右表是对农作物I和农作物II在同一土壤中N、P、K三要素肥效试验结果。“+”表示施肥，“一”表示未施。下列结论正确是（    ）。 <table border="1" cellspacing="0" cellpadding="0" _dj="MsoNormalTable"><tbody><tr><td rowspan="2" width="82"> </td><td width="163" colspan="3">肥料成分</td><td rowspan="2" width="102">实验产量与原产量比(%)</td></tr><tr><td width="54">氮肥</td><td width="54">磷肥</td><td width="54">钾肥</td></tr><tr><td rowspan="5" width="82">农作物Ⅰ</td><td width="54">－</td><td width="54">－</td><td width="54">－</td><td width="102">68</td></tr><tr><td width="54">－</td><td width="54">＋</td><td width="54">＋</td><td width="102">100</td></tr><tr><td width="54">＋</td><td width="54">－</td><td width="54">＋</td><td width="102">70</td></tr><tr><td width="54">＋</td><td width="54">＋</td><td width="54">－</td><td width="102">89</td></tr><tr><td width="54">＋</td><td width="54">＋</td><td width="54">＋</td><td width="102">100</td></tr><tr><td rowspan="5" width="82">农作物Ⅱ</td><td width="54">－</td><td width="54">－</td><td width="54">－</td><td width="102">35</td></tr><tr><td width="54">－</td><td width="54">＋</td><td width="54">＋</td><td width="102">48</td></tr><tr><td width="54">＋</td><td width="54">－</td><td width="54">＋</td><td width="102">68</td></tr><tr><td width="54">＋</td><td width="54">＋</td><td width="54">－</td><td width="102">91</td></tr><tr><td width="54">＋</td><td width="54">＋</td><td width="54">＋</td><td width="102">100</td></tr></tbody></table>