During the period between the “equinox†and “cold dewâ€, the cold air in the north frequently flies southwards, and the average daily temperature is often below 22°C for more than 3 days in a row, accompanied by strong winds and rainy weather. Farmers usually call this kind of weather “cold dewâ€. wind".
One of the effects of cold dew on hybrid late rice is poor heading and necking. Hybrid late rice is affected by the parental line of the sterile line, and the necking phenomenon often occurs during heading. The later the sowing, the lower the temperature, the longer the low temperature, the more serious the package neck, especially the hybrid rice neck. The second is poor flowering loose powder, resulting in empty shells. Hybrid late rice is extremely sensitive to temperature during flowering, especially before and after full bloom, if there is a low temperature, there will be a large number of closed flowers, hybrid late rice pollen mother cells in the meiosis phase of cold dew, bad pollen development, infertility Increased pollen grains will form a large number of empty shells without insemination. It has been observed that when the average daily temperature of heading and flowering stage of the indica hybrid combination is lower than 23°C, the empty shell rate will increase significantly. Third, the speed of grouting was blocked. The cold and dew during the filling period will reduce the photosynthesis of hybrid late rice, affect the grain filling, decrease the grain weight, and increase the empty grains. Especially when the temperature is below 20°C during the milk ripening period, it will cause poor grain development and dry matter. Accumulation was reduced and a large amount of eucalyptus grains and empty husks were formed, affecting the yield of hybrid late rice.
One of the measures to defend against cold dewness is to adopt a reasonable crop layout and select suitable varieties for the growth period to avoid cold damage during heading and flowering, based on the characteristics of low temperatures occurring throughout the region. The second is to supplement potash fertilizer to enhance cold resistance. Production practices have proved that the appropriate addition of P and K fertilizers to hybrid late rice has special effects on the defense against low-temperature chilling injury. In particular, cold-sweeping fields, sandy fields, and plots where organic fertilizers are applied less, the effect of supplemental potassium fertilizers is more pronounced. In areas where there is sufficient ash, we can control the heading and flowering stage. 100-150 kilograms of plant ash per acre is applied to the leaves in the morning when the dew is not dry. This counteracts chilling, reduces pods and increases grain weight. Good effect. If the cold dew wind is encountered during the heading stage, the combined weather forecast can be applied to the leaves for 5 to 6 days before the cold dew wind comes in. The primary potassium dihydrogen phosphate is sprayed on the leaves. Each time, 100-150 grams of potassium dihydrogen phosphate is used per acre. Water 50-60 kg, evenly sprayed on the leaves after 4 pm, can increase the cold resistance, increase the seed-setting rate and 1000-grain weight, the effect is more significant. The third is to deepen the water. In the deep water above 5 cm before the cold dew wind comes, the temperature of the field surface and panicle can be increased by 1°C~2°C, drained the next morning after irrigation, and the river or pond water with higher temperature can be recharged in the evening to maintain the heat preservation effect. The fourth is to spray the "92" hormone. Before the arrival of the cold dew, the “Ninety-Two O†should be sprayed on the hybrid late rice fields that are not expected to be full-fledged. The spraying time is 5~7 days before the forecast, and the concentration is 20~30ppm. Ninety-two O" 1 to 1.5 grams, spraying 60 kg of leaf on the water can not only reduce the degree of neck wrapping, but also promote the safety of hybrid late rice. Fifth, artificial pollination. When the late hybrid rice meets the cold dew wind, it can be tossed with a small bamboo pole or pulled with a rope every day to make the flag leaf vibrate and to promote the cracking of the anther and conduct auxiliary pollination, which can increase the seed setting rate by more than 20%.