Effects of Vitamins B1, B2, PP, and Physiologically Active Substances on Rice under Varying Levels of NPK and Oxygen Nutrition

Introduction

The practice of growing high rice yields has shown the negative impact of excessive nitrogen fertilizers on this crop. Analyses have revealed that in flooded rice plants containing excessive nitrogen, no significant increase in protein nitrogen content was observed, but the content of soluble nitrogen (amino and amide) sharply increased.

Small amounts of certain physiologically active substances enhance the plant's ability to tolerate high nitrogen doses by stimulating respiration, which increases the plant's energy potential and accumulates Krebs cycle acids that bind ammonia. According to L.A. Khristeva's theory, the amount of assimilable nitrogen is limited by the number of matrices for protein molecule synthesis. Physiologically active substances affect the RNA-DNA system, increasing the synthesis of mobile RNA forms, especially messenger RNA, which improves nitrogen assimilation.

The main building blocks for nucleic acid biosynthesis are activated nucleoside-5-triphosphates, formed by the interaction of nucleoside mono- or diphosphate with the activated pyrophosphate group of ATP.

Growing rice under a layer of water creates an oxygen deficit, limiting ATP synthesis and, consequently, labile RNA forms. Introducing physiologically active substances alleviates oxygen deficiency, enhancing nucleic acid synthesis and plant resistance to high nitrogen doses.

Experimental Part

Vegetation experiments were conducted in sand culture using Pryanishnikov's mixture with 1, 2, and 4 doses of nitrogen. The following were used:

• Potassium humate (0.005%).
• Vitamins B1, B2, and PP (5 mg/kg of sand).

Experiments lasted 24 days with three replicates. Oxygen nutrition conditions varied:

1. Soil moisture at 60% of full water capacity.
2. Alternating: 1/3 of the time at 60% moisture, 2/3 under flooding (0.5 cm).

Results

Graphs show that the greatest effect of physiologically active substances is achieved under oxygen deficiency and high nitrogen doses. Without flooding, their influence is less significant.

Field Experiments (2020-2021)

Humic fertilizer Adept Agro.Bio was applied (composition in Table 1).

Table 1. Chemical Composition of NPK + Humate

Fertilizer Type	pH (aqueous)	Humic Acid, %	Nitrogen (hydrolyzable), %	P2O5 (hydrolyzable), %	K2O, %
NPK+humate (2020)	7.2	0.2	0.4	0.64	0.47
NPK+humate (2021)	7.1	0.16	0.82	0.80	0.70

Table 2. Efficiency of NPK + Humate for Rice

Experiment Scheme	2020		2021
	Yield, c/ha	Increase, %	Yield, c/ha	Increase, %
Control (N120P100)	63.3	---	44.6	---
Background + NPK +humate, 10 t/ha	68.6	8.3	49.3	10.3
Background + N20P31K23 (equivalent to 10 t/ha)	64.7	0.7	46.0	3.1
Background + NPK +humate, 15 t/ha	76.5	20.9	49.9	11.6
Background + N30P48K34 (equivalent to 15 t/ha)	---	---	47.3	5.9
Background + NPK +humate, 20 t/ha	77.2	21.9	51.0	14.1
Background + N40P64K46 (equivalent to 20 t/ha)	---	---	45.6	2.2

NPK +humate showed significant advantages over mineral equivalents, especially under high agricultural conditions. Humic fertilizers also accelerated maturation and reduced empty grains.

Study of First-Generation Seeds (2021)

Table 3. Effect of Humic Fertilizers on Rice Seeds

Experiment Scheme (2020)	Germination, %	Germination Energy (Day 4)	Biometric Indicators (Day 14)
Control (N120P100)	98	73	Stem length: 7.9 cm; Roots: 39 cm
Background + NPK +humate, 5 t/ha	99	95	Stem length: 12.7 cm; Roots: 64 cm
Background + NPK +humate, 10 t/ha	99	91	Stem length: 11.0 cm; Roots: 61 cm
Background + NPK +humate, 15 t/ha	100	92	Stem length: 11.9 cm; Roots: 54 cm
Background + NPK +humate, 20 t/ha	99	87	Stem length: 12.1 cm; Roots: 54 cm
Background + N20P32K23 (equivalent)	99	73	Stem length: 10.1 cm; Roots: 51 cm

Table 4. Biochemical Indicators of 14-Day-Old Rice Plants

Experiment Scheme	Catalase Activity, ml/g	Chlorophyll, mg	Vitamin C, mg%	Monosaccharides, mg	Disaccharides, mg	Total Nitrogen, %
Control	216	122.6	26.4	1.08	0.1	3.28
N120P100 (Background)	243	143.3	33.4	0.8	1.0	3.22
Background + NPK +humate, 5 t/ha	192	197.3	33.4	1.08	0.72	3.40
Background + NPK +humate, 10 t/ha	288	203.5	33.4	0.8	1.0	3.50
Background + NPK +humate, 15 t/ha	264	126.5	33.4	0.71	1.0	2.87
Background + N20P32K23	214	123.9	26.4	1.17	0.63	3.16

Conclusions

1. Physiologically active substances are most effective under oxygen deficiency and nitrogen excess.
2. Humic fertilizers (NPK +humate) increase rice yield by 8-22% compared to mineral equivalents.
3. Treatment with humic fertilizers improves germination, germination energy, and biochemical indicators of first-generation seeds.
4. Further study of the effects of humic substances on plant hereditary properties is promising.

Conclusion

The application of humic fertilizers with physiologically active components optimizes nitrogen metabolism, reduces the toxicity of high nitrogen doses, and adapts rice to oxygen-deficient conditions.