What to Do About Hollow Heart in Radishes? Causes and Control Measures in Early Spring

 Radish hollow heart, also known as pithiness, is the phenomenon in which a cavity forms in the central part of the xylem of the fleshy root.

1. Causes: (1) Related to variety. Varieties with large parenchyma cells in the fleshy root have poor root density and are prone to hollow heart. (2) Related to soil texture. Radishes grown in soil with excessive sand tend to develop hollow heart earlier than those grown in loam or clay. (3) Improper water supply. If moisture is even during the early growth period but drought occurs later, especially during the fleshy root formation stage, soil water shortage hinders growth, resulting in hollow heart. (4) Unreasonable planting density. Under wider plant and row spacing, the fleshy root grows too quickly, and the growth of leaves and roots loses balance, so the organic nutrients produced above ground are insufficient to supply the needs of the expanding fleshy root below ground, making hollow heart likely. (5) Unreasonable fertilization. Especially when topdressing is too late and too heavy in the later stage, combined with improper matching of fertilizer types, applying too much nitrogen fertilizer makes the above-ground part of the radish grow too vigorously and the root becomes excessively large, causing hollow heart. (6) Harvesting too late or bolting having already occurred. (7) Wounds such as cracked skin and cracks caused during harvest, storage and transport increase respiration and cause excessive nutrient consumption, leading to hollow heart. (8) Storage temperature too high. The suitable storage temperature for radishes is 1-3 degrees; above 3 degrees they readily sprout and grow, leading to hollow heart. (9) Storage environment too dry. The ideal air humidity is 90-95%; when it is below 90%, radishes continuously lose water, making the tissues soft and causing hollow heart. 2. Control measures: (1) Choose varieties that are not prone to hollow heart and have a high degree of fleshy root density. (2) Plant at a reasonable density. (3) Fertilize scientifically. For spring radish fertilization, adopt the principle of giving priority to base fertilizer and supplementing with topdressing, and pay attention to the rational combination of the three elements nitrogen, phosphorus and potassium. (4) Supply water evenly. Prevent the soil from being too dry or too wet, and maintain soil moisture at 70%-80%, especially in the later growth stage of radishes, when the soil must not be too dry. (5) Harvest at the right time. (6) Chemical control: generally half a month before harvest, spray once with a 50mg/kg gibberellin solution (do not spray too early, to avoid inhibiting fleshy root expansion), or spray once with a 10mg/kg naphthaleneacetic acid solution, which neither affects fleshy root growth nor prevents hollow heart, and delays maturity. If when spraying 10mg/kg naphthaleneacetic acid, 5% sucrose and 5mg/kg borax solution are added and the three are mixed and sprayed, the effect of preventing hollow heart is even better. (7) Minimize mechanical damage such as broken skin and breakage during harvest and transport. (8) Pay attention to the temperature and humidity of temporary storage.