Potato cultivation (Solanum tuberosum L.) has great relevance for agriculture, however, great variability has still been observed in productivity rates and production quality. Brazilian producers seek to raise the average to 40t/ha considering the productive potential of the Ágata cultivar, however, the national average is still approximately 20t/ha and for the South Region the values are even lower. To increase productivity levels, it is necessary to generate information to better support management, particularly cultural management practices. In this particular case, hilling and spacing between plants have a great influence on the formation and production of tubers.
Hilling can have effects on productivity as it tends to create a better environment for the development of tubers due to the greater volume of soil in the adjacent surface layer. However, the most easily perceived effects are in relation to the characteristics of the harvested tubers, as without hilling those located more superficially in the soil tend to be exposed to sunlight, especially in the final stages of the cycle.
In tubers exposed to light, a greening process is triggered, which occurs due to the synthesis of chlorophyll with the transformation of amyloplasts into chloroplasts, associated with the accumulation of glycoalkaloids that alter the flavor of the tubers, reducing the possibility of commercialization. This process varies between genotypes, with Agate being considered prone to strong greening.
To define the best spacing between tubers when planting, one must take into account whether the purpose of production is for consumer potatoes or seed potatoes, as this factor affects the size of the tubers produced, this being a characteristic that has represented concern among farmers. producers.
The results presented in this article come from research developed with the aim of evaluating the effects of different spacing of plants in the crop row and hilling times on the productivity and characteristics of potato tubers, with the aim of defining the best combination of these factors for crop management in the field.
The experiment was developed with the Department of Agronomy, on the Campus of the State University of the Center-West (Unicentro), in Guarapuava, Paraná, 25°23'02” S, 51° 29'43” W. The regional climate is classified as Cfb – humid mesothermal subtropical. The soil at the site is classified as a dystroferric bruno latosol. Approximately 60 days before planting, liming was carried out with the aim of raising the soil pH to 6,2.
Potato planting was carried out on December 23rd using the Ágata cultivar with certified first generation seed tubers (G1), type 2 (diameter between 40mm and 50mm). A completely randomized 4 x 4 factorial design with four replications was used, consisting of four hilling management/times: 1) hilling at planting (considered early), 2) hilling on January 19, ten days after planting. emergence (DAE), this being the most widespread practice among producers in the region, 3) hilling on January 29th at 20 DAE, and 4) Without hilling and four plant spacings in the row, being: 16cm, 22cm, 28cm and 34cm, which resulted in a population of 78.125, 56.818, 44.643 and 36.765 plants/ha, respectively. Each plot consisted of four rows 6m long, with four meters being evaluated from the two central rows. Plant desiccation was carried out at 85 DAE with the aim of standardizing the characteristics of the tubers for the harvest that took place on April 20 at 100 DAE.
The characteristics analyzed were productivity, average tuber mass; average number of tubers per plant and the rate of occurrence of tuber greening. The occurrence and intensity of greening were considered, the latter analysis being carried out by assigning percentage values according to the green area of each tuber: 1% to 30% (weak greening), 50% (medium greening), 70 % (strong greening) and 90% (very strong greening).
Results and discussion
The evaluations demonstrated that the increase in the spacing of plants in the row is accompanied by a sequential increase in the size of the tubers produced, and in this condition the number of tubers per plant showed the opposite behavior, decreasing with the increase in spacing. Productivity, being a result of the association of these two factors, presented behavior that can be clearly represented by a quadratic equation, as can be seen in Figure 1 (A), (B) and (C).
In this case, for the production of consumer potatoes, where larger tubers are preferred, the best alternative would be to use lower plant densities. This result contributes to consolidating the trends of a large part of Brazilian crops, in which producers have realized over time that in areas for the production of tubers for consumption, the productivity resulting from high plant densities is generally not worth it, due to the need greater quantity of seed potatoes and a reduction in market value due to the smaller size of the tubers produced. On the contrary, increasing plant density can be an appropriate management strategy when the objective is the production of seed tubers, where, unlike consumption standards, smaller tubers are preferred.
The average number of tubers per plant was significantly affected by hilling times. Plants grown under the conditions of treatments without hilling and hilling at planting produced a greater number of tubers and consequently presented greater productivity (Table 1).
Tabela 4 - Average number of tubers per plant, subjected to four hilling periods
| Treatment | Number of tubers (plant-1) | Productivity (kg ha-1) |
| Hill up when planting | 12,114 to | 61.990 to |
| Add up to 10 DAE | 11,053 b | 49.495 b |
| Add up to 20 DAE | 10,647 b | 47.234 b |
| No pile | 11,703 to | 60.908 to |
| DMS | 0,561 | 10,52 |
Treatment
Number of tubers
(plant-1)
Productivity (kg ha-1)
Hill up when planting
12,114 to
61.990 to
Add up to 10 DAE
11,053 b
49.495 b
Add up to 20 DAE
10,647 b
47.234 b
No pile
11,703 to
60.908 to
DMS
0,561
10,52
Means followed by the same letter do not differ statistically from each other using the Tukey test (p < 0,05).
Under cultivation conditions without hilling, the tubers showed a higher rate of occurrence and intensity of greening (Table 1). This is a result that is fundamentally due to the more immediate effect caused by the practice of hilling, by the increase in the layer of soil over the tubers, tending to prolong the period in which they remain sheltered from the incidence of direct light, in contrast to the effects caused by growth of those more superficial and, especially of precipitation, which act by reducing the thickness of the soil layer over the tubers. In this cultivation without hilling, the reduction in plant spacing increases the incidence of greening of the tubers, as it causes greater exposure to light with the emergence of the tubers towards the soil surface.
Tabela 2 - Occurrence rate and intensity of greening of potato tubers subjected to four hilling managements
| Heaps | Greening (%) | |
| Occurrence | Intensity | |
| Hill up when planting | 4,68 b | 0,44 b |
| Add up to 10 DAE | 5,23 b | 0,34 b |
| Add up to 20 DAE | 8,33 b | 0,91 b |
| No pile | 21,87 to | 1,66 a |
| DMS | 6,02 | 0,82 |
Heaps
Greening (%)
Occurrence
Intensity
Hill up when planting
4,68 b
0,44 b
Add up to 10 DAE
5,23 b
0,34 b
Add up to 20 DAE
8,33 b
0,91 b
No pile
21,87 to
1,66 a
DMS
6,02
0,82
Means followed by the same letter do not differ statistically from each other using the Tukey test (p < 0,05).
The early hilling carried out at planting proved to be an alternative that should be considered carefully by producers, as it demonstrated efficiency in reducing greening, at the same time as it has the advantage of not causing damage to the plants due to the action of the cultivating equipment used. Such damage was evident in the late hilling at 20 DAE, which served as a gateway for pathogens with a visible increase in the incidence of diseases, especially late blight (Phytophthora infestans) and black cinnamon (Alternaria Solani) even with preventive treatments applied.
Conclusions
Increasing the spacing of plants in the row provides better conditions for the production of potatoes for consumption, increasing the size and average mass of the tubers produced. For the production of seed potatoes, smaller spacings should be preferred.
Hilling reduces the incidence of greening of the tubers produced. This practice, when prior to plant emergence, also benefits crop productivity.
Cultivation with approximately 34cm spacing between plants in the row, associated with hilling at the time of planting, stands out as the best management alternative for potato production for consumption.
Click here to read the full article from Cultivar Hortaliças e Frutas, edition 80.
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By José Otavio Menten, President of the Sustainable Agro Scientific Council (CCAS), Agronomist, Master and Doctor in Agronomy, Post-Doctorate in Pest Management and Biotechnology and Senior Professor at ESALQ/USP; and you
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