Maize Genomics and Genetics 2025, Vol.16, No.3, 149-166 http://cropscipublisher.com/index.php/mgg 161 and replaced every 5 days, and the straw with eggs is burned in a centralized manner to reduce the number of eggs in the field; on the other hand, once the signs of damage by armyworm larvae are found in the field, high-efficiency and low-toxic biological pesticides or botanical pesticides are immediately sprayed for prevention and control (such as directional spraying of preparations containing chlorpyrifos or phoxim) to promptly curb the spread of insect pests in the early stage (Wang and Huang, 2024). Through the above measures, corn borers and armyworms were effectively controlled in the demonstration field, and no significant loss of fresh ear yield was caused. 6 Problems and Challenges 6.1 Impact of abnormal climate on growth cycle and yield Significant abnormal climate occurred during the experimental year, including continuous drought and low temperature in spring and high temperature and little rain in summer. Continuous sunny and dry weather and low temperature in March and April caused poor soil moisture, slow recovery of ground temperature, slow and uneven emergence of fresh corn, and early growth of seedlings was hindered; some plots lacked seedlings due to lack of effective irrigation. Entering the middle and late growth period (late July to mid-August), it encountered continuous sunny and hot weather, and the maximum daily temperature was above 35 ℃ for a long time. This abnormally high temperature period coincided with the flowering, pollination and grain filling period of corn. High temperature stress led to reduced pollen vitality and pollination fertilization rate, poor silking of female ears, accelerated filling rate and shortened duration, and ultimately insufficient grain filling. High temperature and drought also aggravated plant water stress. Functional leaves of corn plants in some fields showed premature aging, and the phenomenon of empty stalks and bald grains increased, which seriously affected the formation of yield. The direct consequence of high temperature and drought stress is the abnormal changes in the growth cycle and yield of fresh corn (Liu et al., 2022). Under the influence of the rapid rise in temperature in the later period, the differences in the growth period of the participating varieties were narrowed, and the full growth days of most varieties tended to be consistent (about 111 days), and the maturity period was too concentrated. In particular, except for the early-maturing 'Jinyin 208' and 'Xuetian 7401', the maturity period of the remaining 8 varieties arrived almost at the same time, reflecting that the abnormally high temperature accelerated the maturity of corn and ended the filling in advance. Although remedial measures such as drought-resistant irrigation were taken during the experiment, the yield and quality of crops were still significantly affected. It was calculated that the high temperature and drought caused the measured yield of fresh corn to be 13.0%~20.9% lower than the normal level, the quality of commercial ears decreased, and the fullness of the grains was poor. At the same time, the unfavorable climate caused different batches of corn to mature at the same time, which not only increased the pressure of harvesting and processing, but also caused the time for fresh ears to be put on the market to be too concentrated, which was not conducive to the peak supply market (Bheemanahalli et al., 2022). 6.2 Threats to quality from frequent pest and disease outbreaks During the trial, the high incidence of major local corn pests and diseases also posed a threat to the yield and quality of fresh corn. Among them, corn borer is one of the most common and most serious pests. Field surveys found that signs of corn borer damage appeared many times during the growth period of corn, such as larvae eating heart leaves, male ears and leaves, and boring into the stems to cause pith cavities. Plants attacked by corn borers often show weak growth, and in severe cases, the stems break and fall or the cobs are damaged. More importantly, corn borer larvae can also invade female ears and eat grains, causing partial rot of the cobs and grains. Affected by this, the integrity of the ear shape of fresh corn was destroyed, the ears and grains were not arranged evenly, some ears were missing grains and worm holes, and the fullness of the grains decreased significantly. Insect pests directly reduce the appearance quality and commerciality of commercial corn ears. The damaged ears are poor in appearance and easy to mold, and the market acceptance is reduced. At the same time, the flavor and taste of the ears deteriorate after being fed by corn borers or infected by pathogens, which is not conducive to maintaining the sensory quality of fresh corn (Tang, 2024). According to statistical analysis, if corn borers are not controlled in time, the yield of fresh corn may be greatly reduced, and even the harvest may be completely lost in
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