Studying the effects of water deficit stress and weed competition on the yield and biochemical composition of tubers of new potato cultivars

Abstract

Background and Objectives:

Potato (Solanum tuberosum L.) is the fourth most important food crop in the world after wheat, rice, and maize, and due to its production potential, it can play a significant role in global food security. Nowadays, with the intensification of the water scarcity crisis, its production faces serious challenges, further exacerbated by the presence of weeds, the hidden bioterrorists of agricultural ecosystems. Plants, in response to such conditions, exhibit various biochemical reactions, including proline accumulation, enhanced activity of antioxidant enzymes such as peroxidase, and changes in hydrogen peroxide (H2O2) concentration. These indicators represent the plant’s defense mechanisms against stress and can serve as criteria for identifying tolerant cultivars. The aim of this study was to investigate the interactive effects of water deficit stress and weed competition on the biochemical traits and yield of three new potato cultivars.

Materials and Methods:

The experiment was conducted during the 2023 growing season at the Potato Research Farm of the Agricultural Research Center of Ardabil, in a split-factorial design based on a randomized complete block design (RCBD) with three replications. The main factor included three irrigation levels (100, 75, and 50% of field capacity), the first sub-factor included two competition levels (with and without weeds), and the second sub-factor included three potato cultivars: Agria, Rona, and Takta. Biochemical indices, including proline, peroxidase enzyme, and leaf H2O2, were measured, and at the end of the growing season, tuber yield and water use efficiency were recorded. Data were analyzed using analysis of variance (ANOVA) and mean comparison.

Results:

The results revealed that drought stress and weed competition significantly affected biochemical traits and yield. Weed competition increased proline content by an average of 13%. Drought stress also led to an increase in proline, such that under 75% and 50% field capacity treatments, proline levels were 27.5% and 52.7% higher than the control, respectively. Among the cultivars, Takta exhibited the highest proline accumulation under drought and competition conditions, whereas Rona showed the lowest response. Weed competition also enhanced peroxidase activity, particularly in Takta under non-stress conditions, where it was 25% higher. Hydrogen peroxide (H2O2) concentration varied among cultivars: in Agria and Rona, the presence of weeds reduced H2O2 levels, while in Takta, an increase was observed. Tuber yield was strongly affected; weed competition reduced yield by an average of 7 t/ha. The greatest yield reduction occurred in Rona (16.5%), while Takta showed the lowest reduction (11%). Moreover, severe drought stress caused a 34% yield decline. Evaluation of water use efficiency indicated that, with increasing stress intensity, water use efficiency improved, particularly in Agria under severe drought without weed competition.

Conclusions:

The present study demonstrated that potato cultivars respond differently to drought stress and weed competition, and that variations in proline, peroxidase, and H2O2 are key indicators of tolerance. Cultivars such as Agria (with higher water use efficiency) and Takta (with greater proline accumulation) showed higher potential for cultivation under conditions of water deficit and weed competition. These findings can be utilized in breeding programs and the development of management strategies aimed at enhancing the sustainability of potato production under biotic and abiotic stresses.