Introduction
The limited amount of organic matter in most potato-growing soils in the country reduces their biological activity and limits the availability and absorption of some nutrients by plants (Khatar et al., 2017). One of the most effective management strategies in this field is to maintain and enhance soil organic matter, because improving the physical and chemical conditions of the soil can greatly help increase yield and achieve sustainable agriculture. Due to the limitations and high costs of livestock and poultry manure, which are used as a major part of organic fertilizers in the country, efforts should be made to benefit from new organic sources such as blood meal, which is used in smaller amounts per unit area and at the same time provides higher nitrogen content to the plant. Blood meal is also known as a growth stimulant due to its high amino acid content (Bhunia et al., 2021). So far, have been down very few experiments to investigate the effects of blood meal especially under irrigation deficit conditions. Therefore, it was necessary to investigate the effects of using blood meal as a source of nitrogen-rich organic fertilizer under stress conditions on growth traits as well as its effects on production of this important product (potato) in this project in the country.
Materials and Methods
This research was conducted as a factorial experiment based on randomized complete block design at the Hamedan Agricultural and Natural Resources Research and Education Center (Ekbatan Agricultural Research Station). In this study two potato cultivars, Bamba and Sante, were considered as the first factor. The irrigation water amount was examined at three levels (100, 75, and 50 percent of Cumulative Evapotranspiration from Class A Evaporation Pan) and fertilizer treatments at three levels (chemical fertilizer, poultry manure, and blood powder. The use of chemical fertilizer was based on soil tests. Chemical fertilizer treatment was carried out by using 120 kg of pure nitrogen with urea source (260 kg of urea fertilizer per hectare), 150 kg of triple superphosphate, 100 kg of potassium sulfate and two injections of complete micro fertilizer at the flowering stage and two weeks after that. One third of urea fertilizer was applied at the time of planting time and the two other parts were applied as a top-dress form. Complete micro fertilizer injection was also performed in two simultaneous times in the blood meal and chicken manure treatments. The drip irrigation system and the tape type were placed at a depth of five to six centimeters on the ridge and at the time of planting the tubers. The growth stage traits including time to achieve 50% germination, date of full emergence and date of full coverage, chlorophyll content, stem length, internode length, number of nodes, number and length of stolons, leaf area, fresh and dry weight of roots and stems were measured. Chlorophyll content was measured using the Gross method (Gross, 1999). At harvest time, the total yield was calculated and the tubers produced were separated into three sizes; seed, large, and small. Tuber dry matter percentage and water use efficiency were also measured. The resulting data were statistically analyzed using SAS 9.1 software, and means were compared using Duncan's multiple range test with a five percent probability level.
Results and Discussion
The results of analysis of variance in the measured traits showed that the two treatments of irrigation levels and the kind of fertilizer did not have a significant effect on the time required to achieve 50% germination and complete emergence. However, the effects of irrigation levels and fertilizer type and their interaction were significant on other growing traits including time to reach full coverage, plant height at flowering, number and length of stolons, chlorophyll content, leaf area index and fresh and dry weight of roots and stems. The tuber dry matter percentage was not statistically affected by cultivar, but irrigation treatment had a significant effect (p≤0.05) on tuber dry matter percentage. The type of fertilizer was significant (p≤0.01) on the number of tubers in all three sizes, as well as water use efficiency and on yield and percentage of tuber dry matter. The interaction effect of irrigation treatment × fertilizer type was significant on tuber production in all three sizes, as well as tuber dry matter, total yield, and water use efficiency. An increase in the ratio of nitrogen to phosphorus leads to a relative increase in stolon length. While the opposite ratio leads to a decrease in stolon length. Establishing a proportional and balanced amount of these two elements and providing sufficient amounts of them depending on the nutritional needs of the potato leads to an increase in the number of stolons (Jackson, 1999). Recent research has demonstrated that chicken manure and blood meal are capable of significantly reducing stolon length and increasing their number under stress conditions. It seems that both of these types of organic fertilizers (blood meal and chicken manure) provide the potato plant with a balanced access of nitrogen to phosphorus under stress conditions and, by relatively increasing the stolon length and helping to increase its number, delay the potato plant's tuberization stage and achieve maximum storage capacity. The results of this study showed that under severe stress conditions, the use of blood meal had also positive effect on number of tubers and total yield compared to the use of chemical fertilizer alone (control) in deficit irrigation treatments by releasing amino acids and also helping to absorb nutrients. As a result, in conditions of severe stress, the use of blood meal regulates the effects of water stress and partially compensates adverse effects of deficit irrigation.
Conclusion
the results of this experiment showed that the use of chicken manure and blood meal significantly increased vegetative growth and yield of potatoes compared to chemical fertilizers. In addition, the effectiveness of both types of organic fertilizers was greater compared to chemical fertilizers under deficit irrigation conditions. Therefore the use of these two organic fertilizers, especially blood meal, can compensate the reduction of yield under water stress conditions. |
