• 作者： 李良
• 作者服務機構： 臺灣省農業試驗所嘉義農業試驗分所
• 中文摘要： 利用二個不同葉形態甘藷品種，在春作、夏作、秋作及冬作等四個不同期作環境下之試驗資料，供研究生理及環境因子對甘藷生長、收量與收量構成因素及品質等之影響程度，以期作為改進生產技術及選育適應不同栽培期作之早熟優良品種之參考。 在不同種植期作下，收穫指數一般均以生長初期為較低，而生長中期及後期之收穫指數為較高，此表示在生育中、後期，光合作用產物對塊根之分配量比莖葉多。全生育期平均，以夏作之收擭指數最低，為26.7%；而春作、秋作及冬作分別為 50.6%、50% 及 46.6%；品種間之收獲指數，以臺農65號比臺農57號高。 春、夏作之葉面積指數 (LAI) 均由植後60天達最高，60天以後，夏作 LAI 降低之速度較快，而春作 LAI 下降之幅度較漫，秋作以植後 90 天 LAI 達最高，90 天以後，則呈減低，冬作初期 LAI 小，而在植後 120 天達最高，由此結果可知，不同期作間 LAI 之變化，受栽培季節之氣候條件影響很大。 各生長期中，淨光合速率（NAR）之變化，不同期作間所表現趨向頗不一致，但同期作品種間 NAR 之變化大致相同，夏、秋作當 LAI 增最大時，NAR 減低，而春、冬作 LAI 大時，反而使 NAR 增高，故可知甘藷之栽培，初期生長非常重要，而在生育初期，必須加速莖葉擴展，但在生育中、後期，則應保持適當之莖葉生長，使塊根收量增加。 春、夏作甘藷在全生育期中，一般莖葉收量比塊根收量增加，而秋、冬作塊根收量比莖葉收量增加，此係由於不同期作生育期中氣象條件不同之影響所致，不同期作間塊根個數之差異不明顯，每個塊根均重；秋、冬作均比春、夏作有明顯之增加，此為構成秋、冬作之塊根收量比春、夏作增加之可能原因。 塊根乾物粗蛋白質含量之變化，以秋、冬作比春、夏作有明顯之增加，品種間塊根粗蛋白質含量，以臺農65號有顯著比臺農57號高，塊根乾物率及粗澱粉率以秋、冬作比春、夏作高，顆粒澱粉含量，秋作及夏作比冬作及春作有明顯之增加，而塊根汁液中可溶性固形物，春作及冬作
• 英文摘要： Four sets of data obtained from spring, sum-mer, fall and winter planting trials on two sweetpotato cultivars differing in their leaf morphologywere used to study the effect of phy, yield, yieldcomponents and quality of sweet potatoes. Theinformation thus gained will be used as refer-ences in the varietal and cultural imprc vements. The harvest index was in general low atearly growth stage and high at the middle andlate stages under different crop seasons. Thisshowed that a higher proportion of assimilateswas partitioned into the storage roots than thetops at the middle and late growth stages. Onan average over the entire growth period, thesummer planting showed the lowest harvestindex, 26.7%. For the spring, fall and winterplantings, they showed comparatively high har-vest index, 50.6%, 50% and 46.6%, respectively.The harvest index was generally higher for Tai-nung No. 65 than for Tainung No. 57. In the spring and summer plantings, the LAIreached a peak about 60 days after planting,and then declined. It was more slow in thespring planting, and rapid in the summer plant-ing. In the fall planting, the LAI reached amaximum about 90 days after planting, andthen decreased. For the winter planting, theLAI was low at early growth stage, but reachedthe highest value 120 days after planting. Theseresults indicated that the LAI differences amongcrop seasons is attributed to the variation ofclimatic conditions. NAR did not show consistent trend withdifferent crop seasons, but differences betweencultivars in the same planting season was almostsimilar. The present results showed that thegreat increases in LAI was associated with de-crease in NAR for the summer and fall plantings.In contrast, the NAR increased with the rela-tive increase of LAI for the spring and winterplantings. This would indicate that in sweetpotato cultivation, early growth is important, andtherefore, it is necessary to produce much topgrowth at the early stage and to maintain anoptimum top parts growth at the middle andlate stages of growth as to increase the pro-duction of roots yield. Generally, the summer and spring plantingshad produced high yield of tops and low yieldof roots, but the yield of tops was low and rootsyield was high for the fall and winter plantings.It is known that the climatic conditions of thedifferent crop seasons were considerably moreimportant in the determination of the yields.There was no difference in the number of rootsfrom all seasons. The average Wt. per root inthe fall and winter plantings were markedlyincreased compared with the spring and summerplantings, suggesting that differences in averageWt. per root were more likely to cause differencesin roots yield. The protein content in roots were signifi-cantly higher in the fall and winter plantingsthan in the spring and summer plantings. Therange varied from 3.6% to 5.5%. Tainung No. 65showed a considerable high crude protein contentthan Tainung No. 57. A high dry matter andcrude starch contents was shown for the falland winter plantings. The amylose content wasincreased markedly in the fall and summer plant-ings. The soluble solids content in roots werelow in the spring and winter plantings and highin the fall and summer plantings. Tainung No.65 had high soluble solids content than TainungNo. 57. Among the different crop seasons, the Ncontent in various parts of plant were generallyhigher at early growth stage, and then graduallydecreased, but the rate of decrease slowed downtoward the end of growth. The N content washighest in leaf blade, intermediate in stem andpetiole, and lowest in roots. The N content inroots between the cultivars is large, but thedifference in N content of leaf blade, stemand petiole between the cultivars were relativelysmall. Data in Table 4 showed that the seasonalfluctuation had a considerable effect on theessential amino acid contents. The total amountsof essential amino acids in the fall planting werehigher than in the spring, summer and winterplantings, and spring and summer plantings werealso higher than in the winter planting, butthere was no marked difference between springand summer plantings. These data showed thatTainung No. 65 had good nutritional quality inthe fall planting.
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