【正文】 positions during harvest is extremely important to producing a quality, highdemand product regardless of the buying pany (See Figure 1). Cigarette manufacturers and leaf dealers have different preferences for the styles of tobacco they desire to meet customer needs. For example, some cigarette manufacturers would like to see greater production of tip grades for use in blending while others would like to buy less lowerstalk tobacco. 因此，在收獲期間將煙葉按不同部位進行劃分對生產(chǎn)高質(zhì)量、高需求的產(chǎn)品是極其重要的。研究包括K32NC71和speight 168品種，對推薦氮用量和在推薦氮用量基礎(chǔ)上加20磅N以及高打頂和正常高度打頂進行了比較。Removal of four leaves resulted in a 6 percent average reduction in yield and gross value per acre. Removing eight leaves resulted in a 20 percent average reduction in yield and gross value per acre. However, reduced curing and labor costs due to leaf removal would make the reduction in net value per acre less than the reduction in gross value.去除4片葉導致每英畝產(chǎn)量和毛產(chǎn)值下降6％，去除8片腎卜導致每英畝產(chǎn)量和毛產(chǎn)值下降20％。Additional research was conducted to evaluate removing either the bottom four or eight leaves as a way to reduce production of priming grades (Table 83). Preliminary data from this study indicates that removal of the bottom four leaves eliminates priming grades and the removal of the bottom eight leaves eliminates priming and lug grades. 為了評估除去底部4或8片葉以減少腳葉等級的方法，進行了另外的研究(表83)。但是僅靠將最上部葉片分開采收，還不足以生產(chǎn)出具有頂葉等級的理想的化學和物理特性的煙葉。卷煙不僅僅是幾種類型煙草的混合，而且是幾種類型煙草的不同部位煙葉的混合。處理5所有參試品種的產(chǎn)量和產(chǎn)值均有損失。然而第三次采摘是按照在以下時間完成進行處理：treatment 1, 7 days earlier than ideal ripeness。2002生長季節(jié)與2003和2004生長季節(jié)是兩個相反的極端。Higher yields reduce perpound production costs for acreagerelated inputs such as chemicals, fertilizers, and some labor expenses. Topping early also improves chemical and physical qualities of the leaf by stimulating root development and alkaloid production and by reducing buildup of insects.高產(chǎn)減少了與面積相關(guān)的生產(chǎn)成本，如農(nóng)藥、肥料和一些勞動力支出。 ●霜霉病更加嚴重。 很多農(nóng)藝措施影響煙草的質(zhì)量，最重要的一些措施有：? Nitrogen rate and time of application ? Topping and sucker control with minimal MH residues? Harvest rate and ripeness? Leaf separation by stalk position●氮肥的施用量和施用時間 ●打頂和最少馬來酰肼殘留的腋芽控制 ●采收速率和成熟度 ●葉片分部位采收Nitrogen Rate and Time of ApplicationNitrogen is the most important nutrient affecting tobacco yield and quality. As nitrogen rate increases, the following occur:? Yield increases to a point then decreases.? Leaf size increases, but leaf thickness decreases.? Total alkaloids, including nicotine, increase and sugars decrease in the cured leaf.? Maturity and ripening are delayed. ? Cured leaf darkens.? Sucker growth increases and sucker control decr