might be the main restriction of graingrowth. The pattern of protein accumulation wassimilar to that of the dry matter accumulation,and was correlated with free amino-N contentin the kernel.
• 中文關鍵字： --
• 英文關鍵字： --