□ Yan Ying, our reporter

In mid-October, walking in villages across Jiangsu, large tracts of rice paddies have turned yellow。Breeze blowing, a slight rice fragrance, the delightful autumn harvest is just around the corner。However, the reporter found during the visit that in the memory of many rural elderly people, it seems that the autumn harvest should be earlier。Why is the current autumn harvest later than when I was a child？Will the late autumn harvest affect the crop yield？

The autumn harvest is late

"If there is no major wind disaster, the average yield of rice per mu this year is no problem.。On the afternoon of October 8, Yin Yang Town Yin North Village in Qidong City Herun family farm 850 acres of golden rice fields, farmer Chen Zhengyu told reporters after the rice production forecast, last year's autumn harvest rice into the storage unit yield of 1250 catties, higher than the city's average yield of 180 catties, this year is expected to be harvested in early November。

Preparations for the autumn harvest are now underway across the province。Rice planting in Pukou District, Nanjing 3.430,000 mu, is expected to begin harvesting in mid-to-late October, large-scale harvest to early mid-November。On the morning of October 10, Shao Lichang, the person in charge of the Pukou District Gumanman planting professional cooperative, went to the Orchid pond high-standard farmland to check the rice growth as usual, and the agricultural machinery for autumn harvest was parked in the open space of the cooperative, and the rape and wheat seeds for autumn planting were stacked in the warehouse。

"This year, the Mid-Autumn Festival National Day holiday encountered a few cloudy days and low temperatures, and the rice did not grout in those days, delaying the growth rate, and I saw that the autumn harvest would be a little later.。Shao Lichang walked in the rice field, while saying, holding up a bunch of rice ears, pinching the top and bottom of the rice grain with his fingernails, and the bottom of the rice grain then emerged white pulp。He told reporters, "The ears of rice gradually mature from the top to the bottom。You see, the top of this grain is ripe, it is hard to pinch, but the bottom particle is still white pulp, that is, it has not grown well。The little stalks under the ears of the rice are also green, not yet yellow。I go to the fields every day。In Orchid Pond, 2,000 mu of indica hybrid rice is expected to be harvested from October 15 to 20, and 2,000 mu of japonica rice is expected to be harvested in early November。”

With the rice growing fuller, the autumn harvest is just around the corner。However, the reporter found that the autumn harvest is not only a little later this year, but the overall time seems to be later than 20 or 30 years ago。"The rice variety is Yongyou 6711, which is expected to be harvested on October 20, with an mu yield of about 1,500 jin.。If the weather is good, the plan is to plant wheat alongside the harvest。October 9 afternoon, Siyang County agricultural technology extension center senior agronomist Jiang Xuezhong is Chengxiang street Buhu village Buhu family farm measurement。He told reporters that the autumn harvest had indeed been delayed in recent years。"Ten years ago, the week after the National Day was a busy time, we basically guided farmers in the fields to harvest and grab seeds, and the autumn sowing will generally not exceed October 5 at the latest.。At present, we are still guiding farmers to prepare agricultural machinery and wheat planting preparations for the autumn harvest, and the on-site meeting has been postponed to October 10-15。”

"Now the autumn harvest is indeed a little late, and this" late "probably began at the end of the last century。Xu Ke, a professor and doctoral supervisor at the College of Agriculture of Yangzhou University, told reporters that in the 1990s, a week after the National Day, farmers generally began to harvest rice, and the autumn harvest scene appeared。After the change of autumn harvest time, during this period of farming, soil moisture in the field and the occurrence of plant diseases and pests are mainly monitored, and necessary irrigation and plant protection operations are carried out。"In terms of scientific research, during this period of time, one is to focus on the determination of leaf, grain and other morphological and physiological characteristics of rice at maturity, and monitor the aging status of rice;Second, the theoretical yield of rice was measured, such as panicle number per unit area and grain number per panicle。”

Why later than usual

Why is the autumn harvest late？The reporter conducted an interview。

Siyang County is a large agricultural county, rice planting area of 540,000 mu, wheat 720,000 mu。Jiang Xuezhong said that in Siyang, the late autumn harvest is mainly related to rice varieties and planting methods。"After the variety renewal in these years, the rice growth period is generally longer, and Siyang once promoted japonica rice for a period of time, and the japonica rice growth period is longer, which leads to the delay of rice harvest.。At present, the area of hybrid indica rice in the county is about 60%, and that of japonica rice is 40%。In the past, the ripening period of rice in Siyang was probably around the National Day, no more than October 10, and now most of it begins to mature around October 20。In terms of planting methods, the original family planting is mostly manual planting, and now the land is transferred in a large area, and 70%-75% of the rice fields are planted by machine。Since the age of manual transplanting is one month, and the age of mechanical transplanting is limited to about 20 days, the seedling rearing time is delayed by 10-15 days, so the maturity time is delayed accordingly。”

"Because the yield of hybrid indica rice had reached a plateau at that time，The yield of japonica rice increased gradually due to breeding progress，In addition, people in the Taihu basin like to eat rice，In the mid-1990s，Jiangsu has launched a plan to "press indica and expand japonica"，Area of indica hybrid rice，Expand japonica rice planting，于是，The province's rice planting pattern has undergone major changes (the province's perennial rice planting area is about 33 million mu，Previously, the planting area of hybrid indica rice had reached half，Only about 4 million acres in recent years)，All of southern Jiangsu has been riceized。The harvest of hybrid indica rice generally begins at the end of September, and many farmers on vacation are busy with the autumn harvest of indica rice during the National Day holiday。The japonica rice has a strong resistance to low temperature, and the growth period can be 15-30 days long, so everyone will feel the autumn harvest becomes late。Dr. Lu Chuangen, a researcher at the Food Crop Research Institute of the Provincial Academy of Agricultural Sciences, analyzed that the reason for the "autumn harvest is later than when I was a child" is first related to changes in the farming system and cultivation methods。In addition to the "decrease in indica and increase in japonica" of rice types, since the beginning of the 21st century, the area of direct seeding rice has been expanding year by year, which will also lead to the delay of rice maturity in a large area。"In the past, it was seedling cultivation and artificial planting, and the seedlings had grown for a month before planting, while the live rice was sown after the harvest of summer crops such as wheat, which was equivalent to being planted late, and the maturity and harvest period would inevitably be later.。”

"Climate is another factor。Lu Chuangen looked at the temperature data of 70 years in China and found that the average increase was 0 per 10 years.26 degrees Celsius。"On the one hand, temperature increase provides warm and light conditions, which is conducive to the continuous growth of rice in the later stage.On the other hand, the optimal planting time of wheat and rape is also appropriately delayed, because if it is still planted according to the original time, rape and wheat may advance bolting and ear differentiation, and the risk of freezing damage will increase due to reverse spring cold。Therefore, in order to reduce the risk of freezing damage to wheat and rape, it can not be sown too early。In addition, in the past ten years, mechanized harvesting and mechanized sowing have been popularized, saving farm operation time, which objectively give time to "elderly rice" (that is, the rice continues to stay in the field after maturity, so that nutrients are further transported to the grain)。”

"The first is that the whole growth period of rice varieties currently in production has become longer。Scientific research and production practice showed that the yield and quality of rice varieties with longer growth period were improved。The widespread application of these varieties has led to a continuous delay in the harvest date of rice。In the 1990s, the harvest period of the varieties widely promoted in Yangzhou was generally in early and mid-October, and the current varieties were generally in mid-late October, or even early November。Secondly, farmers generally have the habit of "aged rice" in production, and the autumn harvest will be later。Xu Ke analyzed that the delay of autumn harvest is also related to the level of fertilizer and water management and agricultural mechanization in rice production。目前，Rice growers seek higher yields，Generally, the production management mode of applying large amounts of nitrogen fertilizer and flooding irrigation is adopted，The nitrogen metabolism of rice was still at a high level after flowering，Carbon metabolism is at a low level，There is a problem with the carbon to nitrogen ratio，The plants are green and late in ripening，If you harvest early, it will lead to lower yield and lower quality。"In terms of harvesting methods, the artificial harvest period was longer in the past, and the operation time after the improvement of agricultural mechanization level was short, the harvest calendar time was shorter, and it was still too late to postpone a little harvest.。”

How to deal with late harvest

The late harvest is a good thing or a bad thing？Whether measures need to be taken to deal with it？

"The delay in the autumn harvest has both advantages and disadvantages。Lv Chuangen analysis，On the plus side，"Green straw and yellow seed" after japonica rice ripening，non-lodging，Late harvesting and "aging rice" can improve rice yield and rice quality，同时，The moisture content of the rice will continuously decrease，Save sun-drying time and some manual input;The disadvantage is to increase the time of rice in the field，Increase the risk。

"The risk is especially for direct seeding rice。There is a concept of "safe ear" in rice cultivation，即，Such as in Nanjing area，The heads must be in full bloom by September 18，otherwise，According to the year-round temperature，There's a one in five chance of cold temperatures，Affect flowering and setting，The grouting stage is susceptible to "cold dew wind"，Inadequate grout and yield reduction。The risk of direct seeding rice is increased due to late planting, while the machine-transplanting rice is basically risk-free because it is already 20 days old at the time of planting。In addition, a late autumn harvest may affect subsequent crops and annual yields。”

"In addition to improving the rice harvest to a certain extent, the late autumn harvest will also have a greater impact on the next crop of wheat sowing and growth.。Xu Ke analyzed that wheat needs to form strong seedlings before overwintering to resist the cold winter, but the formation of strong seedlings requires more accumulated temperatures above zero to be achieved。"Generally speaking, after the suitable planting period of wheat (each region has its own suitable planting period), the later the sowing, the more unfavorable the wheat growth and yield, and it is difficult to achieve high yield.。Lu Chuangen reminded that the next crop of Jiangsu rice is mostly rape and wheat, and the best planting time for rape is generally from October 25 to October 30, and wheat needs to be sown before the start of winter (or November 10)。"For machine-transplanting rice, the crop is fine, for live rice, the crop is relatively tense, because after the rice is harvested, the land has to be tilled and other farming activities, and the time is very tight.。”

So, what can be done to reduce the disadvantage of a late harvest？

In view of the delay of wheat sowing, Jiang Xuezhong suggested that the quality of sowing can be improved, the amount of seed can be appropriately increased, and the base fertilizer should be fully applied in field management。Lu Chuangen put forward suggestions from the planting of rice: First of all, rice planting should minimize the use of direct seeding, and use machine transplanting to avoid late crop。Secondly, in some areas where the field is small or the terrain is not suitable for mechanical interpolation, it is necessary to choose rice varieties with shorter growth period as far as possible, otherwise, in the autumn harvest season, on the one hand, the crops in the back are waiting for the stubble, but the rice has not been sufficiently irrigated, and the early harvest suffers losses。"Because rice is of high quality and high price，Higher economic value，To cater to the market preference of the Yangtze River Delta region，Some farmers in Nanjing Liuhe prefer to plant high-quality late japonica south japonica 46 with a longer growth period，From the perspective of annual yield and planting risk，It is suggested to choose rice varieties with shorter growth period，如，It belongs to the high quality "early and late Jing" Ningxiangjing No. 9 and Nanjing 5055 with short growth period。However, if we want to calculate the annual economic account, the increase and decrease of high-quality rice income depends on how farmers choose to choose。”