On December 9, solstice, 14, 2016, the national corn industry technology system conducted a special investigation on the situation of ear and grain mold of corn acquired and stored in northeast China that year. This research covers 15 test station 75 demonstration county (farms) of 1348 farmers (cooperative), research content includes: planting varieties, sowing period, growth period, the local active accumulated temperature, harvest way, storage way, the current rate of grain moisture content, grain and grain mildew, hazard grade nine indicators, such as effective sample for 1287, among them, 442 in heilongjiang province, the representative area of 57441.6 acres; Jilin Province 421, representing an area of 16321.7 mu; Liaoning province 215, representing an area of 4,520 mu; There are 209 in Inner Mongolia, representing an area of 8729 mu. The research results are as follows:
一、Data results and analysis
1. There are many varieties of maize and the planting phenomenon in the cross area is still serious
Among the 1287 valid samples, there were as many as several hundred variety names, and there was a large yield gap in the same site. Many species require temperatures above or close to those of local activities. This phenomenon is relatively common in Heilongjiang province, jilin Province has also occurred. For example, Xinxin No. 1 is the second cumulative temperate zone variety in Heilongjiang Province, which has been planted in Keshan County, the lower limit of the third cumulative temperate zone in Heilongjiang Province. In Huinan County, Jilin Province, the annual accumulated temperature of local activities was only 2,750 ℃, but many farmers chose to plant tiannong No.9 variety with an effective accumulated temperature of 2,800 ℃.
2. The sowing time is suitable and the harvest time varies greatly from north to south
The sowing time of the first cumulative temperate zone in Liaoning, Jilin, Inner Mongolia and Heilongjiang is basically in late April, with a few in early May. The sowing time of the second, third and fourth temperate zone in Heilongjiang province was from the first half of May to the middle of May. In Liaoning province, the earliest harvest time was in late September; in Heilongjiang province, the fourth cumulative temperature belt was in mid-November, the latest; in other areas, it was mostly in early and middle October. The shortest growth period (sowing to maturity) is 104 days, the longest 155 days, other varieties growth period is mostly in 120 ~ 130 days, the overall growth period is longer, many varieties mature period has been close to the first frost period and even in the first frost period is still not complete.
3. Panicle and grain harvest coexist, and the storage methods are varied
The main harvesting methods were mechanical ear harvesting. 119 households adopted mechanical ear harvesting, accounting for 9.2% of the total. They were mainly concentrated in the third and fourth cumulative temperate zone of Heilongjiang Province. Other areas mostly use machinery to harvest ears, very few are artificial harvest. There are various storage methods, including open air stacking, simple shed, corn station, standardized storage facilities and drying storage. The latter two accounted for 469 households, accounting for 36.4% of the total. Among them, 55 households (cooperatives) in Heilongjiang province dried and stored, accounting for 12.4% of the surveyed households. Jilin province has the largest number of simple storage facilities, 254 households, accounting for 60.3% of the surveyed households in the province. Liaoning province a variety of ways coexist, and Inner Mongolia is mostly open stacked.
4. At present, the grain water content of corn is generally higher, especially in Heigi and Heilongjiang provinces
Taking mu unit as the weighted average base, the weighted average water content of corn seeds in the three provinces and one region of Northeast China is 27.9%. The weighted average grain water content with simple storage facilities was 29.2%. 27.1% did not have simple storage facilities. The highest grain moisture content in Heilongjiang was 30.0%, followed by 25.9% in Jilin, 23.3% in Liaoning and 19.5% in Inner Mongolia. Inner Mongolia autumn and winter monsoon less rain, conducive to corn seeds to reduce water content.
5. Mildew rate is generally higher in Jilin than in other provinces
More than 90% of the samples were investigated by mixing ear rot rate and grain mold rate. Therefore, the mold rate could only be calculated using mu unit as the weighted average base. The weighted average mold rate of the samples in one district of three provinces in northeast China was 0.73%.
The reasons for the higher grain mildew rate in jilin province may be as follows :(1) the temperature drop in autumn is slower than that in heilongjiang province, and the higher temperature leads to grain mildew; (2) It was rainy in autumn this year, and ear rot of maize occurred seriously in the field before harvest. (3) The grain moisture content was significantly higher than that of Liaoning and Inner Mongolia, which increased the possibility of mildew in storage period. In Heilongjiang province, the grain moisture content was higher, but the mildew rate was lower, mainly because 12.4% farmers took drying measures to reduce the occurrence of mildew.
The weighted average mildew rate with simple storage facilities was 0.74%, while that without simple storage facilities was 0.73%. There was no significant difference in mildew rate between the two, which was similar to the deviation of grain moisture content. There are no simple facilities for storage in Inner Mongolia, which are all stacked in the open air, but the mildew rate is low. The reasons for this phenomenon are firstly that the air humidity in Inner Mongolia in autumn and winter is lower than that in Jilin Province. The average cumulative temperature of the 19 demonstration counties surveyed in Jilin province in 2016 was 2,955 ° C, while the average cumulative temperature of the 10 demonstration counties surveyed in Inner Mongolia was 3,202 ° C, 247 ° C higher than that of Jilin. Thirdly, more than 70% of the corn area in Inner Mongolia was cultivated with film mulching, and the maturity stage was earlier than that in Jilin. However, the activity accumulation temperature of the two main cultivars was similar, so the moisture content and mildew rate of corn grains in Jilin province were significantly higher than those in Inner Mongolia.
二、suggestion and countermeasure
At present, most of the corn varieties are not suitable for mechanical grain harvesting. The forced machine not only has a high rate of breakage, but also is easy to increase the rate of mildew without modern drying and storage facilities. Therefore, agricultural administrative departments should closely monitor the moisture content and mildew rate of corn grains and guide farmers to take targeted preventive measures.
1. Strengthen variety management to avoid cross - area planting. It is suggested that farmers choose the early maturing varieties with a temperature above 200 ° C lower than the accumulated temperature of local activities. The seed management department should provide technical guidance and standardized management for seed distributors and seed companies.
2. Encourage purchasing and stockpiling enterprises to accelerate the purchase of qualified corn for sale. The state should adopt various policies to support the purchase and storage enterprises to accelerate the purchase of qualified corn.At the same time, it is suggested that farmers manually pick out mildewed ears of fruit to reduce the loss of continuous mildewed corn. In order to avoid the occurrence of mildew caused by the accumulation of snow in the open air, measures should be taken to cover the corn piled up in the area with frequent snowfall in winter.。In the future, in the development of mechanical grain harvesting technology, should invest in the construction of corn threshing and modern drying storage facilities.
3. Breed early maturing, dense-tolerant and stress-resistant varieties. The main factor leading to maize mildew is that the growth period of most varieties planted in current production is relatively long and the grain moisture content is high and the grain breakage is serious at harvest time. Secondly, the varieties had poor insect resistance. The bracts, ears and grains were chewed, which led to rotten grains and then to mildew. The third reason is that the short bracts of the varieties suffer from much rain in the late growth period, and the ear is easy to be flooded, leading to mildew. Fourth, the variety is not resistant to ear rot. In the future, the selection and breeding of early maturing and dense-tolerant varieties should be put in the first place, leaving enough time for stalk dehydration in the later stage of maize. Second, the length of bracts in ear should be taken into consideration. At present, American germplasm is the main species of short bracts. In case of abnormal climate, the bracts become shorter, and rain can easily enter the ear, leading to the breeding of mold. In order to improve the resistance of American germplasm, local germplasm should be added. Thirdly, we should pay special attention to improve the resistance to ear rot of cultivars under the condition of seed harvesting. Fourthly, the ability to resist insects at ear stage should be taken into account.
4. Improve grain storage methods. We will promote standardized grain storage and post-drying grain storage methods, and guide rural households to shift grain storage from open-air stacking to scientific storage. We will establish a monitoring and early warning mechanism for grain purchases and stockpiles. Through the comprehensive analysis of meteorological information, the investigation of maturity stage, the prediction and determination of grain moisture content, the reference information is released in advance to professional cooperatives, large grain growers and grain collecting and storing enterprises.
