Effect of Using The Entomopathogenic/Endophytic Fungus, Beauvaria bassiana on Quality of Sweet Potato Crop and Associated Insects Under Sohag Governorate Conditions

This work was conducted during two successive seasons (2018 and 2019) at the experimental research station, Shandweel, Sohag, Egypt to study the effectiveness addition methods of the fungus, Beauvariabassiana on growth, yield quality and some of the chemical constituents, moreover, associated insects and their damages to vegetative and storage roots growth were calculated of sweet potato plants growing under Sohag governorate conditions. The obtained results indicated that the different addition treatments of B. bassiana wereshowed an increase in growth traits when the plants were sprying twice by B . bassiana given the highest values of plant length, fresh weight compared with other treatments studied in both seasons. The gained results of yield and its contents included that addition of B.bassiana in soil twice gave the best values of total yield, marketable yield, theaverage weight of storage roots as well as highest dry matter percentage of storage roots compared with other treatments, at the same time the control treatment showed the lowest of values of all studied traits in both seasons. Soil application of B . bassiana twice was affected significantly on chemical constituents of sweet potato storage roots (nitrogen%, phosphorus%, potassium%, Protein% and starch%) except potassium% and starch in the first season. Twice foliar application of fungus was the most effective application on leave defoliators and recorded the lowest number of whiteflies.

This work was conducted during two successive seasons (2018 and 2019) at the experimental research station, Shandweel, Sohag, Egypt to study the effectiveness addition methods of the fungus, Beauvariabassiana on growth, yield quality and some of the chemical constituents, moreover, associated insects and their damages to vegetative and storage roots growth were calculated of sweet potato plants growing under Sohag governorate conditions. The obtained results indicated that the different addition treatments of B. bassiana wereshowed an increase in growth traits when the plants were sprying twice by B. bassiana given the highest values of plant length, fresh weight compared with other treatments studied in both seasons. The gained results of yield and its contents included that addition of B.bassianain soil twice gave the best values of total yield, marketable yield, theaverage weight of storage roots as well as highest dry matter percentage of storage roots compared with other treatments, at the same time the control treatment showed the lowest of values of all studied traits in both seasons. Soil application of B. bassiana twice was affected significantly on chemical constituents of sweet potato storage roots (nitrogen%, phosphorus%, potassium%, Protein% and starch%) except potassium% and starch in the first season. Twice foliar application of fungus was the most effective application on leave defoliators and recorded the lowest number of whiteflies. resulting in multiple applications. With an endophytic establishment, the beneficial fungi can be present continuously in the host plant which is more economic and ecologically friendly. B. bassiana is an important environmentally friendly bio-control agent and its potential to colonize the plants has been widely recognized. In the past decades, many microorganisms have been isolated and investigated for use as a biocontrol agent. Now, many promising strains are available for release into the environment and especially with the renewed interest in biocontrol await further exploitation for large-scale application in agriculture (Glare et al., 2012). Parsa et al. (2013)B.bassiana is a fungal entomopathogen with the ability to colonize plants endophytically. As an endophyte, B. bassiana may play a role in protecting plants from herbivory and disease. Saad and Fathi (2004) Surveys conducted over two successive seasons showed that 20 insect species belonging to orders viz, Homoptera, Lepidoptera, Hemiptera, Orthoptera, Thysanoptera, and Coleoptera attack sweet potato. The homopterans were the dominant insects. The total of beneficial insects associated were thirteen species belonging to six orders viz., Coleoptera, Odonata, Hemiptera, Diptera, Dermaptera, Nuroptera. The early planting date harbored the lowest number of insect species, while the late planting increased the population. The variety NcSu925 (Kafr EI-Zyat) was the most resistant to all groups of insects studied. The aim of this study was to investigate the effect of Bbassiana fungi application on growth, yield and associated insects of sweet potato under Sohaggovernorate conditions.

MATERIALS AND METHODS
This work was carried out at the experimental farm of Shandweel Agricultural Research Station, Sohag Governorate during the two successive summer season, 2018 and 2019 to study the effect of using the entomopathogenic/endophytic fungus, Beauvaria bassiana on the quality of sweet potato crop and associated insects. The initial preparation of the experimental soil is presented in Table (1). The experiment was included 6 treatments (including control treatment) sorted in Randomized Complete Blocks Design with three replicates. Each experimental plot was14 m 2 consists of five ridges each ride having 70 cm width and 4 m in length at 30 cm apart. Transplants were transported on the18 th and 20 th in April seasons 2018 and 2019, respectively.
The fungus, B. bassiana was maintained on PDA, (potato dextrose agar) medium, which PDA containing 200 g/L of potato extract, 20 g/L of glucose, and 20 g/L of agar at pH 7.0 (Yong Jiaet al., 2013). The culture medium was inoculated with agar containing fungal discs and incubated at 28 ± 2 ºC under constant shaking conditions (100 rpm ) in dark for 14 days. Fungal conidia were harvested from 3-week-old PDA cultures. The conidial suspension was prepared in sterile 0.1% Tween 20 solution and the conidia concentration was adjusted to 1×10 8 conidia ml -1 . Six treatments of fungus application were used as follow: 1 All experimental plots were fertilized with 40Kg/fed. (Ammonium nitrate 33.5) with 40Kg of P2O5 fed.(Superphosphate 15.5%) and 72Kg K2O/fed. (Potassium sulfate 48% K2O) were added on two equal parts at three and seven weeks after transplanting. The normal cultural practices have been done as usual for the sweet potato crop.

Recorded Data:
During the two experimental seasons the following data were recorded as follow: Vegetative Character: A month before harvest, five plants were randomly taken from each replicate to determine, the main stem length (cm), the number for branches/plant and weight of vines/plants (Kg), and dry matter (D.M) of vines%.

Yield and Quality:
Sweet potatoes were harvest on the15 th and 19 th in September 2018-2019 seasons, respectively, total yield per plot was recorded and converted to total yield/fed. (ton), marketable yield (ton), number of storage roots/plant) weight of root (g), rootlength (cm), root diameter(cm)and percentage of dry matter (D.M) in storage roots.

Storage Roots Chemical Constituents:
Randomly samples of 5 cured storage roots of sweet potato were taken to determine Nitrogen%, Phosphorus% and Potassium%according to methods described by Kock and McMeekin (1924), Murphy and Rily (1962) and Brown and Lilleland (1946), respectively. Starch content (%) in storage roots was determined using A.O. A.C. (1970).

Insect Examination:
1-The population of aphid and weight fly were calculated fortnightly for all treatments, of which 45 leaves were chosen randomly from each plot and transferred to the laboratory in paper pages. 2-Forty-five leaves of plants were chosen from each plot of the experiment (picked up from top, middle and base of sweet potato plants) in paper bags then transfer to the laboratory to count damage according toKasopers (1965). 3-Fifteen roots were chosen from each plot and the damages were estimated according to Kasopers (1965)  Data were statistically analysis using Complete Blocks Design, and LSD at 0.05 level was used to compare the means of all data of the two seasons as mentioned by Gomaz and Gomaz(1984).

Vegetative Growth Characters:
The endophytic, Beauvaria bassianahad positive effect on sweet potato plants shown Table (2). The highest values of vegetative growth characters, i.e. plant length, the number of branches/plants, fresh weight and dry matter percentage of branches were observed when the plants spraying with B. bassiana twice in both seasons, except dry matter percentage in the second season. On the other hand, the lowest values of these parameters were recorded in the untreated plants by B. bassiana (control) in two successive seasons. The beneficial effect of active B.bassianafoliar application on thegrowth character of sweet potato plants may be due to the effect of B. bassianaon the availability of nutrients in plants . According to Surendraet al., (2017) used B. bassiana to promotes cabbage growth and had a positive influence on survival, growth, health, length, and dry weight. A few studies have shown positive effects on plant growth following the conidial application of entomopathogenic endophytes including higher stand count, root and shoot growth (Ownley et al., 2004(Ownley et al., , 2008Griffin et al., 2005;Kabaluk and Ericsson 2007). Also, B. bassiana promotes plant growth of cassava (Manihot esculenta), faba bean (Vicia faba) and cotton (Gossypium hirsutum) (Lopezand Sword, 2015; Greenfield et al., 2016;Jaber and Enkerli, 2016 a and b).In cotton plants, B. bassiana treatments could induce the length and weight of fresh stem (Mazen et. al., 2020).

Root Yield and Its Components:
In both seasons the results presented in Table (3) show the salary that applications with B.bassiana significantly affected on yield and quality of root parameters in both seasons. The application of.Bassianain the soil twice give the highest values of storage roots yield, marketable yield, marketable roots, average weight, diameter and percentage of dry matter of storage roots in both seasons. Adding treatment 2, T3, T4, T5, and T6 increased roots yield by 15.2, 19.3, 9.1, 12.1, and 12.7%, respectively in the first season as well as 16.4, 19.2, 5.5, 12.9 and 13.9%, repectevely in the second season while the control (the plants weren't received treatments by B.bassiana) recorded the lowest results of all yield and its components of sweet potato in this study, they attributed these results to the effects of B. bassiana in nutrient uptake. Fungal endophytes might affect the nutrient cycle and uptake of nutrients from the soil by plants (Saikkonem et al., 2015).

Organic and Chemical Composition:
Date in Table (

Population Dynamic of Whitefly of Sweet Potato Treated With Endophytic B. bassiana and Control in Sohag governorate:
The graphically plotted data in Fig. (1)shows the weekly whitefly census on 25 leaves of sweet potato plants untreated with B. bassiana fungus, as well as weekly data for different treatments with B. bassiana fungus. The drawing indicates the escalation of the whitefly population on the leaves of non-treated sweet potato plants until reached their peak on the 10 th Aug. with an average population of 197 individuals/25 plant. The timing of adding the fungus treatments to the plants is indicated in Fig. (1), and the results of using endophytic B. bassiana is clear in the graph, where the fungus kept the infection rate of whitefly low throughout the season compared to untreated plants in 2018 season.

Damage of Whitefly of Sweet Potato Treated with Endophytic B. bassiana and Control in Sohag Governorate:
Data in Table (5) show the effect of fungus treatment, soil addition (once and twice), foliar application (once and twice), Foliar+Soil application on whitefly, leaf defoliators, root defoliators and control (untreated) in two successive seasons. Data indicated the significant effect of fungus on studied pest infestations.
Twice foliar application treatment was recorded the lowest number of whitefly by 32.94 individuals/ 25 leaves with significant differences with untreated and other treatments in 2018 and 2019 seasons with LSD= 4.82 and 4.9 respectively. One foliar and foliar+soil treatment were come in the second significant group after twice foliar application, without significant differences with each other in two successive seasons.
The Kasopers (1965)formula was used to calculate the percentage of damage in the leaves and roots of the sweet potato. The damage in the leaves was calculated before the week of harvest and the root damage was calculated immediately after harvest. The results showed that the use of B. bassiana in all treatments had a positive effect on infection rates for leaves and tuber roots compared to untreated sweet potato plants. The minimum damage percentages in leaves and tuber roots were observed in two foliar treatments (0.28%) and in two soil addition treatments (0.21%) respectively for 2018 season. The same trend was counted in the second season, by 0.28% and 0.26% damage of leaves and tuber roots. These results can attempt from many authors which they studied the effect of endophytic fungi on plant and evidence insects. Fungal endophytes improve the colonized plant height, weight and other growth parameters are also influenced. Jaber and Enkerli (2017) reported an improvement in the height, fresh weight of shoots and roots of V. faba plants following artificial inoculation of B. brongniartii, B. bassiana and M. brunneum. In another study, B. bassiana and P. lilacinum also increased the growth and dry biomass of colonized cotton plants (Lopez and Sword, 2015).
Fungal endophytes can also act as insect pathogenic agents by infesting lepidopterous larvae, aphids, thrips, and other cosmopolitan insects, which are of great concern in agriculture worldwide. They are known to infect specific hosts and pose little or no risk to non-target organisms or beneficial insects (Akutseet al., 2014). Existing of fungal endophytes symbiotically within the host plants acts as an indirect defense against herbivores (Powell et al., 2009 andQuesada-Moraga et al., 2009). Akutse et al., (2013) observed that endophytic fungi reduce insect herbivore damage are numerous, some of the common measures include: reduction in the insect developmental rate.