What are the control methods for early heading in rice?

This year, the Yangtze River and Huai River basins have experienced persistent drought with little rain, causing severe impacts on agricultural production. In July-August, rice in the rice-growing areas north of the Yangtze River and in the Huai River basin showed "early heading" to varying degrees. Field performance: 2-3 early heads per hill, differing from late-developed tillers by more than 7-10 days, clearly showing "second flush heads" or "third flush heads". To make up for the losses caused by "early heading" to field production as early as possible, the causes of early heading are analyzed below, and rescue methods are proposed.

The length of the rice seedling age is closely related to the early heading phenomenon. Seedlings of moderate age have strong rooting ability; seedlings with a long seedling age do not root as fast as tender seedlings; and old seedlings with a long seedling age and poor management have declined rooting ability, and both establishment and tillering are slow. In particular, for early rice and continuous-cropping late rice, one third or more of the growth period is spent in the seedling bed, so sowing should be appropriately early, and the seedling age is accordingly extended. But if the seedling age is too long, especially for some varieties whose suitable seedling age range is relatively strict, exceeding the suitable seedling age will cause them to enter reproductive growth early; the total leaf number of the main stem decreases, and economic traits deteriorate. When such overage seedlings are transplanted into the field, they will head too early, resulting in small heads and few grains. The suitable seedling age varies by variety. Generally speaking, the suitable seedling age for early-maturing varieties is no longer than about 25 days, for mid-maturing varieties no longer than 30 days, and for late-maturing varieties no longer than about 35 days. Strong seedlings of suitable age, not overage, can prevent early heading and are the foundation of high rice yield.

Control methods for early-heading rice seedlings: generally, overage seedlings should be eliminated as much as possible. If there are not enough seedlings and they must be used, then in addition to heavily applying the starter fertilizer in the seedling bed, applying more basal fertilizer at harrowing in the main field, and applying quick-acting fertilizer early, the method of root-pruning and seedling-hardening can also be used to suppress excessive growth. The method is: about 5-7 days before transplanting, lift the seedlings with soil, then place them neatly in the original spot or after slight shifting, apply quick-acting chemical fertilizer before lifting the seedlings or after arranging them, and after arranging them irrigate with one cun of water to protect the seedlings, without dehydrating until transplanting. After seedling-hardening, aboveground growth is temporarily suppressed and leaf color fades slightly, but after the roots are temporarily cut and suppressed, more new roots can grow, which is beneficial for transplanting, greening, and growth in the main field. Seedling-hardening can be applied to both early rice and long-seedling-age late rice seedlings. Of course, it is best to properly plan the seedling-raising method in advance; for some late-crop fields whose seedlings are at risk of becoming overage, the two-stage seedling-raising method may produce better results.