Biofertilization with beneficial microorganisms and low rates of chemical fertilization in potatoes (Solanum tuberosum L.) management for sustainable agriculture

Biofertilização com microrganismos benéficos e baixas taxas de fertilização química na batatata (Solanum tuberosum L.) para uma agricultura sustentável

Abstract

Potato is considered one of the most important crops in the world. However, biotic and abiotic factors can considerably affect the production of this crop and increase production costs, the biofertilizers are environmentally friendly alternatives that could reduce these problems. The objective was to determine the biofertilizer activity of Trichoderma harzianum and Bacillus subtilis as a sustainable alternative to reduce chemical fertilization in potato productivity. In this research, two potato varieties (commercial variety Yungay and the improved variety 302295.32), two beneficial microorganisms (Trichoderma harzianum and Bacillus subtilis both at a dose of 1 kg ha^-1) and three doses of chemical fertilization (20, 50 and 100% NPK) and a control (commercial variety Yungay at a dose of 100% NPK) were used in a 2x2x3+1 factorial scheme. The findings obtained reported that the use of the variety CIP302295.32 biofertilized with T. harzianum can obtain similar results using less chemical fertilizers compared to high NPK doses. The highest biometric parameters in potato were achieved in the treatments, variety CIP 302290.11 inoculated with T. harzianum at doses of 50 and 100% of NPK, so that at a dose 50% less fertilizer produced an increase of 24. 39% in the number of tubers per plant compared to the control and in the number of commercial tubers per plant the increase was 50.31%. This same treatment had a significant effect on yield parameters, increasing by 42.17% in total yield and 49.09% in commercial yield compared to the control. Therefore, this research demonstrated that biofertilization of the improved variety 302295.32 with T. harzianum at a dose of 50% NPK is a valuable alternative to increase the yield of sustainable potato cultivation in Peruvian Andean.

Keywords:
biofertilizers; chemical fertilization; Trichoderma harzianum; variety

Resumo

A batata é considerada uma das culturas mais importantes do mundo. No entanto, os fatores bióticos e abióticos podem afetar consideravelmente a produção dessa cultura e aumentar os custos de produção. Os biofertilizantes são alternativas ambientalmente amigáveis que podem reduzir esses problemas. O objetivo foi determinar a atividade biofertilizante de Trichoderma harzianum e Bacillus subtilis como alternativa sustentável para reduzir a fertilização química na produtividade da batata. Nesta investigação, foram utilizadas duas variedades de batata (a variedade comercial Yungay e a variedade melhorada 302295.32), dois microrganismos benéficos (Trichoderma harzianum e Bacillus subtilis, ambos na dose de 1 kg ha^-1) e três doses de fertilização química (20%, 50% e 100% NPK), além de um controle (variedade comercial Yungay na dose de 100% NPK), em um esquema fatorial 2x2x3+1. Os resultados obtidos indicaram que o uso da variedade CIP 302290.11 biofertilizada com T. harzianum pode alcançar resultados semelhantes usando menos fertilizantes químicos em comparação com altas doses de NPK. Os parâmetros biométricos mais elevados na batata foram alcançados nos tratamentos com a variedade CIP 302295.32 inoculada com T. harzianum em doses de 50% e 100% de NPK, de modo que, com uma redução de 50% na dose de fertilizante, houve um aumento de 24,39% no número de tubérculos por planta em relação ao controle, e no número de tubérculos comerciais por planta, o aumento foi de 50,31%. Este mesmo tratamento teve um efeito significativo nos parâmetros de rendimento, com aumento de 42,17% no rendimento total e 49,09%na produtividade comercial em comparação ao controle. Portanto, esta pesquisa demonstrou que a biofertilização da variedade melhorada CIP 302295.32 com T. harzianum na dose de 50% NPK é uma alternativa valiosa para aumentar o rendimento do cultivo sustentável de batata no norte dos Andes do Peru.

Palavras-chave:
biofertilizantes; fertilização química; Trichoderma harzianum; variedade

1. Introduction

Potato (Solanum tuberosum L.) highly produced and consumed crop worldwide due to great nutritional contribution and economic income for farm families (Alfiky et al., 2024). However, the most consumed potato at national and international level is white-fleshed tuber, which has attributes for industrialization and yield (Vásquez et al., 2022). In Peru, potatoes with pigmented pulp have natural pigments with high antioxidant capacity and bioactive compounds beneficial to human health and nutrition, their production growing rapidly (Tirado-Malaver et al., 2024).

Likewise, crops respond differently to fertilization, being potato a highly demanding crop in nutrients and water, because it produces a high foliar mass which is responsible for supplying photosynthates to its tubers (Abdirahman et al., 2022). However, the attack of phytopathogens causes severe stress on the plant and to counteract this effect the farmer continuously applies pesticides to control the attack and its infection by the pathogen, while the plant expends molecular energy for its recovery, limiting the yield (Xiao et al., 2023). Because of these problems, the farmer increases the doses of chemical fertilizers to counteract the weakening of the plants and achieve high yields (Ibáñez et al., 2023).

Addition, potato plant requires a nutritional balance for proper physiological functioning. According to Pirttilä et al. (2021) main commercial fertilizers are nitrogen (N), phosphorus (P) and potassium (K) which play an important role in crop productivity, but cause a negative impact because the plants have an insufficient uptake of fertilizers because when applied to soil series events such as leaching, precipitation, among others causing eutrophication which causes an imbalance soil fertility, increase production costs and impact greenhouse gas emissions.

Another serious problem is the stress caused by a low response in the uptake of nutrients from the soil, because the photosynthates that are destined to the root system is less since these photosynthates are used for the recovery of tissues damaged by biotic and abiotic factors in the plant through the production of secondary metabolites and enzymes that are responsible for reducing oxygen free radicals and the regeneration of plant tissue from cell division by which the plant exceeds molecular energy (Bandara and Kang, 2024; Chaudhary et al., 2022). Meanwhile, the plant does not take full advantage of the nutrients in the soil, and the only solution is to increase the dose of chemical fertilization, which alters the soil biota and contaminates the aquifers, and fertilizers currently have a higher price compared to a few decades ago, and prices are likely to increase as the fossil resource is used up, causing great uncertainty in the future of agricultura (Ibáñez et al., 2023).

All these problems lead triple negative effect, due to indiscriminate use of pesticides and high doses of chemical fertilizers that increase costs of production, pollute the environment (soil, water and air) and cause a detrimental risk to farmer's health (Kredics et al., 2024).

In view of this fact, different alternatives are being sought, and according to Vásquez et al. (2022), the most economical of these is the use of genetic improvement, which can be used to produce varieties resistant to stress factors. This situation suggests the need to evaluate improved potato varieties with pigmented flesh (Tirado-Lara et al., 2020) since these varieties present natural pigments such as anthocyanins, rivoflabins, tocopherols and other bioactive compounds with high antioxidant capacity that are responsible for inhibiting oxygen free radicals generated in response to stress, so that plant would reduce the expenditure of molecular energy, maintaining its agronomic and nutritional attributes.

Furthermore, the use of microbial inoculants is a reliable alternative to the excessive use of chemical fertilizers (Abioye et al., 2024). Several authors confirm that the use of beneficial microorganisms in agricultural production is beneficial due to their ability to colonize the soil rhizosphere and through it produce organic substances with dual action (biofertilizer and biofungicide) which reduces the attack of soil phytopathogens and increases the availability and uptake of nutrients (Benigno et al., 2024). It should be noted that beneficial microorganisms do not provide nutrients as such, their function is to solubilize nutrients that are precipitated in the soil, such as phosphate, potassium, ammonium or other minerals, making them available for uptake (Kowalska et al., 2022). It also stimulates the synthesis of endogenous hormones in the plant (Lopes et al., 2021). This results in greater availability and utilization of nutrients from the chemical fertilizer applied, improves the plant's defensive system, reduces stress from biotic and abiotic factors and maintains soil fertility (Seenivasagan and Babalola, 2021).

Indeed, there is a great diversity of beneficial microorganisms, however, T. harzianum and B. subtilis are two microorganisms that through several studies have demonstrated their high beneficial capacity in favor potato yield without causing damage to the environment by reducing the use chemical pesticides and with use of improved varieties of pigmented pulp are promising strategies that ensure less use chemical fertilizers (Zainuddin et al., 2022; Angulo et al., 2020). In this situation, the objective was to determine the biofertilizer activity of Trichoderma harzianum and Bacillus subtilis as a sustainable alternative to reduce chemical fertilization in potato productivity.

2. Materials and Methods

The experiment was conducted in the experimental field of ACOMEBIO (Association for the conservation of the environment and biodiversity), located in the rural area of El Pargo in the province of Cutervo, Cajamarca, located at 6°22’53” South Latitude and 78°49’06” West Longitude, and at an altitude of 2617 meters above sea level.

2.1. Methodology

The experimental design was completely randomized blocks using a factorial scheme of 2 x 2 x 3 + 1 additional (control). This consisted of two potato varieties (clone CIP 302295.32 and Yungay), two beneficial microorganisms (Trichoderma harzianum and Bacillus subtilis), three fertilization doses (minimum, medium and high) and an additional treatment consisting most used variety in region and high dose used by majority producers in potato-growing area of northern highlands Peru. Four replications were used

Soil analysis the experimental field was carried out before planting, showing that soil is sandy loam, pH of 6.32 being slightly acidic, with 2% organic matter, electrical conductivity of 0.91 dS/m (without salinity problem), in terms nutrient content these were: P (85 mg kg^-1), K (158 mg kg^-1), Ca²⁺ (15. 2 meq/100g), Mg²⁺ (10.21 meq/100g), Na⁺ (0.09 meq/100g), cation exchange capacity (11.32) and no deficiency microelements.

2.2. Treatment description

The treatments used in this research consisted of T. harzianum strain 1123 at a dose of 1 kg ha^-1, B. subtilis strain 2233 at a dose of 1 kg ha^-1 both applied 10 days before sowing to ensure proliferation of the microorganisms, applied with three doses of fertilization at 20% N-P-K (minimum) equivalent to 62. 5-37.5-50 kg ha^-1 N-P-K, 50% N-P-K (medium) equivalent to 125-75-100 kg ha^-1 N-P-K and 100% (high) equivalent to 250-150-200 kg ha^-1 N-P-K, respectively. Two varieties were planted: Yungay variety, the most widely used in region due to its attributes for industrialization and yield and improved variety with pigmented pulp CIP 302295.32. Therefore, they were established as: T0 (Yungay variety without microbial inoculation, with 100% doses NPK) as the control, T1 (Yungay variety with T. harzianum to a 20% dose NPK), T2 (Yungay variety with T. harzianum to a 50% dose NPK T3 (Yungay variety with T. harzianum to a 100% dose NPK), T4 (CIP 302295.32 variety with T. harzianum to a 20% dose NPK), T5 (CIP 302295.32 variety with T. harzianum to a 50% dose NPK), T6 (CIP 302295.32 variety with T. harzianum to a 100% dose NPK), T7 (Yungay variety with B. subtilis to a 20% dose NPK), T8 (Yungay variety with B. subtilis to a 50% dose NPK), T9 (Yungay variety with B. subtilis to a 100% dose NPK), T10 (CIP 302295.32 variety with B. subtilis to a 20% dose NPK), T11 (CIP 302295.32 variety with B. subtilis to a 50% dose NPK), T12 (CIP 302295.32 variety with B. subtilis to a 100% dose NPK).

2.3. Conducting experiment

Planting was carried out in the 2021-2022 growing season. The experimental unit consisted of three rows of 10 plants each, the distance between rows was 1m and between plants at 0.3m, and the sample consisted of 10 plants from the central row. Fertilization was carried out in two stages, as is done in potato production in the highlands of Peru, the first at the beginning applying 50% N and 100% P and K, then the second application was at 30 days, taking advantage of the change of furrow or hilling. Irrigation was by gravity. Pathogenic pests were controlled by integrated pest management. Harvesting was carried out 145 days after planting.

2.4. Agronomics parameters of potatoes

The following parameters were evaluated: plant height (PH), number of stems per plant (NSP), number of tubers per plant (NTP), number of non-commercial (NTNC) and commercial tubers per plant (NTC), weight of tubers per plant (WTP), weight of commercial tubers per plant (WCTP) (over 4cm), commercial yield (CY) and total yield (TY) were determined according to Tirado-Malaver et al. (2021).

2.5. Statistical analysis

The data obtained were processed through analysis of variance and significant differences were performed with Tukey's test at 5% error, then regression tests which were performed with the statistical package SAS (Statistical Analysis System).

3. Results and Discussion

3.1. Agronomic parameters

As shown in Table 1 the results of the mean squares of the analysis of variance are shown. The variables PH, NTP and NTNC presented significant effect (p<0.01) in the main factors, while the effect on the variable NSP was not significant. On the other hand, for the NTNC variable, the variety factor was not significant (p>0.05). Regarding the interaction of factors, the variables NTP and NTC showed significant effects in the interaction between beneficial microorganisms and fertilization levels, indicating that beneficial microorganisms responded to increasing doses of fertilization by increasing the number of tubers per plant. Likewise, the octagonal comparison (VxMxD vs. control) the variable NTP and NTNC showed interaction, showing variation of the interaction varieties, microorganisms and fertilization dose vs. control.

Table 1
Summary of analysis of variance for plant height (PH), number of stems per plant (NSP), number of tubers per plant (NTP), number of non-commercial (NTNC) and commercial tubers per plant (NTC) of potatoes.

Source of Variation	MS
	DF	PH	NSP	NTP	NTC	NTNC
Blocks	3	26.21ns	0.11ns	0.69ns	1.18ns	0.08ns
Variety (V)	1	219.31**	0.08ns	20.02**	28.52**	1.02ns
Microorganism (M)	1	100.34**	0.08ns	22.69**	42.52**	2.52**
V × M	1	3.31ns	0.33ns	0.19ns	0.19ns	0.02ns
NPK dosage (D)	1	66.66**	0.44ns	20.31**	33.52**	1.31*
V × D	2	3.16ns	0.33ns	2.15ns	0.77ns	0.27ns
M × D	2	20.71ns	0.02ns	4.94**	3.06*	0.40ns
V × M × D	2	4.40ns	0.27ns	0.44ns	1.56ns	0.27ns
V × M × D vs. control	1	6.04ns	0.00ns	0.13ns	5.58*	4.17**
Error	33	11.57	0.2	0.61	0.74	0.3
Total	47
VC (%) =		5	13.83	9.85	16.48	19.9

• Note: VC (%) = Variation Coefficient; DF = Degrees of freedom; MS = Mean Squares; ns= not significant (p>0.05),
• ^*
  = significant (p<0.05);
• ^**
  = highly significant (p<0.01).

Since there was no interaction between three factors, the analysis of main effects was carried out, which is shown in Figure 1. When analyzing the varieties separately, it was observed that the variety CIP 302290.11 was statistically superior to the variety Yungay, producing an increase in PH (70.12cm), NTP (8.58 tubers), NTC (6 tubers), respectively (see Figures 1A and 1B). Regarding the levels of beneficial microorganisms, T. harzianum presented the highest significant effect on PH (69.43 cm), NTP (8.63 tubers), NTC (6.17 tubers) respectively (see Figure 1C). Regarding fertilization levels, 50 y 100% doses NPK were significant with 69.33 and 68.98 cm height, 8.88 and 8.25 TP, 6.55 and 5.63 CTP respectively (see Figure 1D).

Figure 1
Simple effect for plant height (A), varieties (B), beneficial microorganisms (C), fertilization levels (D) of potatoes. NSP = number of stems per plant; NTP = number of tubers per plant; NTC = number commercial tubers per plant; NTNC = number of non-commercial. Note: Means with a common letter are not significantly different according to Tukey's test (p < 0.05).

The agronomic parameters are summarized (as shown in Table 2). It is shown that treatments T9, T8, T3 and T2 were statistically superior to the control for the variables NTP and NTC, while for PH, NSP and NTNC they were homogeneous. It can be observed that the improved variety CIP 302295.32 biofertilized with T. harzianum was favored by increasing the fertilization doses, producing a higher NTP, in addition to an increase in PH. Thus, the variety CIP 302295.32 applied with T. harzianum and 50% NPK produced an increase of 24.39% compared to the control, and the number of commercial tubers increased by 50.31%, which means that the improved variety shows a good plant development when using half of fertilizers and was favored by using T. harzianum. On the other hand, the Yungay variety biofertilized with T. harzianum at medium and high fertilization levels increases the PH y NTP.

Table 2
Multiple comparison of means according to Tukey's test for plant height (PH), number of stems per plant (NSP), number of tubers per plant (NTP), number of non-commercial (NTNC) and number commercial tubers per plant (NTC) of potatoes.

Treatments	PH	NSP	NTP	NTC	NTNC
	…..cm.....	…….………....µ ± σ……………….....
T9	74.33 ± 1.61 a*	3.3 ± 0.43 a*	10.25 ± 0.83 a*	8.05 ± 0.71 a*	2.25 ± 1.61 b*
T8	73.53 ± 1.08 a	3.0 ± 0.00 a	9.75 ± 0.83 ab	7.50 ± 1.12 ab	2.25 ± 1.08 b
T3	69.53 ± 3.61 ab	3.8 ± 0.43 a	9.25 ± 0.43 abc	6.75 ± 0.43 abc	2.25 ± 3.61 ab
T2	69.35 ± 4.20 ab	3.3 ± 0.43 a	9.00 ± 0.71 abc	6.50 ± 1.12 abc	2.50 ± 4.20 ab
T12	64.30 ± 6.42 b	3.5 ± 0.50 a	8.25 ± 0.83 bcd	6.05 ± 0.71 abcd	2.25 ± 6.42 b
T7	67.63 ± 2.36 ab	3.3 ± 0.43 a	8.00 ± 0.71 bcd	5.50 ± 0.87 bcde	2.50 ± 2.36 ab
T6	68.95 ± 2.82ab	3.3 ± 0.43 a	7.75 ± 0.43 cd	5.05 ± 0.71 cdef	2.75 ± 2.82ab
T11	67.63 ± 1.84 ab	3.3 ± 0.43 a	7.75 ± 0.43 cd	5.25 ± 0.43 cdef	2.50 ± 1.84 ab
Control	66.70 ± 1.36 ab	3.3 ± 0.43 a	7.75 ± 0.43 cd	4.00 ± 0.71defg	3.75 ± 1.36 a
T10	66.93 ± 1.61 ab	3.0 ± 0.00 a	7.50 ± 0.87 cde	3.75 ± 0.43 efg	3.50 ± 1.61 ab
T5	66.15 ± 2.79 ab	3.0 ± 0.00 a	6.50 ± 0.50 def	3.25 ± 0.42 fg	3.25 ± 2.79 ab
T1	64.28 ± 0.76 b	3.3 ± 0.43 a	5.75 ± 0.50 ef	2.75 ± 0.43 g	2.75 ± 0.76 ab
T4	63.70 ± 3.40 b	3.3 ± 0.43 a	5.50 ± 0.83 f	2.50 ± 1.12 g	3.25 ± 3.40 ab

• ^*
  Means ± standard deviation. Means with a common letter are not significantly different according to Tukey's test (p < 0.05).

3.2. Yield parameters

ANOVA analysis of the variables related to yield parameters (as shown in Table 3) showed that both the main factors and the interaction between beneficial microorganisms and fertilization had a significant effect on WPT, WNCTP, TY and CY respectively. This indicates that the microorganism’s factor responded to the increase in fertilization levels. While the effect of other interactions was not significant, the octagonal comparison (VxMxD vs. control) presented highly significant differences for all the variables under study.

Table 3
Summary of analysis of variance for weight of tubers per plant (WTP), weight of commercial tubers per plant (WCTP), weight of non-commercial tubers per plant (WNCTP), Total yield (TY) and commercial yield (CY) of potatoes.

Source of Variation	MS
	DF	WTP	WNCTP	WCTP	TY	CY
Blocks	3	16999.95ns	18736.11ns	66.80ns	18.88ns	20.81ns
Variety (V)	1	455929.58**	495157.81**	809.34ns	506.35**	549.66**
Microorganism (M)	1	663569.79**	737780.18**	1966.34**	737.59**	819.81**
V × M	1	3940.38ns	3486.38ns	13.89ns	4.37ns	3.84ns
NPK dosage (D)	1	538410.36**	586698.48**	1039.23*	598.25**	651.58**
V × D	2	15905.43ns	13100.16ns	210.15ns	17.61ns	14.55ns
M × D	2	56358.65*	52777.76*	312.68ns	62.41*	58.58*
V × M × D	2	23138.71ns	27496.18ns	205.34ns	25.81ns	30.76ns
V × M × D vs. control	1	90377.55**	127641.80**	3208.24**	100.34**	141.96**
Error	33	11560.73	12933.24	235.34	12.86	14.39
Total	47
VC (%) =		14.27	17.16	19.72	14.06	16.84

• Note: VC (%) = Variation Coefficient; DF = Degrees of freedom; MS = Mean Squares; ns= not significant (p>0.05),
• ^*
  = significant (p<0.05);
• ^**
  = highly significant (p<0.01).

See Figure 2 for the effect of the main factors. The varieties analyzed separately show that the pigmented pulp variety CIP 302295.32 achieved the highest value in yield parameters than the commercial variety Yungay (see Figures 2A and 2B). Regarding T. harzianum outperformed B. subtilis with higher WPT (883.25 g plant^-1), WNCTP (814.91 g plant^-1), TY (29.43 t ha^-1) and CY (26.38 t ha^-1), respectively (see Figures 2C and 2D). With respect to fertilization levels factor, doses 50 and 100% NPK were significant in following yield parameters (see Figures 2E and 2F).

Figure 2
Simple effect for varieties (A and B), beneficial microorganisms (C and D), fertilizer dosage (E and F) of potatoes. WTP = weight of tubers per plant; WNCTP = weight of non-commercial tubers per plant; WCTP = weight of commercial tubers per plant; TY = Total yield; CY = commercial yield. Note: Means with a common letter are not significantly different according to Tukey's test (p < 0.05).

The effect of varieties, beneficial microorganisms and fertilization levels on yield parameters is summarized in the following (as shown in Table 4). The results reported that the treatments T9 with a weight of 1119.60 g plant-1, CW of 1056.46 g plant^-1, TY of 37.3 t ha^-1 and CY of 35.2 t ha^-1 and T8 with a weight of 1053.5 g plant^-1, CW of 990.27 g plant^-1, TY of 35. 1 t ha^-1 and CY of 33 t ha^-1 were statistically superior to the other treatments in all yield variables, although similar to T3, T2 and T12, which were statistically superior to the control in relation to the variables WPT, WNCTP, TY and CY. Indicating that the improved variety biofertilizer with T. harzianum at medium and high doses of fertilization achieved the best results in yield components. On the other hand, Yungay variety biofertilizer with T. harzianum and B. subtilis with a high dose of fertilization showed a higher yield than the control.

Table 4
Multiple comparison of means according to Tukey’s test for weight of tubers per plant (WTP), weight of commercial tubers per plant (WCTP), weight of non-commercial tubers per plant (WNCTP), Total yield (TY) and commercial yield (CY) of potatoes.

Treatments	WPT	WNCTP	WCTP	TY	CY
	................. g plant-1 ….…....		…………..,,,….…...t ha-1 …………………..
T9	1119.60 ± 54.44 a*	1056.46 ± 93.34 a*	63.14 ± 12.12 b*	37.30 ± 3.14 a*	35.2 ± 3.11 a*
T8	1053.50 ± 135.20 ab	990.27 ± 147.58 ab	63.23 ± 12.12 b	35.10 ± 4.61 ab	33.0 ± 4.92ab
T3	961.48 ± 50.39 abc	891.08 ± 57.18 abc	70.40 ± 14.00 ab	32.04 ± 1.68 abc	29.7 ± 1.91 abc
T2	928.38 ± 138.40 abc	858.01 ± 147.58 abc	70.37 ± 14.00 ab	30.94 ± 4.51 abc	28.6 ± 4.92 abc
T12	855.23 ± 54.33 abcd	792.02 ± 93.34 abcd	63.20 ± 12.12 b	28.50 ± 3.14 abcd	26.4 ± 3.11 abcd
T7	796.23 ± 83.73 bcd	725.93 ± 114.32 bcde	70.29 ± 14.00 ab	26.54 ± 3.56 bcd	24.2 ± 3.81 bcde
T11	763.38 ± 138.40 cde	693.03 ± 57.16 cdef	70.35 ± 14.00 ab	25.44 ± 1.68 cde	23.1 ± 1.91 cdef
T6	737.33 ± 106.85 cde	660.07 ± 93.34 cdef	77.25 ± 12.12 ab	24.57 ± 2.79 cde	22.0 ± 2.79 cdef
Control	609.23 ± 94.12 def	504.23 ± 89.10 defg	105.00 ± 12.12 a	20.30 ± 2.65 def	16.8 ± 2.97defg
T10	590.90 ± 67.02 def	492.61 ± 57.16 efg	98.29 ± 14.00 ab	19.67 ± 2.23 def	16.4 ± 1.91 efg
T5	520.43 ± 50.39 ef	429.37 ± 57.16 fg	91.06 ± 12.12 ab	17.33 ± 1.81 ef	14.3 ± 1.91 fg
T1	440.35 ± 94.12 f	363.04 ± 57.16 g	77.31 ± 12.12 ab	14.67 ± 1.81 f	12.1 ± 1.91 g
T4	421.35 ± 79.50 f	329.96 ± 147.58 g	91.39 ± 12.12 ab	14.03 ± 4.61 f	11.0 ± 4.92 g

• ^*
  Means ± standard deviation. Means with a common letter are not significantly different according to Tukey's test (p < 0.05).

From the table it is clear that variety CIP302295.32.11 biofertilizer with T. harzianum reached its highest value at a dose 50 and 100% NPK, so that at a dose 50% NPK promoted an increase of 42.17% in TY and 49.09% in CY compared to control.

Figures 3A and 3B shows the variables that are most associated with performance. The relationship between PH and YT was adjusted to a polynomial function, indicating that PH positively influenced YT in two potato varieties, beneficial microorganisms and fertilizer levels indicating that both variables present a left and right ascending regression line indicating that as PH and the NTP increase, yield is higher, so the improved variety presents better agronomic behavior in plant biofertilizer with T. harzianum improves the availability of nutrients from the fertilizers which favors plant growth and increase of NTP producing a higher potato yield.

Figure 3
Regressions for (A), beneficial microorganisms (B) of potatoes.

4. Discussion

At present, biological agents have achieved importance in agricultural production, due to their attributes as biofertilizers and biofungicides that favor the development of plant, reducing massive and intensive use of pesticides and chemical fertilizers, as well the lower risk to human health and environment (Kredics et al., 2024). However, improved varieties with natural pigments have antioxidant capacity whose activity is to reduce the negative effect of abiotic and biotic factors, whose bioactives are beneficial to human health (Vásquez et al., 2022). Therefore, the effect of improved variety biofertilizer with beneficial microorganisms and fertilization levels on agronomic parameters and potato yield was studied.

The present research showed that the improved variety CIP302295.32 inoculated with T. harzianum and dose 50% fertilization presented a significant effect on the agronomic parameters obtaining better height, increase in the NSP and NTP NTCP statistically superior to control. These results are similar to those found by Kilonzi et al. (2024) who tested applications of beneficial microorganisms with different doses chemical fertilization and found that combination of T. harzianum at a dose 50 and 75% NPK obtained a PH of 55 to 65 cm and a range 8 to 13 NTP superior to control. Similarly, Al-Zaidy and Al-Hilfy (2023) reported that at 50% chemical fertilization combined with T. harzianum there was an increase in agronomic parameters, the cause being this microorganism stimulates the biosynthesis of endogenous hormones in plant such gibberellins and auxins that help to root, which consequently increases the uptake of minerals. In addition, T. harzianum metabolizes gluconic acid and other organic acids which generates acidic conditions in soil leading to solubilization of P, K, Ca, Mg, Mn and Fe (Bandara and Kang, 2024). So such function of Trichoderma as biofertilizer have been studied by many researchers in potato and other crops, wheat (Xue et al., 2017), maize (Estévez-Geffriaud et al., 2020), cucumber (Liu et al., 2022), tomato (Bandara and Kang, 2024).

Thus, the improvement in potato plant growth through biofertilization with the beneficial microorganisms in two varieties agrees with previous studies by Aseel et al. (2023) who showed that increase in height of inoculated and stressed plants was favored by T. harzianum. However, the results show that the number stems was not significant in any cases, the results were close to Othman et al. (2022) who found that plants treated with T. harzianum with the addition of 25 and 50% NPK did not influence the NSP, but for PH it was significant and increased the NTP by 25%. In contrast, Abdirahman et al. (2022) found that inoculated T. harzianum to tuber-seed allowed greater bud sprouting leading to an increase in stem production per plant.

This research has shown that the commercial variety Yungay when applied with T. harzianum was favored when NPK doses were increased, improving its agronomic performance. On the other hand, improved variety CIP 302295.32 biofertilized with T. harzianum at a dose 50% NPK produced an increase in NTP of 24.39% compared to control and NTCP increase was 50.31%, which means that improved variety presents a good plant development when using half fertilizers and was favored when using Trichoderma, which is corroborated by Benigno et al. (2024) who demonstrated application T. harzianum potato is due to fact that microorganism proliferates the rhizosphere plant and fulfills its mechanisms action which increase NTP, indicate that this effect is due to fact that plant does not have much energy expenditure to recover from biotic and abiotic stress, since the genetic constitution of the improved genotype has the capacity to synthesize secondary metabolites with antifungal activity and in combination with the microorganism which synthesizes antibiotic compounds, it causes an effective control phytopathogens which consequently increases the continuous mobilization of carbohydrates and water from the foliar mass to the tubers.

This information supported by Bazghaleh et al. (2020) who demonstrated that efficiency of microorganism in crop is due to the genetic compatibility between plant and microorganism, taking into account that plant releases exudates which are sources of energy but not all of them, since these exudates depend on conditions of plant if present biotic or abiotic stress. This information explains how Trichoderma was more effective than B. subtilis, because the potato plant when affected by P. infestans causes the release of metabolites through the roots which allows a greater attraction and proliferation T. harzianum being more effective its action.

On the other hand, the greatest decrease in plant growth parameters was obtained with the Yungay variety at low NPK doses. Tirado-Malaver et al. (2024) indicate that this is due to the fact that the variety has been losing its physiological and sanitary qualities over the years and has become sensitive to both biotic and abiotic stress factors.

With respect to yield parameters, the study showed that the biofertilization of the variety CIP 302295.32 with T. harzianum reached its highest value at a dose of 50 and 100% NPK, so that at a dose 50% NPK it promoted an increase of 42.17% in total yield and 49.09% in commercial yield compared to control. This result indicated that the improved variety produces metabolites that reduce biotic and abiotic stress and increase its efficacy when combined with T. harzianum, which resulted in an increase in tuber weight and thus an increase in total and MPY. A similar result was observed by Abdirahman et al. (2022) who when applying T. harzianum combined with different levels of chemical fertilization in potato, found that at medium doses of fertilization and the microorganisms the yield increased by 20% more than the control and by 25.15% in the CY. Similarly Flores and Leon (2024) reported that inoculating T. harzianum in potato increased yield by more than 40% compared to the control.

The treatments with the lowest value in the yield components were recorded with the combination of the Yungay variety and B. subtilis, a result that indicates that the increase in total and commercial yield of this variety occurs as the dose fertilization increases, which differs with the use T. harzianum, since at a medium dose of NPK it obtained a total and commercial yield statistically similar to the high dose of NPK. This result is similar to that found by Othman et al. (2022) who reported that 50% NPK combined with T. harzianum achieved a significant increase in yield components, outperforming the control with 100% chemical fertilization.

In fact, according to Ibañez et al. (2023), yield depends on the amount of fertilizer supplied, since potato plant requires high nutrient content for its development and recovery after infection by phytopathogens or other stress factors. In addition, researchers such as Congera et al. (2021) indicate that potato is a crop with high demand for N, P and K, so lack of any of them would affect the total and commercial yield potato. These findings revealed that potato biofertilization with T. harzianum at reduced NPK levels significantly increased yield, because this bioagent has the ability to solubilize minerals that are precipitated in soil, such as P, K and Zn (El-Zehery, 2019), Therefore, this bioagent, through the release of organic acids, improves the availability of these nutrients from chemical fertilizers (Chaudhary et al., 2022). Furthermore, this increase also depends on plant modulating hormone signaling regulating plant physiology which improves nutrient uptake from the root zone plant. However, the effect of treatments with B. subtilis was limited despite the fact that several studies have confirmed that bacterium has same mechanisms of action causing an increase in yield of tomatoes, peppers and other solanaceous (Wang et al., 2019). However, in this research it was not found significance of this bacterium in comparison with Trichoderma, confirming what was previously mentioned by Bazghaleh et al. (2020) that Trichoderma has better genetic compatibility with potato since the plant when attacked by P. infestans causes the release of exudates which allows a greater attraction and proliferation of T.harzianum improving its mechanisms of action both as biofertilizers and biofungicide.

These findings revealed that the Yungay variety is sensitive to phytopathogens, which leads to the continuous use of fungicides, increasing the resistance of pathogens to chemical ingredients, reducing their efficiency and consequently causing a negative impact on soil, water and ecosystem alteration (Kowalska et al., 2022). This demonstrated that the beneficial fungus T. harzianum has a better capacity as a biofertilization agent in Peruvian Andean conditions by fulfilling its antifungal activity. Our results are in agreement with Alfiky et al. (2024) who confirmed that T. harzianum applied to the soil before transplanting and after a few days in potato increased the total yield by 30% compared to the control because this fungus has greater effectiveness in controlling Phytophthora significantly superior to other biological agents including B. subtilis so that the plant does not spend molecular energy for the recovery of damaged tissue and consequently uses all its energy to increase plant size and yield.

In this study it was also found that the use of an improved variety increases potato yield, this effect is due to fact that genetic constitution of the improved genotype with natural pigments increases the plant's defensive system through the activation of enzymes that biosynthesize phytoalexins and other phenolic compounds that reduce the attack of phytopathogens and when combined with T. harzianum, control is greater. Therefore, the mechanisms this microorganism that include competition, antibiosis, hydrolytic enzymes and mycoparasitism, added to stimulation phytohormones, solubilization minerals, production siderophores, reduction soil pH through organic acids that leads dissolve phosphates, all these characteristics allow an effective control of phytopathogens, greater availability of nutrients and use of fertilizers, rapid recovery of damaged tissues (Aseel et al., 2023; Woo et al., 2023; Chaudhary et al., 2022). Consequently, the improved variety combined with T. harzianum and at a dose 50% NPK increases height of plant and increases number tubercle and generates higher total and commercial yield, reducing the number of applications chemical fungicides, as well reducing doses chemical fertilization, favoring sustainable potato cultivation in Peruvian Andean.

5. Conclusions

Biotic and abiotic factors affect yield in potato-growing areas in the northern highlands of Peru, which increases the indiscriminate use of pesticides and, to counteract the damage to the plant, chemical fertilization doses are increased. The efficiency of biofertilizers presented a valuable alternative in potato crop development. The findings obtained reported that the use of the improved variety CIP302295.32 biofertilized with T. harzianum can obtain similar results using less chemical fertilizers compared to high NPK doses. The highest biometric parameters in potatoes were achieved in the improved variety CIP 302290.11 inoculated with T. harzianum at doses of 50 and 100% NPK. The use of 50% less fertilizer produced an increase of 24.39% in the NTP variable compared to the control, and the increase in NTC was 50.31%. This same treatment had a significant effect on the yield parameters, increasing total yield by 42.17% and commercial yield by 49.09% compared to the control. Therefore, this research demonstrated that biofertilization of the improved variety CIP 302295.32 with T. harzianum at a dose of 50% of chemical fertilization is a valuable alternative to increase total and commercial yield, reducing the number of applications of chemical fungicides, reducing the dosage of chemical fertilization, favoring sustainable potato cultivation in Peruvian Andean.

Data Availability Statement

Data is available upon request.

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Edited by

• Editor:
  Ana Paula Peron

Publication Dates

• Publication in this collection
  20 June 2025
• Date of issue
  2025

History

• Received
  29 Nov 2024
• Accepted
  17 May 2025