ارزیابی محرک‌های رشد گیاهی بر شاخص‌های رشد، عملکرد و اجزای عملکرد ارقام سیب‌زمینی

این پژوهش به‌منظور بررسی تاثیر محرک‌های رشد گیاهی بر شاخص‌های رشد و خصوصیات ارقام سیب‌زمینی در دو مطالعه انجام شد. مطالعه اول به‌صورت فاکتوریل در قالب طرح بلوک‌های کامل تصادفی با سه تکرار در ایستگاه تحقیقات کشاورزی بهبهان در سال زراعی 99-1398 اجرا شد. فاکتور اول شامل دو رقم سیب‌زمینی: اوتاوا و سانته بود. فاکتور دوم شامل هشت تیمار: اسید هیومیک، اسید آمینه آزاد، اسید آمینهعنصر غذایی (zn، k، ca و kca)، مصرف توام تیمارها (به‌جز اسید آمینه) و شاهد بود. در مطالعه دوم، شاخص‌های رشد با استفاده از آزمایش اسپلیت‌پلات فاکتوریل بر پایه طرح بلوک‌های کامل تصادفی با سه تکرار ارزیابی شدند. فاکتور اصلی پنج دوره نمونه‌برداری و دو رقم و هشت محرک رشد به‌صورت فاکتوریل، به‌عنوان فاکتور فرعی در نظر گرفته شدند. در رقم سانته بیشترین عملکرد غده مربوط به تیمار مصرف توام بود و نسبت به بقیه تیمارها برتری معنی‌داری داشت. در رقم اوتاوا نیز حداکثر عملکرد مربوط به تیمار مصرف توام بود ولی نسبت به اسید آمینه‌های پتاسیم یا کلسیم‌دار و اسید هیومیک برتری معنی‌داری نداشت. نتایج آنالیز رشد مشخص نمود در بیشتر دوره‌های نمونه‌برداری سرعت رشد غده و محصول تیمار مصرف توام از سایر تیمارها بیشتر بود. لذا حداکثر عملکرد غده به این تیمار اختصاص یافت. در دوره‌های مختلف نمونه‌برداری سرعت رشد غده و محصول در رقم اوتاوا به‌طور معنی‌داری بیشتر از رقم سانته بود. بر اساس نتایج این پژوهش، در رقم سانته کاربرد توام محرک‌های رشد و در رقم اوتاوا کاربرد اسید آمینه‌های پتاسیم یا کلسیم‌دار یا اسید هیومیک توصیه می‌شود.

Evaluation of Plant Growth Biostimulants on Growth Indices, Yield and Yield Evaluation of Plant Growth Biostimulants on Growth Indices, Yield and Yield Components of Potato CultivarsComponents of Potato cultivars

IntroductionPotato plays an important role in global food security and it growth and tuber yield are influenced by many biotic and abiotic stresses, such as drought and low or high temperatures. Potato in Khuzestan province is facing unfavorable weather conditions, especially high temperature. Humic acid and amino acid, as wellknown biostimulants, can directly or indirectly influence on plant growth and yield and significantly mitigates the injuries caused by abiotic stresses. In some studies, the use of humic acid has been reported increase root length, improve nutrient uptake, and increase chlorophyll synthesis. Amino acids in potato plant increase natural resistance to stresses. It seems that biostimulants and some nutrition elements can be applied as a strategy to reduce the negative effects of high temperatures. Therefore, this study was conducted to evaluate the effect of plant growth biostimulants on growth indices, yield and yield components of potato cultivars in Khuzestan region.Materials and MethodsThis research was conducted in two studies. First study was carried out as a factorial experiment in a randomized complete block design (RCBD) with two factors including 16 treatments in three replications at Behbahan Agricultural Research Station in 20192020. The first factor was application of plant growth biostimulants at eight levels: control (application of chemical fertilizers according to soil test), humic acid, free amino acid (L), amino acidZn, amino acidK, amino acidCa, amino acidKCa and application of all studied biostimulants (except free amino acid). The second factor consisted of two potato cultivars: ’Ottawa and Sante’. In the second study, growth analysis was done in a split plot factorial based on RCBD with three replications. Main plot consisted of five sampling periods with 15 days intervals. Sub plot consisted of combination of eight plants growth biostimulants and two cultivars of potato as factorial. Tubers were planted at mid January. One week before harvesting haulms were defoliated and tubers were harvested at mid May. Humic acid was used as fertigation at 10 kg.ha1 in the early stages of growth. Foliar application of amino acid, amino acidZn was done at two stages, tuber initiation and the beginning of tuber bulking. Foliar application of amino acidK, amino acidCa was done at two stages, the beginning and middle of tuber bulking. Amino acid and amino acidnutritional element were done at a concentration of 0.5 %. Varince analysis were done by MSTATC statistical software and meanes were compared using Duncan’s multiple test range at the 5% level.Results and DiscussionThe results showed that in two cultivars, application of all studied biostimulants (except free amino acid) significantly increased tuber yield compared with control. In Sante cultivar, the highest yield was dedicated in the treatment of combined, and the yield of this treatment was significantly higher than the yield of  alone application of these substances. In Ottawa cultivar, the highest yield was achieved by application of combined biostimulants, but the differences of tuber yield among this treatment and treatments of amino acidK, amino acidCa and amino acidKCa and humic acid were not significant. The results of growth analysis showed, in the most sampling periods, the highest tuber and crop growth rate were recorded in the combined treatment. Therefore the highest tuber yield was observed in this treatment. In the first and second sampling periods, application of humic acid or amino acidZn were more effective than other treatments. But, in the third and fourth sampling periods, treatments of amino acidK, amino acidCa were more effective in comparision to alone of these substances. In different sampling periods, tuber and crop growth rate in Ottawa cultivar was significantly higher than Sante cultivar.ConclusionAccording to results, in Sante cultivar, the combined treatment of plant growth biostimulants produced the highest yield in comparision to any individuals of these substances. Therefore, use of humic acid as fertigation in the early stages of growth and foliar application of amino acid Zn at two stages tuber initiation and the beginning of tuber growth and amino acidKCa at two stages the beginning and middle of tuber growth, are recommended. In Ottawa cultivar, the differences of tuber yield among treatment of combined application of growth biostimulants, amino acidK, amino acidCa and amino acidKCa and humic acid were not significant. Therefore, based on the finding of the present study, it could be concluded that treatments of amino acidK, amino acidCa or humic acid may be an effective growth biostimulants for improving yield of Ottawa cultivar.