Introduction: Malva sylvestris, commonly known as the common mallow, is a flowering plant species in the genus Malva. It is native to Europe, North Africa, and Western Asia, and has been introduced to other parts of the world. The plant has been known since ancient times and is considered the "type-species" for the genus. The leaves are edible and the plant (and seeds) are used as herbal remedies. Malva sylvestris is either a perennial or biennial plant. It spreads readily from seed and can self-seed prolifically. The seeds resemble small wheels or discs. The plant is known to be susceptible to a virus called Malva vein clearing potyvirus, which is transmitted by aphids. It also contains compounds such as malvin, malonylmalvin, and the naphthoquinone malvone A. The aim of this article is to evaluate the various (nine) ecotypes of Iranian Malva sylvestris L. by analyzing their morphological and physiological characteristics. By employing a step-by-step regression approach, the study seeks to identify significant traits that differentiate these ecotypes. The research intends to enhance understanding of the adaptive strategies of Malva sylvestris in diverse environmental conditions. Ultimately, the findings aim to contribute valuable insights for conservation efforts and the potential use of these ecotypes in horticulture and agriculture. This comprehensive evaluation will also provide a foundation for future studies on the species' ecological adaptability.
Materials and Methods: In this study, 9 ecotypes of Malva sylvestris were collected in 2017 from different habitats in Iran (Mashhad, Torbat-e Heydariyeh, Fariman, Zabol, Zarand, Jiroft, Rudbar, Bandar Abbas and Khorramdasht) (Table 1) and identified in the Herbarium of Torbat-e Heydariyeh University. They were then cultivated in a completely randomized design with three replications in late February 2018 in the greenhouse of the Agricultural Research Institute of the University of Zabol and evaluated in May 2019. The seeds of each ecotype were planted in 5-liter pots (after germination and thinning, five plants of each ecotype were kept in each pot) in a growing medium consisting of an equal mixture of agricultural soil, coco peat, perlite, and well-rotted animal manure. Irrigation was calculated based on the temperature conditions in Sistan and the greenhouse, as well as the field capacity of the pot mixture, and was carried out regularly until flowering. At full flowering, the stem diameter and length of three plants from each pot were randomly measured and their means were considered for each treatment. At this stage, the number of flowers with seeds and the number of leaves of each plant were counted. Fresh and dry weights of root, stem and whole plant were measured with a digital scale (0.01 g accuracy). For dry weight measurement, fresh samples were placed in an oven at 70°C for 48 hours. Chlorophyll a, chlorophyll b and carotenoid contents were determined. The absorbance of the samples for chlorophyll a and b and carotenoids was measured at wavelengths of 663, 645 and 470 nm, respectively, using a spectrophotometer. Proline, soluble carbohydrates, and protein were measured. Pearson correlation coefficients were used to calculate simple correlation coefficients between morphological traits. Statistical analysis of traits was performed using SAS Ver. 9 and Excel software, and means were compared by Duncan's method at 1% and 5% probability levels.
Results and Discussion: The highest stem diameter (9.58 mm), root length (61.22 cm), root weight (18.86 g), root dry weight (4.84 g), and proline content (0.614) belonged to Mashhad ecotype. The number of leaves had a negative and significant correlation with the fresh weight of the plant, while it had a positive and significant correlation with plant height and shoot dry weight. Other traits did not show a significant correlation with the number of leaves per plant. The highest correlation was observed between morphological traits between fresh weight and leaf dry weight (P<0.01) and in phytochemical traits between carotenoid and chlorophyll b (P<0.05). Based on stepwise regression in the presented models, root weight and plant dry weight had the most positive effect on root length, but stem diameter and plant weight had the most negative effect. Chlorophyll b had the most negative and direct effect on proline yield, but chlorophyll a, carotenoids, carbohydrates, and total protein had the most positive effects, respectively. The variance analysis results indicated significant differences among the various ecotypes of Malva sylvestris regarding morphological and phytochemical traits (P<0.01) (Tables 2 and 3). Mean comparisons revealed that the Mashhad ecotype excelled in stem diameter, root length, and fresh and dry root weight, while the Rudbar ecotype showed the highest fresh weight in aerial parts. The Bandar Abbas ecotype had superior fresh and dry weights of aerial parts, leaf count, flower count, and seed count, and the Torbat-e Heydariyeh ecotype was notable for flower and seed counts per plant (Table 4). The tallest stem (40.55 cm) was recorded in the Jiroft ecotype, while the shortest (1.81 cm) was from Mashhad. The greatest stem diameter (9.58 mm) belonged to the Mashhad ecotype, and the smallest (3.54 mm) was found in Zabol. Root length also varied, with the Mashhad ecotype having the longest (61.22 cm) and Rudbar the shortest (9.55 cm) (Table 4). The highest fresh and dry root weights were observed in the Mashhad ecotype, while the Jiroft ecotype had the lowest.
Conclusion: In the results of step-wise correlation and regression analysis of the medicinal plant Malva sylvestris L., the highest positive regression coefficients for yield were related to the traits of proline content, root fresh weight, and plant dry weight, which indicates their more fundamental role in increasing yield and their potential for improvement. Overall, the present study showed that root-related traits had an important effect on the final yield in the Mashhad population of Malva sylvestris L., and the Mashhad ecotype also showed the most desirable performance in terms of the evaluated traits. Due to its high performance in these traits, the Mashhad ecotype is recommended for researchers, universities, and private sectors involved in the cultivation and domestication of medicinal plants.