Potato watering: the method matters
From the time the potato seedlings push through the soil until flowering, generally do not water; let the plants go through a water-restriction seedling-hardening period, and only give a little water in cases of extreme drought. Cultivation experts have run many comparative trials on loam soil with good water retention, and potatoes given water-restriction seedling hardening yielded 20%-25% more than those watered without seedling hardening. This is because the root mass of water-restricted, hardened seedlings is 2.5-3 times that of watered, non-hardened plants. Only with a well-developed root system can potatoes absorb more nutrients and water from the soil and synthesize and accumulate more photosynthetic material. Potato seedling hardening prevents excessive vegetative growth from consuming nutrients, produces short internodes, thick stems, thick leaves and a compact plant, and develops into strong seedlings with greater resistance to wind and rain, lodging, and pests and diseases.
Begin watering potatoes at the early flowering stage. From early flowering until the stems and leaves stop growing, tuber growth is at its greatest and the plant's water requirements are also very high. On the other hand, the nitrogen, phosphorus, potassium and other inorganic elements that potatoes need for growth must all be dissolved in water before the roots can absorb them; if the soil lacks water, no matter how abundant the nutrients are, the plant cannot use them. Soil moisture content should generally be kept at 60%-80%.
At this time, because water is plentiful, potatoes often also grow excessively in the mid-to-late period, consuming nutrients and lodging, which reduces yield. For this reason, chemical regulation must be used. When potato plants are 50-55 cm tall, spray 50 g of 15% wettable paclobutrazol powder per mu, then water 4 days after application, which can achieve a clear height-control effect.
Stop watering about 10 days before potato harvest, which can improve quality and make the tubers more storeable.