Physiological and Morphological Responses of Okra (Abelmoschus esculentus L.) to Rhizoglomus irregulare Inoculation under Ample Water and Drought Stress Conditions Are Cultivar Dependent

Abstract

Okra is an important crop species for smallholder farmers in many tropical and subtropical regions of the world. Its interaction with mycorrhiza has been rarely studied, and little is known about its mycorrhizal dependency, especially under drought stress. In a glasshouse experiment, we investigated the effect of Arbuscular Mycorrhiza Fungi (AMF) inoculation on growth, evapotranspiration, mineral nutrition and root morphology of five okra cultivars under ample water and drought stress conditions. ‘Khartoumia’, ‘HSD6719’, ‘HSD7058’, ‘Sarah’ and ‘Clemson Spineless’-cultivars commonly used by farmers in Sudan were chosen for their geographical, morphological and breeding background variations. The plants were either inoculated with R. irregulare or mock-inoculated. Seven weeks after seeding, the soil–water content was either maintained at 20% w/w or reduced to 10% w/w to impose drought stress. Drought stress resulted in plant P deficiency and decreased shoot dry biomass (DB), especially in HSD7058 and Clemson Spineless (69% and 56% decrease in shoot DB, in the respective cultivars). Plant inoculation with AMF greatly enhanced the shoot total content of P and the total DB in all treatments. The mycorrhizal dependency (MD) -the degree of total plant DB change associated with AM colonization- differed among the cultivars, irrespective of the irrigation treatment. Key determinants of MD were the root phenotype traits. Khartoumia (with the highest MD) had the lowest root DB, root-to-shoot ratio, and specific root length (SRL). Meanwhile, HSD6719 (with the lowest MD) had the highest respective root traits. Moreover, our data suggest a relationship between breeding background and MD. The improved cultivar Khartoumia showed the highest MD compared with the wild-type Sarah and the HSD7058 and HSD6719 landraces (higher MD by 46%, 17% and 32%, respectively). Interestingly, the drought-affected HSD7058 and Clemson Spineless exhibited higher MD (by 27% and 15%, respectively) under water-deficiency compared to ample water conditions. In conclusion, the mediation of drought stress in the okra plant species by AMF inoculation is cultivar dependent. The presence of AMF propagules in the field soil might be important for increasing yield production of high MD and drought susceptible cultivars, especially under drought/low P environments.

Intraspecific variation in mycorrhizal response is much larger than ecological literature suggests

“…The range of MGR across 95 native and invasive Northern Plains plant taxa was 5.60 when tested in similar environmental conditions using multispecies inoculum (Reinhart et al, 2017). Although these ranges were larger than most studies assessing intraspecific variation in MGR, three studies had larger intraspecific variation in MGR than the database containing 348 species from across the globe grown in variable conditions, and four studies had larger intraspecific variation than interspecific variation among 69 species found in a single ecosystem grown in the same environmental conditions (Eltigani et al, 2022; Tawaraya et al, 2001; Vestberg, 1992).…”

“…The median range of MGR within a species was 0.90. The three publications with the largest amount of intraspecific trait variation for MGR (Eltigani et al, 2022; Tawaraya et al, 2001; Vestberg, 1992) included genotypes that were highly responsive to mycorrhizal fungi and genotypes that were not, despite the fact that these contrasts included genotype selections that were not highly representative of the genetic diversity within the plant species. Of the 60 experimental contrasts, 36 had plant genotypes with a positive MGR as well as genotypes with a negative MGR in the same environment.…”

“…MycoDB (Chaudhary et al, 2016) and Reinhart et al (2017) show the interspecific diversity in MGR across the plant kingdom and in prairie species respectively. Three studies had larger variation in MGR than the database containing 348 species from across the globe grown in variable conditions and four studies had larger variation than 69 species found in a single ecosystem grown in the same environmental conditions (Eltigani et al, 2022;Tawaraya et al, 2001;Vestberg, 1992). The boxes represent the first and third quartiles and the whiskers extend to the highest and lowest values.…”

Effects of Arbuscular Mycorrhizal Fungi on Growth and Nutrient Accumulation of Oat under Drought Conditions

“…In this study, AMF inoculation resulted in lower N concentrations in oats compared to those without inoculation. It might be the high biomass that led to N dilution in the shoot tissues [43]. However, under water stress, AMF inoculation may promote N uptake by the roots and maintain the stability of the shoot N concentration.…”

Efficacy of Black Cumin (Nigella sativa) Ameliorate Organophosphate Toxicity in Pregnant Rats Based on Progesterone Levels and Fetal Bone Development

“…A total of 6 mL sample of blood serum from albino rats was analyzed for progesterone using an ELISA kit after undergoing various treatments. Then, an ELISA kit was used (E-OSEL-R0007) to determine the progesterone levels in the animals (Eltigani et al, 2021).…”