fa تأثیر محلول‌پاشی اسید هیومیک و تنش خشکی بر خصوصیات رشدی و فیزیولوژیک گل جعفری پژوهشي Research <p style="text-align: justify;"><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">گیاهان در دوران رشد خود با تنش‌ها</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">ی</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">متعدد</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">محیطی</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">مواجه</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">می‌شوند</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">. </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">هر</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">یک</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">از</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">این</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">تنش‌ها،</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">با</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">توجه</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">به</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">میزان</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">حساسیت</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">و</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">مرحله</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">رشد</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">گیاه،</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">می‌توانند</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">اثرهای</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">متفاوتی</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">بر</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">رشد،</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">متابولیسم</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">و</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">ع</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">ملکرد آن داشته باشند. یکی از راه</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">حل</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: sakkal majalla;">‌</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">ها</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">برای</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">کاهش</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">اثرهای</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">منفی</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">ناشی</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">از</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">تنش‌ها،</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">استفاده</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">از</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">مواد</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">هیومیک</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">است</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">. </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">مطالعه</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">حاضر</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">به</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: sakkal majalla;">‌</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">منظور</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">بررسی</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">تأثیر</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">اسید</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">هیومیک</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">و</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">تنش</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">خشکی</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">بر</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">شاخص</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: sakkal majalla;">‌</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">های</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">مورفولوژیک</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">و</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">فیزیولوژیک</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">گل</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">جعفری</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">صورت</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">گرفت</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">. </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">این</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">آزمایش</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">به‌صورت</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">فاکتوریل</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">و</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">در</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">قالب</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">ط</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">رح کاملاً تصادفی با سه تکرار طی پائیز و زمستان سال 1394 در گروه علوم باغبانی دانشگاه اراک به اجرا درآمد. در این تحقیق، تأثیر چهار سطح اسید هیومیک (صفر، 50، 100 و 250 میلی‌گرم </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">در</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">لیتر</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">) </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">و</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">سه</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">دوره</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">آبیاری</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;"> (5</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">،</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;"> 10 </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">و</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;"> 15 </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">روزه</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">) </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">بر</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">ویژگی</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: sakkal majalla;">‌</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">های</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">مورفولوژیک</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">و</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">فیزیولوژیک</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;"> گل جعفری (طول ریشه، تعداد برگ و گل، میزان کلروفیل </span></span></strong><strong><span dir="LTR"><span style="font-size: 9pt;"><span style="font-family: times new roman;">a</span></span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">، </span></span></strong><strong><span dir="LTR"><span style="font-size: 9pt;"><span style="font-family: times new roman;">b</span></span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;"> و کل، کارتنوئید، فسفر، کلسیم و پرولین) مورد ارزیابی قرار گرفت. نتایج نشان داد که با افزایش شدت تنش خشکی، طول ریشه‌ها </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">و</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">میزان</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">پرولین</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">افزایش</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">یافت</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">، </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">به</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: sakkal majalla;">‌</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">طوری</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">که</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">بیشترین</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">میزان</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">پرولین</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">در</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">تیمار</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">با</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">دور</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">آبیاری</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;"> 15 روز و بدون استفاده از اسید هیومیک و کمترین مقدار نیز در دور آبیاری 5 روزه و کاربرد 250 میلی‌گرم </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">در</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">لیتر</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">اسید</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">هیومیک</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">به</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: sakkal majalla;">‌</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">دست</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">آمد</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">. </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">با</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">این</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">حال،</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">تنش</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">خشکی</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">موجب</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">کاهش</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">تعداد</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">برگ‌ها</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">و</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">گل‌ها،</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">رنگیزه</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: sakkal majalla;">‌</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">های</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">کلروفیل</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;"> (</span></span></strong><strong><span dir="LTR"><span style="font-size: 9pt;"><span style="font-family: times new roman;">a</span></span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">، </span></span></strong><strong><span dir="LTR"><span style="font-size: 9pt;"><span style="font-family: times new roman;">b</span></span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;"> و کل)، کارتنوئید، میزان فسفر و کلسیم گردید. غلظت</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: sakkal majalla;">‌</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">های</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">بیشتر</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">اسید</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">هیومیک،</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">به‌ویژه</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;"> 250 </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">میلی‌گرم</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">در</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">لیتر،</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">میزان</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">کلروفیل</span></span></strong> <strong><span dir="LTR"><span style="font-size: 9pt;"><span style="font-family: times new roman;">a</span></span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">، کلروفیل </span></span></strong><strong><span dir="LTR"><span style="font-size: 9pt;"><span style="font-family: times new roman;">b</span></span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">، کلروفیل کل، کارتنوئید، فسفر، طول ریشه‌ها</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">،</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">تعداد</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">برگ</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">در</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">هفته</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">ششم</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">و</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">تعداد</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">گل</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">را</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">افزایش</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">داد؛</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">ولی</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">میزان</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">کلسیم</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">و</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">پرولین</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">را</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">کاهش</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">داد</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">. </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">تیمار</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;"> 250 </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">میلی‌گرم</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">در</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">لیتر</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">اسید</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">هیومیک</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">علاوه</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">ب</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">ر اینکه اثر منفی تنش خشکی را کاهش داد، توانست ویژگی</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: sakkal majalla;">‌</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">های</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">فیزیولوژیک</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">و</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">مورفولوژیک</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">را</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">بهبود</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">بخشد</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">. </span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">به</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: sakkal majalla;">‌</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">طور</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">کلی،</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">استفاده</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">از</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">اسید</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">هیومیک،</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">به‌ویژه</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">غلظت</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: sakkal majalla;">‌</span></span></strong><strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">های</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">زیاد</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">آن،</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">برای</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">افزایش</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">دور</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">آبیاری</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">گل</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">جعفری</span></span></strong> <strong><span style="font-size: 11pt;"><span style="font-family: b lotus;">پیشنهاد می‌شود. </span></span></strong></p> <p style="text-align: justify;">Plants are faced with various environmental stresses during their growing period. Each of these stresses have different effects on growth, metabolism and yield according to the sensitivity level and stage of the plant growth. One way of reducing the negative effects of the stresses is to use humic substances. The present study was carried out to evaluate the effects of humic acid and drought stress on morphological and physiological indices of marigold. The experiment was carried out according to the factorial arrangement, based on completely randomized design with three replications, in Department of Horticultural Science, Arak University, in fall and winter of 2016. The effects of four humic acid levels (0, 50, 100 and 250 mg/L) and three irrigation intervals (5, 10 and 15 days) was investigated on physiological and morphological traits of the marigold (root length, number of leaves and flowers, chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, phosphorus, calcium and proline contents). Results showed that root length and proline content was increased by increasing intensity of drought stress. The highest proline content was obtained by 15-day irrigation interval without humic acid and the lowest content was obtained by 5-day irrigation interval with 250 mg/L humic acid. However, drought stress reduced number of leaves and flowers, chlorophyll (a, b and total), carotenoid, and phosphorus and calcium contents. Higher levels of humic acid, particularly 250 mg/L, increased the amount of chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, phosphorus content, root length, number of leaves in the sixth week and number of flowers; but reduced the calcium and proline contents. The 250 mg/L humic acid treatment not only reduced the negative effect of drought stress, but also was able to improve the physiological and morphological characteristics. In conclusion, using humic acid, especially at higher concentrations, is recommended for increasing the irrigation interval of marigold flower.</p> اسید هیومیک, تنش خشکی, فسفر, کلروفیل Chlorophyll, Drought stress, Humic acid, Phosphorus 67 80 http://jspi.iut.ac.ir/browse.php?a_code=A-10-736-3&slc_lang=fa&sid=1 M. Dalvand مریم دالوند No Dept. of Hort. Eng., Faculty of Agric. and Nat. Resour., Arak Univ., Arak, Iran گروه مهندسی باغبانی، دانشکده کشاورزی و منابع طبیعی، دانشگاه اراک M. Solgi موسی سلگی m-solgi@araku.ac.ir Yes Dept. of Hort. Eng., Faculty of Agric. and Nat. Resour., Arak Univ., Arak, Iran گروه مهندسی باغبانی، دانشکده کشاورزی و منابع طبیعی، دانشگاه اراک A. Khaleghi علیرضا خالقی No Dept. of Hort. Eng., Faculty of Agric. and Nat. Resour., Arak Univ., Arak, Iran گروه مهندسی باغبانی، دانشکده کشاورزی و منابع طبیعی، دانشگاه اراک