The Influence of Glomus Mosseae, Palm Frond Compost and Irrigation Duration on the Growth of Millet Plant (Panicum miliaceum L.) and on the Availability of Iron and Zinc in the Soil

To study the effect of inoculation with Gloums Mosseae inoculum, organic residues (palm fronds compost), and irrigation duration on the growth and availability of iron and zinc for millet plant Pamicum Miliaceum L., a field trial was carried out for the summer season 2022 in one of the fields of Al-Diwaniyah Governorate - Sumer district in sandy clay loamy soil. The experiment was implemented following a Randomized Complete Block Design (RCBD) with three replications. The experimental treatments were distributed randomly. They were: with and without fungal inoculum (F0 and F1), three levels of organic residue applications C0 = control, C1 = 3 tons of compost application, C2 = 5 tons of compost application, and three irrigation durations R1= Irrigation every 10 days, R2 = irrigation every 15 days, R3 = irrigation every 20 days. The results are summarized as follows: The results present a significant increase in all the studied traits, plant height, shoot dry weight, and iron concentration in the soil during the flowering and full maturity stages, except for the zinc concentration in the soil, which the increase was not significant. The values of these traits were 88.84 cm plant-1, 56.15 gm plant-1, 290.2 mg Fe kg soil-1, and 230.9 mg Fe kg soil-1, respectively, compared to the control treatment (no application + irrigating every twenty days) 50.62 cm plant-1, 23.53 g plant-1, 135.4 mg Fe kg soil-1,120.8 mg Fe kg soil-1.


Introduction
Millet is one of the summer grasses cultivated for grain and forage production.Approximately 70 million hectares are cultivated worldwide, 68.5% in Asia and 22.5% in Africa [1].Local millet varieties, Proso millet Panicum miliaceum L., are the sixth most economically significant cereal [2].It has a high yield of green forage and a high ratio of leaves to stems, and its stems contain a high proportion of protein and sugar, making it a highly nutritious crop [3].Bio inoculants supplement chemical fertilizers, which have acquired prominence over the past few decades, and play a crucial role in maintaining soil fertility and sustainability.Environmentally safe and inexpensive, vital inoculants are a continuous source of essential nutrients for plant growth [4].Mycorrhiza fungi exist symbiotically with the roots of numerous plants in the soil.This variety of fungi has significant environmental and physiological benefits for infected plants, so symbiotic living has captivated the interest of numerous researchers.It plays a significant function in 1259 (2023) 012018 IOP Publishing doi:10.1088/1755-1315/1259/1/012018 2 plant nutrition by enhancing the plant host's assimilation of most macro-and micronutrients [5,6].The Glomus Mossea can provide approximately 50% of the plant's phosphorus, 25% nitrogen, and 10% potassium requirements [5].The fungus and plant share a symbiotic relationship, with the fungus providing macro-and microelements to the plant and protecting it from soil-borne pathogens.It also contributes to a plant's resistance to stress and drought [7].Some researchers characterize compost as plant residues that microscopic soil organisms have decomposed into organic fertilizer.It is an organic fertilizer with plant residues like fallen leaves, roots, and stalks.Carbon, nitrogen, hydrogen, phosphorus, etc., are among the most vital nutrients a plant requires, and compost plays a crucial function in supplying them [8].Due to the severe climatic conditions in arid and semi-arid regions, water is the most critical factor in agricultural development.Water stress plays a role in the natural environmental alterations of plants in general, which is reflected in the disruption of vital physiological processes and a decline in plant productivity [9].Numerous studies demonstrated that water stress causes numerous phenotypic alterations in plants.It reduces plant height, leaf area, and chlorophyll content, decreasing photosynthetic rates [10].Given the paucity of scientific research on millet, this study aimed to determine the effect of inoculum with the Glomus Mosseae fungus and palm frond compost on the growth and availability of iron and zinc in millet plant Panicum miliaceum L. under various irrigation durations.

Materials and Methods
In one of the farms of Al-Diwaniyah Governorate in the district of Sumer, to the north-east of the city, sandy clay loamy soil was used to cultivate a local variety of millet (Panicum miliaceum L) during the summer season of 2021-2022.Before beginning the fieldwork, the land was thoroughly prepared by adjusting and stabilizing it and clearing it of shrubs and plants.To acquire a homogeneous soil sample to analyze the physical, chemical, and biological characteristics of the pre-planting soil, multiple soil samples were collected randomly from various locations in the field.The soil's physical and chemicalbiological properties were evaluated after the sample was air-dried and sieved through a 2-millimeter mesh.Mycorrhiza inoculum (spores + desiccated soil + infected roots) was utilized.The experiment's fungal inoculum was acquired in collaboration with the Agricultural Research Department_Ministry of Science and Technology_AL-Zaffronia. Before sowing, the inoculum (spores, infected roots, soil) was applied to the plates and disseminated over the field area with a 5 cm depth below the seeds.

Experimental design and treatments distribution
The experiment was designed using the Randomized Complete Block Design (RCBD) with three replications with 54 experimental units, and each of the three sectors included 18 treatments, and the treatments were distributed randomly in the field.The area of the experimental unit is 6 square meters, its dimensions are 2×3, and an isolation distance was left between the sectors of 2 meters, and an isolation distance between the experimental units was 1 meter, and a distance of 2 meters was left on both sides of the field.The experimental treatments were as follows: fungus inoculation treatment F (F0 no inoculation, F1 inoculum application) and the compost treatment C (C0 no application, C1 application of 3 tons ha, and C2 application of 5 tons ha) and treatment irrigation duration R ( R1 irrigate every 10 days, R2 irrigate every 15 days, an R3 irrigate every 20 days).

Plant Height (cm plant -1 )
The plant height was measured for five random plants from each experimental unit at the end of the season, and it was measured using a measuring tape from the soil surface level to the highest peak of the plant, and then the average was extracted for it.

The Dry Weight of Shoots (gm plant -1 )
Five plants were taken from each experimental unit at the end of the season.The plant was extracted entirely and accurately, the vegetative system was cut only and placed in paper bags, and the relevant transactions were written on them.They were dried in the oven at 60 °C until the weight stabilized, then the dry shoots were calculated using a sensitive scale.Soil content of iron and zinc for the two times of flowering and the end of the season (Fe and Zn mg L -1 ): The estimate was made using the atomic absorption spectrophotometer according to the method [4].
Table 1.The field soil's physical, chemical and biological characteristics (before planting).

The Effect of Applying G.mosseae, Compost, and Irrigation Duration on Plant Height
The results of Table (2) indicated a significant increase in the height of the millet plant when inoculated with the fungus, and the average values of the inoculation treatment were 70.92 cm plant -1 compared to the control treatment of 64.23 cm plant -1 .The reason for this is due to the positive effect of inoculation with the G.mosseae because it helps the infected roots to take nutrients beneficial to the plant, which creates a balance in the plant's nutrition, and this is reflected positively in the growth characteristics of the plant, including the characteristic of the plant's height, which is consistent with [11].
The compost achieved a significant effect and the treatment C1 increased the values significantly by 73.20 cm plant -1 compared to the control treatment C0 59.11 cm plant -1 .This is due to the role of compost in increasing the availability of nutrients in the soil and increasing the absorption of nutrients from them, especially P and N, which contribute to the synthesis of nutrients [12].Table 2 also presents the effect of irrigation duration, which significantly influenced plant height.Irrigation treatment every ten days produced the highest value of an average of 74.15 cm plant -1 compared to the irrigation duration every fifteen days 70.08 cm plant -1 and the irrigation duration every twenty days, 58.50 cm plant -1 .The reason for the decrease in the height of the plant is attributed to the fact that the long duration of irrigation caused a decrease in the growth of the roots, and thus the ability of the plant to absorb water decreased, and thus the vital activities in the vegetative system decreased, leading to a decrease in the level of growth characteristic of the plant height.
The bilateral interaction between irrigation and fungus duration significantly affected the height of the millet plant, and treatment F1R1 (inoculation with fungus + irrigation every ten days) resulted in the highest value of interaction 78.68 cm plant -1 compared to control treatment F0R3 56.04 cm plant -1 .
The reason is attributed to the fact that the bio-inoculum with seeds leads to an increase in the concentration of the inoculum in the root periphery, and thus increases the chance of occupation and colonization of the roots, and thus the microbe can benefit from the root secretions.This is consistent with the results of [13] for the wheat crop.
As for the dual interaction between irrigation duration and organic compost, it had a significant effect on plant height.Treatment C1R1 (compost 3 tons + irrigation every 10 days) resulted in the highest interference values of 80.65 cm plant -1 compared to treatment C0R3 (no compost application + irrigation every twenty days) 50.71 cm plant -1 .Also, the binary interaction between fungus and compost significantly affected plant height.The F1C1 treatment was associated with the most significant overlap of 80.18 cm plant-1 compared to the treatment (F0C0), resulting in an overlap of 55.76 cm plant -1 .
The triple interaction between the study factors was significant in plant height, as the treatment F1C1R1 resulted in the highest Value of overlap, 88.84 cm plant -

Effect of G.mosseae Application, Compost, and Irrigation Duration on the Dry Weight of Shoots
Table 3 presents that inoculation with G.mosseae resulted in a significant increase in the dry weight of shoots of the millet plant.The inoculated treatment yielded 42.51 g plant -1 compared to the control 37.49 g plant -1 .The reason is attributed to the role played by the fungus in increasing the accumulation of dry matter in the vegetative part, as well as its ability to absorb essential nutrients, improve water relations, and increase the surface area of the root.The compost had a significant effect, as the treatment C1 valued 43.93 g plant -¹ , which was significantly superior, while the control treatment made 33.26 g plant -¹.This is due to organic fertilizers' direct or indirect role in plant growth.The direct role is represented by increasing nutrients' availability, release, and absorption.In contrast, the indirect role is represented by the fact that it improves the soil's physical, chemical and biological properties by increasing the activity of microorganisms and soil water retention.This increases root penetration and thus increases the amount of nutrients absorbed.All of these factors affect the increase in the shoot's dry weight, which is consistent with [14].
The irrigation duration had a significant effect on the dry weight of shoots.For example, the irrigation duration every ten days resulted in values of 45.06 g plant -1 weight, compared to the fifteen-day irrigation duration that resulted in 44.18 g plant -1 , and the twenty-day irrigation duration of 30.92 g plant -1 .The reason is attributed to the deficiency caused by changing the irrigation duration, which leads to a lack of water, which in turn leads to a decrease in root growth, which results in a decrease in the vegetation of the millet plant, which was explained by [15].The dual interaction between irrigation duration and fungus inoculum was significant for dry shoot weight.For example, treatment F1R1 resulted in the highest interference value of 48.40 g plant -1 compared to the control treatment F0R3 which gave the lowest interference value of 28.60 g plant -1  because the inoculum leads to an increase in the processing capacity of essential nutrients, which leads to an increase in the synthesis of carbohydrates and amino acids.This increases the demand for nitrogen, and this helps synthesize proteins necessary for the growth of new cells [16].
The triple interaction between the study factors was also significant in the dry weight of shoots.Treatment F1C1R1 resulted in the highest interference value of 56.15 g plant -1, and the control treatment F0C0R3 resulted in the lowest interference value of 23.53 g plant -1 .4 and 5 show that fungal inoculation significantly affected plant growth parameters.The values increased significantly with the F1 treatment, whose average was 0.995 and 0.860 mg Fe kg soil -1, compared with the values of the F0 treatment, 0.886 and 0.739 mg Fe kg soil -1 .The reason for this is that the G.mosseae fungus works to increase the availability of the elements and convert them from the compound form into an available form, and this is consistent with the results [17] , also, the ability to secrete clonidine increased, which in turn works to hold soil particles by forming large aggregates, and this improves the ability of the soil to retain the necessary elements and water and increase their concentration in the root depletion zone, and this agrees with [18].The Table also shows that organic fertilization with compost had a significant effect and that the treatment C1 resulted in average values of 1.059 and 0.916 mg Fe in kg soil-1, while the control treatment C0 had an average of 0.726 and 0.601 mg Fe in kg soil -1 .This is due to the role of organic fertilizers in forming complex compounds with iron that limit the adsorption and sedimentation of iron and thus increase its availability in the soil [19].
As for the irrigation duration, they significantly affected the soil content of available iron.The irrigation duration every ten days resulted in the highest value in flowering and full maturity stages, its values were 1.070 and 0.914 mg Fe in kg soil -1 .On the other hand, the irrigation duration every fifteen days produced an average of (1.052 and 0.900) mg Fe kg ¹-soil, and the lowest value was under the irrigation duration every twenty days with an average of 0.699 and 0.585 mg Fe kg soil -1 .The reason for this is attributed to the decrease in the necessary elements required for the plant due to water stress due to the long duration of irrigation, which reduces the movement of nutrients and thus reduces the ability of the plant to absorb them [20].
The dual interaction between irrigation duration and fungus was significant in soil iron content during flowering and maturity.Treatment F1R1 resulted in the highest interference value of 1.151 and 0.994 mg Fe kg -1 compared to control treatment F0I10 which resulted in the lowest value of 9.89 mg Fe kg -1 .
The reason is due to the ability of the fungal and bacterial bio-inoculums to supply macro and microelements as well as to increase the tolerance of the plants to water stress and to improve soil structure [21].
The bilateral overlap between irrigation duration and compost application was significant with treatment C1R1, which resulted in the highest value between treatments in the two durations, 1.215 and 1.048 mg Fe kg -1, and the values of treatment C1R2 were 1.187 and 1.034 mg Fe kg -1 compared to treatment C0R3 that resulted in the lowest value for overlap 0.512 and 0.409 for Mg Fe kg -1  The triple interaction resulted in a significant effect by the treatment F1C1R1 1.267 and 1.110 mg Fe kg soil -1 , while the control treatment F0C0R1 0.443 and 0.348 mg Fe kg soil -1 .Tables (4 and 5): The effect of applying G.mosseae inoculum, compost, and irrigation duration on the iron element at flowering and full maturity stages.The effect of applying G.mosseae, compost, and irrigation duration on the elemental zinc at flowering and full maturity stages (mg Zn kg -1 ).The results of Tables 6 and 7 present that the application of G. mosseae did not significantly affect the soil zinc content and the duration of flowering and full maturity, as well as the bilateral and triple interactions between the studied factors were not significant either.Tables (6 and 7): The effect of applying G.mosseae, compost, and irrigation duration on the zinc element at the flowering and full maturity stages.

Table 2 .
1, compared to the control treatment F0C0R1 resulted in the lowest Value of overlap, 50.62 cm plant -1 .Effect of G.mosseae inoculation, compost, and irrigation duration on plant height.

Table 3 .
Effect of G.mosseae application, compost, and irrigation duration on the dry weight of shoots.

Table 5 .
Soil iron concentration -full maturity stage.

Table 7 .
Soil Zinc concentration -full maturity stage.