Document Type : Research Article
Author
Soil and Water Research Department, Khouzestan Agricultural and Natural Resources Research and Education Center AREEO, Ahvaz, Iran
Abstract
Introduction
Potato 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 well-known 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 Methods
This 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 2019-2020. 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 acid-Zn, amino acid-K, amino acid-Ca, amino acid-K-Ca 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.ha-1 in the early stages of growth. Foliar application of amino acid, amino acid-Zn was done at two stages, tuber initiation and the beginning of tuber bulking. Foliar application of amino acid-K, amino acid-Ca was done at two stages, the beginning and middle of tuber bulking. Amino acid and amino acid-nutritional 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 Discussion
The 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 acid-K, amino acid-Ca and amino acid-K-Ca 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 acid-Zn were more effective than other treatments. But, in the third and fourth sampling periods, treatments of amino acid-K, amino acid-Ca 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.
Conclusion
According 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 acid-K-Ca 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 acid-K, amino acid-Ca and amino acid-K-Ca and humic acid were not significant. Therefore, based on the finding of the present study, it could be concluded that treatments of amino acid-K, amino acid-Ca or humic acid may be an effective growth biostimulants for improving yield of Ottawa cultivar.
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