*3.9. In Vivo Antifungal Efficacy*

The control plants exhibited a disease severity (DS) of 42.9 ± 3.3% for early blight and 40.9 ± 0.8% for leaf spot disease after seven days of conidial spraying of a pathogenic fungus, as shown in Table 4. Disease control efficiency (DCE, in percent) in pathogen-treated plants for loaded NPs was found to be 66.2 ± 5.0% and 70.7 ± 1.6%, respectively, against early blight and leaf spot diseases, which is comparable to sick pathogen plants treated with commercial fungicide (66.0 ± 3.5% and 68.5 ± 1.1%) (Table 4). Similar to metolachlor alone, polymeric (PEG-PLGA) nanoparticles loaded with the weed killer metolachlor showed strong herbicidal action against *Digitaria sanguinalis*, *Oryza sativa,* and *Arabidopsis thaliana* in the research [44].

**Table 4.** Treatment effects of CSGA NPs on percentage disease severity (DS) and disease control efficacy (DCE) in tomato plants under pot house conditions against early blight and leaf spots.


Each value is a mean of a triplicate. Mean ± standard deviation followed by the same letter in the treatment column indicate that values are not significantly different at *p* ≤ 0.05, as determined by a *t*-test.

In the pot settings, chitosan nanoparticles, and chitosan–silver nanocomposites were as efficient as traditional fungicides, such as copper oxychloride 525]. Another study used silver nanoparticles produced by rhizospheric chickpea microorganisms to treat chickpea wilt illness in vivo (*Cicer arietinum*). The current investigation of disease inhibition is in line with earlier research [15]. Earlier, applying chitosan hexaconazole–dazomet to treat *G. boninense*-caused basal stem rot disease in palm trees reduced the disease by 74.5% [45]. These findings corroborate the validity of the current research.

## *3.10. Plant Growth Parameters Study*

For this study, three parameters, namely germination percentage, dry mass per plant, and root-shoot ratio, were chosen for the pot house conditions.

#### 3.10.1. Effect of Treatment on Germination Percentage

The tomato is an important crop sown globally. No comprehensive research data are available on the effects of chitosan–gum acacia nanoparticles on plant germination indices in pot or field conditions. The lowest germination (60%, in both) was observed in plants treated with fungicide alone (F) and plants treated with blank NPs, which were made sick with the pathogen *A. alternata* (N1P1). The highest germination (78%) was recorded in plants treated with *S. lycopersici* and loaded NPs (N1FP2). It was pretty high as compared to plants treated with commercial mancozeb alone (F-60%), plants treated with pathogen *S. lycopersici* alone (CP2-72%), and fungicide-treated plants, which were made sick with *S. lycopersici* (FP2-62%). From the above data, it can be conferred that the loaded NPs (N1FP2) treated with *S. lycopersici* showed good germination (78%) compared to commercial mancozeb (60%). The same pattern of germination in the present study was found in earlier research, where the germination of the seeds treated with nanoformulation was 96%, while pure carbendazim showed decreased (60%) germination [23].

#### 3.10.2. Tomato Dry Mass per Plant

The highest mass of 1328.3 mg was obtained for plants treated with fungicide-loaded NPs, and made sick with *S. lycopersici* (N1FP2), followed by 1102.5 mg for fungicide-treated plants made sick with *S. lycopersici* (FP2). Plants treated with fungicide alone (F) had a mass of 630 mg, which is relatively lower than all the NP-treated plants. Hence, all treatments, except N1P1 (plants treated with blank NPs, and made sick with *A. alternata*), had a positive effect on the plant biomass or weight per plant compared to the fungicide alone at a concentration of 10 ppm of foliar spray of NPs with 1.0 mg/mL of mancozeb, i.e., CSGA-1.0. In an earlier study, high concentrations of ZnO and silver NPs harshly affected the growth of tomato and wheat plants, respectively [46,47]. Earlier research also found that root and shoot growths in tomatoes were more affected by silver usage than seed germination [48].

#### 3.10.3. Root–Shoot Ratio of Plants

The most significant shoot lengths of 19.5 and 19 cm were observed in plants treated with mancozeb-loaded nanocomposites infected with *A. alternata* and *S. lycopersici,* respectively. There may be some interactions between mancozeb-loaded NPs and pathogens, which caused an increase in shoot length. In a study, CeO2 NPs were found in soybean roots and root nodules after growth in soil treated with NPs [49]. A similar transfer in corn plants was found, and CeO2 NPs around vascular vessels supported that the particles found their way to the transportation system and moved through the xylem compelled by transpiration [50]. The most miniature shoots (11 cm) were seen in control plants, commercial fungicide-treated plants, followed by plants treated with blank and loaded nanocomposites (11.5 cm). The most significant root length (15.3 cm) was found in plants treated with commercial mancozeb and infected with *A. alternata* while the smallest root length of 8.0 cm was observed in control plants. So it can be concluded that nanocomposites positively affected the shoot and root lengths of plants compared to non-treated plants.
