施肥量對(duì)烤煙烘烤過(guò)程中多酚氧化酶活性的影響
發(fā)布時(shí)間:2019-08-23 來(lái)源: 美文摘抄 點(diǎn)擊:
摘要:以烤煙NC102為材料,研究不同的氮肥、磷肥和鉀肥施用量對(duì)烘烤過(guò)程中烤煙各部位煙葉多酚氧化酶活性的影響。結(jié)果表明:(1)氮(N)施用量高于5 g/盆對(duì)烘烤過(guò)程中各部位煙葉PPO活性均有提高作用,低于5 g/盆能夠顯著降低烘烤過(guò)程中中下部煙葉的PPO活性,上部煙葉的PPO活性沒(méi)有顯著降低;(2)磷(P2O5)施用量低于7.5 g/盆,能夠有效降低前72 h烘烤過(guò)程中的PPO活性,高于7.5 g/盆時(shí)各處理PPO活性沒(méi)有顯著變化;(3)鉀(K2O)施用量高于15 g/盆,提高下部煙葉的PPO活性,但顯著降低烘烤過(guò)程中PPO活性的峰值;鉀用量高于20 g/盆能顯著降低中上部煙葉在變黃后期和定色前期的PPO活性。
關(guān)鍵詞:氮磷鉀肥;烤煙;多酚氧化酶
中圖分類號(hào):S572.010.62文獻(xiàn)標(biāo)識(shí)號(hào):A文章編號(hào):1001-4942(2019)04-0089-05
Abstract In the study, the effects of different nitrogen,phosphate and potassium fertilizer application amounts on polyphenol oxidase(PPO) activity of flue-cured tobacco NC102 during baking were compared. The results were as follows. (1) The PPO activity of whole tobacco leaves during flue-curing improved when the nitrogen fertilizer application amount was above 5 g per pot. But that of middle and lower tobacco leaves reduced significantly when the application amount less than 5 g per pot, while the reduction of PPO activity was not significant in the upper tobacco leaves.(2) When the application amount of phosphorus (P2O5) was less than 7.5 g per pot, the activity of PPO could be effectively reduced in 72 hours after flue-curing, but had not significant change between treatments when the application amount was above 7.5 g per pot. (3) The potassium(K2O) application amount higher than 15 g per pot could increase the PPO activity of the lower tobacco leaves,but significantly reduced the peak value of PPO activity during flue-curing. The application amount of potassium fertilizer higher than 20 g per pot could significantly reduce the PPO activities of middle and upper tobacco leaves at the late of yellowing stage and pre-fixation.
Keywords Nitrogen-phosphate-potassium fertilizer; Flue-cured tobacco; Polyphenol oxidase
施肥是烤煙種植的重要措施之一。作為烤煙生長(zhǎng)過(guò)程中的大量元素,氮磷鉀起著重要作用。隨著氮磷鉀肥施用量的增加,煙株的株高、莖圍和最大葉面積增加,并且能提高煙葉的產(chǎn)量和質(zhì)量,同時(shí)煙堿和還原糖等內(nèi)含物質(zhì)均隨著不同營(yíng)養(yǎng)元素施用量的變化而呈現(xiàn)不同的變化趨勢(shì)[1-3]。
煙葉成熟后的烘烤調(diào)制過(guò)程中,由多酚氧化酶 (polyphenol oxidase,PPO)介導(dǎo)的酶促棕色化反應(yīng)將煙葉中的酚類物質(zhì)轉(zhuǎn)化為醌類化合物,導(dǎo)致煙葉顏色由黃色逐漸變棕變褐[4-6]。田間生長(zhǎng)中的煙葉,多酚類物質(zhì)位于液泡內(nèi),PPO位于質(zhì)體內(nèi),兩種物質(zhì)不能大量接觸,酶促棕色化反應(yīng)不易進(jìn)行[7]。煙葉調(diào)制過(guò)程中,溫濕度等外界因素的作用破壞了煙葉的細(xì)胞結(jié)構(gòu),PPO和多酚類物質(zhì)相互接觸,為酶促棕色化反應(yīng)創(chuàng)造了條件。
影響PPO活性的因素有很多。不同部位鮮煙葉PPO活性表現(xiàn)為上部葉﹥中部葉﹥下部葉,烘烤過(guò)程中也存在著不同的變化趨勢(shì)[8]。蘭俊榮等[9]研究指出,中下部煙葉PPO活性隨著采收成熟度的增加而降低,上部葉片PPO活性則增加。武云杰等[10]研究發(fā)現(xiàn),適當(dāng)推遲打頂能降低煙葉烤前和烘烤過(guò)程中的PPO活性,提高煙葉的易烤性和耐烤性。施肥上,不同施鉀量和氮鉀比對(duì)煙葉不同部位的PPO活性存在不同的影響,以鉀肥用量303.75 kg/hm2的處理最能改善煙葉的烘烤特性[11]。此外,馬曉林等[12]研究指出,施鉀使馬鈴薯葉片中多酚氧化酶活性顯著提高。也有研究表明,在0~5.84 g/盆范圍內(nèi),隨施磷量增加,煙葉氮磷鉀、多酚含量及PPO活性逐漸增加,均呈顯著正相關(guān),磷肥過(guò)多時(shí),抑制作用顯著[13]。
目前施肥對(duì)烤煙PPO活性影響的研究多集中在烤煙田間生長(zhǎng)階段,烘烤過(guò)程中的研究相對(duì)匱乏。因此,開(kāi)展氮磷鉀肥不同施用量處理下烤煙烘烤過(guò)程中的PPO活性變化動(dòng)態(tài)研究,可為烤煙生產(chǎn)中田間施肥調(diào)控提供理論依據(jù)。
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