What to Do About Low Potato Yields? Cause Analysis and Countermeasures

Potato (scientific name: Solanum tuberosum), a perennial herbaceous plant of the Solanaceae family, whose tubers are edible, is the third most important food crop in the world, after wheat and maize. Potato is also known as di dan, ma ling shu, yang shan yu, etc., the tuber of a Solanaceae plant. Together with wheat, maize, rice and sorghum, it is counted among the world's five major crops.

Morphological characteristics of the potato: herbaceous, with underground stem tubers, oblate or 15-80 cm tall, hairless or sparsely pubescent. The stem is divided into two parts: the aboveground stem and the underground stem. Oblong, about 3-10 cm in diameter, with white, pale red or purple skin. The skin color of the tuber is white, yellow, pink, red, purple or black, and the flesh is white, pale yellow, yellow, black, bluish, purple or blackish purple. Plants grown from seed form a slender main root and branched lateral roots; plants propagated from tubers have no main root and form only a fibrous root system. The aboveground stem is diamond-shaped and hairy. The primary leaves are simple and entire. As the plant grows, odd unequally pinnate compound leaves gradually form. The leaflets are often of alternating sizes, 10-20 cm long; the petiole is about 2.5-5 cm long;

The leaflets, 6-8 pairs, ovate to oblong, the largest up to 6 cm long and 3.2 cm wide, the smallest less than 1 cm in both length and width, with a pointed tip, a slightly unequal base, entire margins, both surfaces sparsely white-pubescent, with 6-7 lateral veins on each side, slightly curved at the tip, and a petiolule about 1-8 mm long. The corymb is terminal, later lateral, with white or blue-purple flowers; the calyx is bell-shaped, about 1 cm in diameter, sparsely pubescent outside, 5-lobed, the lobes lanceolate with a long acuminate tip; the corolla is rotate, about 2.5-3 cm in diameter, the corolla tube hidden within the calyx, about 2 mm long, the limb about 1.5 cm long, with 5 triangular lobes about 5 mm long; the stamens are about 6 mm long, the anther 5 times the length of the filament; the ovary is ovate, hairless, the style about 8 mm long, the stigma capitate. The berry is globose, smooth, green or purplish brown, about 1.5 cm in diameter. The seed is kidney-shaped and yellow. The flowering period is summer.

Causes of Low Potato Yields and Countermeasures

With the adjustment of the agricultural industrial structure, the potato planting area has gradually expanded. However, for potatoes planted by some farmers, the aboveground part grows very well, while the underground part produces few and small tubers, resulting in low yield and poor returns. To obtain high yields and achieve better economic returns, scientific management must be carried out according to the growth patterns of the potato.

I. Causes of low yields:

1. Mistakes in variety selection. First, choosing a variety with too long a growth period, because the most suitable temperature for the tuber formation stage of the potato is 16°C-18°C; when the temperature rises above 25°C, the tubers stop growing while the aboveground stems and leaves grow vigorously. When the temperature rises above 29°C, the growth of the aboveground stems and leaves is hindered, or they even wither and die, so the tubers are small and the yield is low. Second, poor disease resistance of the variety and seed-borne disease. Most farmers use their own saved seed without isolation or virus prevention measures, so after sowing the viral disease is relatively severe, affecting the normal development of the potato.

2. Sowing date too late. Generally, spring sowing is done in early to mid-April, and from sowing to the tuber formation stage is about 60-70 days, which falls in late June to early July, when the temperature is relatively high, so tuber formation and enlargement suffer, resulting in low yield.

3. Unsuitable crop rotation. Some crops are planted year after year, causing soil pathogens to accumulate and disease to become severe. Soil nutrients become imbalanced, especially a lack of trace elements, making the potato grow weakly and yield poorly.

4. Extensive management. Mainly insufficient supply of water and fertilizer or excessive application of nitrogen fertilizer, causing excessive aboveground growth and consumption of nutrients. If cultivation and hilling are not done in time, the soil becomes compacted and tuber enlargement is hindered. Pests and diseases are severe.

II. Measures to increase yield

1. Choose good varieties. Varieties should be selected according to local climatic characteristics, with high yield, disease resistance and good quality, and the growth period of the variety should especially be considered. It is best to use virus-free seed potatoes for sowing.

2. Reasonable crop rotation. Potato should not be continuously cropped, nor rotated with Solanaceae crops (eggplant, pepper, tomato, tobacco, etc.), and also should not be rotated with root-tuber crops such as sweet potato, carrot and sugar beet. The rotation period should be at least four years; in vegetable areas it can be rotated with non-Solanaceae vegetables such as Welsh onion, garlic and celery, and can also be rotated with cereal crops, legumes, cotton and other crops to reduce the occurrence of disease.

3. Determine a suitable sowing date. Choosing a suitable sowing date is the key to successful and high-yielding potato cultivation. Potato is a crop that prefers cool conditions, and the temperature during the tuber formation stage must not exceed 25°C. Based on temperature estimates, the most suitable sowing period in the Huang-Huai River basin is late February to early March; sprout the seed potatoes before sowing, and harvest in early June. In May the temperature is about 18°C-23°C, which is very favorable for tuber enlargement and can help achieve high yields.

4. Strengthen field management

First, apply heavy base fertilizer to build soil fertility. Because the potato growth period is short, the base fertilizer should be applied fully in one go, generally 3000-4000 kg of decomposed organic fertilizer per mu; for the application method, 70% can be incorporated during land preparation, and the remaining 30% used as seed fertilizer, applied in holes or furrows;

Second, prevent late frost damage. Late frost often occurs during the emergence stage, causing frost damage and dead seedlings. Therefore, seedling-stage protection should be strengthened, using mulching or smoke methods to avoid late frost damage;

Third, cultivate and hill the soil. During the tuber formation and enlargement stages, cultivate frequently and hill the soil in several passes to promote root growth and stolon formation, increase the number of tubers set, and ensure robust plant growth;

Fourth, remove flower buds. When potato flower buds form and the inflorescence is emerging, the flower buds should be removed in time to reduce nutrient consumption and help nutrient accumulation;

Fifth, foliar topdressing. If fertilizer runs short in the later stage, spray the leaves with a 0.1% magnesium sulfate solution and a 0.2%-0.3% potassium dihydrogen phosphate solution, spraying 40-50 kg of fertilizer solution per mu.

5. Control pests and diseases. From sowing to harvest, the control of viral disease must be given top priority, with agricultural control measures as the main approach, and aphids should be controlled promptly to reduce transmission. At the same time, 70% thiophanate-methyl wettable powder can be used to control late blight, ring rot and other diseases.