The study investigated the effects of synthetic and organic fertilizer applications on silage quality and micromorphological characteristics of silage maize in Antalya ecological conditions in 2022. According to Table 1, 2 and 3, fertilizer types significantly influenced Acid Detergent Insoluble Fiber (ADF), Neutral Detergent Insoluble Fiber (NDF), Acid Detergent Insoluble Lignin (ADL), Silage Dry Matter Content (SDMR), stomatal length, stomata number, upper leaf surface epidermis, lower leaf surface epidermis and stomatal length (p<0.01). Cuticle thickness, stomata width and lower leaf epidermis length were also significant (p<0.05). Other micromorphological features measured were not statistically significant.
Fertilizer effects on NDF (%) varied: vermicompost had the highest at 57.31±0.02%, while Synthetic Fertilizer-2 had the lowest at 38.90±0.10%. All fertilizer types formed distinct groups (Table 1). ADF values ranged from 30.55±0.01% for vermicompost to 20.11±0.06% for Synthetic Fertilizer-2. ADL mean values ranged from 3.44±0.04% for Cattle Manure to 2.06±0.01% for Synthetic Fertilizer-2. Silage dry matter varied from 27.69±0.02% for Poultry Fertilizer to 22.19±0.02% for the Control group (Table 1).
Fertilizer treatments showed no significant difference in cuticle thickness (µm): Control group, 4.32±0.41 µm; Synthetic Fertilizer-1, 4.17±0.67 µm; Synthetic Fertilizer-2, 4.20±0.70 µm; Poultry Manure, 5.61±0.80 µm; Cattle Manure, 5.74±0.77 µm; Vermicompost, 5.19±0.48 µm (Table 2). Stomatal cell width (µm) on the upper surface remained consistent across treatments: Control, 8.83±0.77 µm; Synthetic Manure-1, 8.95±0.72 µm; Synthetic Manure-2, 8.69±0.35 µm; Poultry Manure, 10.12±0.87 µm; Cattle Manure, 10.06±0.29 µm; Vermicompost, 8.81±0.93 µm (Table 2). Stomatal length (µm) on the upper surface varied from 46.76±1.57 to 37.83±2.44 µm (Table 2), with Synthetic Fertilizer-2 having the highest and Vermicompost the lowest values. Synthetic Fertilizer-2, Poultry Manure and Synthetic Fertilizer-1 did not differ significantly, while Vermicompost was grouped with Control and Cattle Manure.
When examining the effects of treatments on the number of stomata on the upper surface, mean values ranged from 98.33±10.41 to 58.33±2.89 µm, with the highest value obtained from Cattle Manure. Fertilizer types grouped similarly were Poultry Manure, Vermicompost, Synthetic Fertilizer-1 and Control, respectively (Table 2). Mean values of the number of epidermis on the upper surface varied from 351.67±11.55 to 265.00±26.46 µm, with Cattle Manure having the highest and Synthetic Fertilizer-2 the lowest values. Vermicompost and Synthetic Fertilizer-1 did not differ significantly from Cattle Manure (Table 2).
Epidermis width on the upper surface was not statistically significant across treatments. Mean values were as follows: Control, 34.82±1.63 µm; Synthetic Fertilizer-1, 30.73±1.24 µm; Synthetic Fertilizer-2, 32.49±1.42 µm; Poultry Manure, 28.82±1.95 µm; Cattle Manure, 31.85±3.27 µm; Vermicompost, 33.60±4.93 µm (Table 2). Similarly, epidermis length on the upper surface was not statistically significant across treatments. Mean values were: Control, 106.36±20.47 µm; Synthetic Fertilizer-1, 110.84±10.11 µm; Synthetic Fertilizer-2, 116.52±6.52 µm; Poultry Manure, 111.05±11.10 µm; Cattle Manure, 91.60±14.12 µm; Vermicompost, 97.29±4.89 µm (Table 2). Stomatal index on the upper surface was also found to be statistically insignificant across treatments, with mean values ranging from 23.95±3.63 to 18.24±1.07 SI (Table 2).
Glandular hairs were observed on the lower leaf surface with deeper periclinal and anticlinal walls. Comparing lower leaf epidermal cell widths, the smallest was in Synthetic Fertilizer-1 and the largest in Synthetic Fertilizer-2. The longest epidermal cells were in Synthetic Fertilizer-2 and the shortest in Poultry Manure treatments. Stomatal width decreased in Poultry Manure and Vermicompost treatments compared to the control, with the lowest stomatal length in the vermicompost treatment. Stomatal density was highest in Cattle Manure and lowest in Synthetic Manure-1 and -2 treatments. Stomatal index was higher in Poultry Manure treatment than others (Table 3, Fig 2 and 3).
This study investigated the effects of different organic and synthetic fertilizers on silage quality and leaf micromorphological characteristics of silage maize. NDF (Neutral Detergent Insoluble Fiber) is vital for silage quality, ideally below 40%. Synthetic Fertilizer-2 was most effective in reducing the NDF ratio, followed by Synthetic Fertilizer-1. Our findings ranged from 57.31% to 38.9%, with vermicompost showing the highest ratio. Synthetic fertilizers, widely used in cultivated plant cultivation, provide plants with nutrients rapidly. Their chemical content is more concentrated compared to other organic fertilizers, facilitating high plant uptake (
Karaşahin, 2022).
In this study, synthetic fertilizers were observed to enhance plant productivity and quality, particularly in reducing NDF levels. Comparable findings were reported in previous studies examining NDF ratios in corn for silage
(Zhao et al., 2022; Koenig et al., 2023; Chayanont et al., 2021; Liu et al., 2021; Karydogianni et al., 2022). However, some studies reported higher NDF ratios
(Behrouzi et al., 2022; Amasaib et al., 2022; Cai et al., 2020), likely due to variations in fertilizer content.
For quality forage, ADF ratios should ideally be around 30% or lower (Keleş and Çýbýk, 2014). Synthetic Fertilizer-1 yielded the best quality results in our study, followed by Synthetic Fertilizer-2, indicating their superior effectiveness compared to organic fertilizers. Vermicompost exhibited the poorest silage quality, with the highest ADF ratio, while cattle and poultry manure resulted in the lowest quality silage. Our results ranged from 30.55% to 20.11%, aligning with some previous studies
(Zhao et al., 2022; Ma et al., 2023; Koenig et al., 2023; Chayanont et al., 2021; Liu et al., 2021), but differing from others
(Behrouzi et al., 2022; Amasaib et al., 2022; Cai et al., 2020).
For silage quality, parameters like ADF (Acid Detergent Insoluble Fiber), NDF (Neutral Detergent Insoluble Fiber) and ADL (Acid Detergent Insoluble Lignin) are crucial, as they are digestible by animals. Lignin, providing rigidity to cell walls, increases as plants age and is indigestible by animal enzymes. Hence, a low ADL value is desirable in silage materials
(Meltem et al., 2013). Our study yielded ADL values ranging from 3.35% to 2.06%. Synthetic Fertilizer-2 performed best in ADL ratio, followed by Synthetic Fertilizer-1, while the lowest result was from Cattle Manure. These results were consistent with other quality parameters (NDF and ADF), indicating synthetic fertilizers’ superior efficiency over control and organic fertilizers. Similar studies showed ADL results of 3.99-3.39%
(Koenig et al., 2023), 3.60-2.92%
(Chayanont et al., 2021), 3.14%
(Liu et al., 2021) and 3.49±0.54%
(Cai et al., 2020), supporting our findings.
Silage dry matter rate is another critical factor in silage maize. Vermicompost, followed by cattle and poultry manure, were the most effective fertilizers on silage dry matter, outperforming synthetic fertilizers and control treatment. Organic fertilizers, containing fewer chemicals, are generally less harmful to living tissue (
Korkmaz and Akýncý, 2023). This suggests organic fertilizer varieties’ effectiveness over synthetic ones, especially in increasing dry matter and its accumulation in the plant. In our study, the silage dry matter rate ranged from 25.61% to 24.11%, lower than results from similar studies such as 29.37%
(Liu et al., 2021) and 28.14%
(Korkmaz et al., 2019).
In several Zea mays studies, leaf epidermis, silica cell structure and stomatal characters were explored
(Driscoll et al., 2006; Gao et al., 2006; Suriyaprabha et al., 2012). Light and scanning electron microscopy showed smaller stomatal dimensions in vermicompost-treated Zea mays leaves. The highest stomatal index occurred in Poultry Manure-treated leaves. Many small stomata are associated with higher photosynthesis rates
(Suriyaprabha et al., 2012; Drake et al., 2012). Poultry and vermicompost treatments promoted plant growth. Fertilizer applications affected cuticle thickness, epidermis and stomatal properties. Stomata play crucial roles in photosynthesis and gas exchange. Stomatal size varies by environmental conditions (
Pekşen et al., 2006). Stomatal size differs among species and cultivars (
Budaklý and Çelik, 2013).