Rice lodging affects yield and rice quality, how can it be prevented?

Rice lodging refers to the phenomenon in which upright-growing crops become slanted in patches, or even the entire plant lies prostrate on the ground, due to natural factors such as wind and hail, heavy rain, or external forces. Lodging can reduce crop yield and quality and make harvesting difficult. What effects does rice lodging have on yield and rice quality? How can it be prevented?

1. What effects does rice lodging have on yield and rice quality?

Many articles have analyzed the effects of rice lodging on yield and explained the several major causes and types of rice lodging, but few have discussed how great the impact is on rice quality.

1. Effects of lodging on yield

After rice lodging, the empty grain rate increases, green heads increase, and yield decreases. From the perspective of yield components, lodging mainly causes a substantial decrease in seed-setting rate and 1000-grain weight, among which the seed-setting rate has a greater impact on yield.

2. Effects of lodging on rice quality

When rice lodges, the head rice rate decreases significantly, and the earlier the lodging occurs, the greater the decrease, and the head rice rate drops even more. At the same time, the impact of lodging on rice quality is also comprehensive; after lodging, most quality indicators of rice (amylose content, gel consistency, etc.) showed varying degrees of decrease.

In the selected green heads and chalky grains, the chalky grain rate and chalkiness degree increase noticeably

As for appearance quality, it may have little effect on grain length, grain width, and length-to-width ratio, but the chalky grain rate and chalkiness degree are the weak points; the milled rice must undergo color sorting, and the remaining head rice rate is then pitiful.

The above understanding is supported by data. A study used the mid-season two-line hybrid rice Liangyoupeijiu and the mid-season japonica rice CY6 as materials and carried out lodging treatments at different stages during the grain-filling period. The results showed that for CY6 and Liangyoupeijiu, for every 1 day earlier that lodging occurred during the grain-filling period, it caused 2.71% and 2.66% yield loss respectively, reduced the seed-setting rate by 1.8% and 2.1%, lowered the 1000-grain weight by 0.32 and 0.27 g, reduced the head rice rate by 0.097% and 0.155%, increased the chalky grain rate by 0.13% and 0.27%, increased the protein content by 0.021% and 0.024%, and lowered the eating quality of the rice.

In addition, there is another survey compiled from the 21 years from 1990 to 2010 on japonica rice varieties planted in Heilongjiang Province, which reached a conclusion: lodging at the milk-ripe stage reduced yield by 35-50%, and all the rice was of poor quality; lodging at the dough-ripe stage reduced yield by 10-15%, decreased the 1000-grain weight by 1.2-2.5%, and increased chalkiness degree.

Therefore, ensuring that rice does not lodge is a prerequisite for obtaining high yield and high quality in rice. So how can lodging be prevented?

2. How to prevent rice lodging?

1. Scientific fertilization

For planting high-quality rice, it is generally recommended not to apply urea; be sure to correct the old habit of applying more just because urea is cheap. Applying too much nitrogen fertilizer easily makes the seedlings grow vigorously and weakens the plant's lodging resistance and disease resistance. It is recommended that base fertilizer and tillering-stage topdressing be mainly compound fertilizer, and that silicon-zinc fertilizer be added at the tillering stage to enhance the stress resistance of the rice plants. After draining the field and reflooding, apply a heavy potassium fertilizer topdressing once (15-20 jin). From the flowering stage to the grain-filling stage, combined with pest and disease control, spray potassium dihydrogen phosphate or amino acid (humic acid)-containing foliar fertilizer, so the rice grains are fuller and the rice quality is better.

For rice to resist lodging, attention must be paid to safe fertilization, nutrient balance must be considered, and formula application must be carried out according to the fertilizer requirements of rice.

2. Choose varieties with stronger lodging resistance

Choosing high-quality rice varieties with relatively strong lodging resistance is helpful for preventing or reducing the degree of lodging. A variety with good rice quality, strong lodging resistance, and high yield is almost nonexistent, but you can choose one with excellent rice quality, relatively good lodging resistance, and relatively stable yield, whose overall benefit is better than ordinary super rice. For varieties with particularly excellent rice quality, the yield is mostly average and lodging resistance is not strong, so it is recommended to strengthen water and fertilizer management.

3. Pay attention to pest and disease control

In recent years, there have been many cases of lodging caused by pests, diseases, and weather. I remember that last year a farmer encountered bacterial leaf streak for the first time and did not know how to control it (some heard others say it would not affect yield, or mixed pesticides randomly for control, or used the wrong spraying method), and by the grain-filling stage, due to cloudy and rainy days and strong wind, it easily lodged, and leaf streak disease affects the photosynthesis of rice leaves, causing relatively severe yield loss. In recent years, the damage from the striped stem borer has been severe, and there have also been major outbreaks of rice planthoppers in the past, all of which easily cause the seedlings to lodge. For specific pesticide use, please refer to the Rice Knowledge Mini-Class and consult local agricultural technical service personnel.