High-yield Cultivation Techniques for Indica Hybrid Rice Z You 272 Grown as Middle-season rice+Ratooning Rice

Yunhua ZHANG,Aiping MAO,Houqian WU,Jianzhong ZHU,Xiaoming PENG

1.Sichuan Luzhou Taifeng Seed Co.,Ltd.,Luzhou 646000,China;

2.Luxian Seed Management Station,Luxian 646100,China;

3.Luxian Bureau of Agriculture,Luxian 646100,China;

4.Luzhou Grain and Oil Crops Station,Luzhou 646000,China;

5.Xuyong Plant Protection and Quarantine Station,Xuyong 646400,China

Responsible editor:Nanling WANG Responsible proofreader:Xiaoyan WU

Luxian County is located in southeastern Sichuan Basin,its terrain is mainly dominated by shallow hill.The annual mean temperature is 17.8 ℃,annual mean rainfall is 1 100 mm,annual mean sunshine hours are 1 368.8 h,and the annual frost-free days are 340 d.Rice is the most important crop in Luxian,the perennial planting area of middle-season rice is 3.8×104hm2,and total yield is 32.23×104t.Luxian is also a suitable region for middle-season rice+ratooning rice growth in Sichuan Province[1],and the annual area of middle-season rice + ratooning rice is 2.7×104hm2and the yield is 5.27×104t in the county.

Z You 272 is a combination of hybrid rice mated by sterile line Z7A and restoring line R272 bred by Sichuan Shennong Biological Breeding Co.,Ltd.,which authorized by Sichuan Crop Variety Approval Committee in 2007 and by Chongqing Crop Variety Approval Committee in 2010,the total growth period is 149 d.In 2009,the average yield of Z You 272 grown as middle-season rice in Luxian was 10.29 t/hm2,and the average yield of its ratooning rice was 3.69 t/hm2.It was known that the rice was delicious with fragrance.Because Z You 272 not only had the advantages of early sowing,early transplanting,early maturity and high yield which middle-season rice owned,but also had the features of low-node tillering,early seedling,multiple shoots and multiple panicles which also middle-season rice owned,which made good conditions for the growth and high yield of ra tooning rice[2].To explore highyield cultivation techniques for Z You 272 grown as middle-season rice+ratooning rice,based on the implementation of the High-yield Project for Grain,Cotton and Oil Crops created by Sichuan Province and Ministry of Agriculture of PRC,the study on the project of “The Breeding and Integrated Matching Techniques of a New Hybrid Rice Variety Z You 272 with High Yield and Good Quality” has been carried out since 2008,thus forming high-yield cultivation integration technology.From 2008,Z You 272 has been grown as middle-season rice + ratooning rice in Luxian and its integrated high-yield cultivation techniques have been popularized,and the total extension area has reached 4.47×104hm2,and the area of middleseason rice+ratooning rice was 3.06×104hm2.Through many years of application and extension,Z You 272 showed the features of high yield,strong regeneration capacity and fine rice quality,as one of the main popularized varieties,significant economic and social benefits were got from a large area of production,so it a awarded was Second Prize of Luzhou Science and Technology Progress in 2010.The high-yield cultivation techniques of middle-season rice+ratooning rice were summarized as follows.

High-yield Cultivation Techniques of Middle-season Rice

Sowing timely and breeding eligible multiple-tiller seedlings

Sowing time and seedling-raising methodsTo ensure the high-yield level of middle-season rice,and safe heading and high yield of ratooning rice,the way of rice dry seedbed should be adopted[3].The best period for sowing and raising rice seedlings in dry land in Luxian was from solar term of “rainwater” (about February 19) to the end of February or early March(before March 5),too early sowing may easily cause decayed seeds and dead seedlings,and too late sowing can hardly play the effects of early sowing and early maturity of main middle-season rice.

Soil preparation and bedding of seedbedSand vegetable field with flat land,fertile and loose soil was the best choice for seedbed of dry-raising seedlings.Winter fallow field was prepared about 30 d before sowing,then the following fertilizers were applied as much as 10 kg/m2rotten animal manure water and 0.2 kg/m2calcium superphosphate.2-3 d before sowing,ditches were dug to make bedding or pit seedling bedding based on 1.5 m bedding width and 0.5 m ridge or furrow width,moreover,there was fine soil,flat land and weed free.

Irrigating thoroughlyIrrigating thoroughly was the key to ensure early and even emergence of seedlings.Before sowing,clean water must be sprinkled to bedding profoundly until the bedding surface had standing water.Don’t use liquid dung or biogas slurry as bottom water,to prevent root and shoot burning.

The seed dressing with HanyubaomuThe seed dressing with Hanyubaomu was the key to prevent sheath blight of dry-raising seedlings,which had the effects of fertility,sterilization and strong seedlings.Before sowing,seeds must be soaked in clean water for about 10 h,then taking them out for airing until no added water.After that,the seed dressing was carried out according to the ratio of Hanyubaomu powder to seed weight of 1:3,it should be noted that the seed dressing must be even to avoid seed adhesion.If there was seed adhesion,Hanyubaomu powder should be added until loosening,then sowing.After stirring and mixing,the seeds should be broadcasted evenly at the seeding rate of 40-50 g/m2,then the seeds must be covered with fine soil and the thickness of fine soil was about 1 cm.

Seedbed weedingAfter covering seed,dry-raising seedlings herbicide“Han Yang Jing” should be sprayed on bedding surface according to the instructions of packaging bag to prevent grass disaster.The caution was that the herbicide can not be directly sprayed on the seeds to avoid herbicide phytotoxicity.

Covering membranes for thermal insulationAfter sowing,sticking and covering membranes should be followed,and around the seedbed the membranes should be pressed tightly to improve insulating power.Moreover,the following measures should be followed for the growth of seedlings:The first was temperature control based on the principles of emergence of seedlings under high temperature,growth of seedlings under appropriate temperature and seedling hardening under temperature reduction.Before two-leaf stage,don’t uncover the membranes; during 2-3 leaves stage,uncovering the two sides of the seedbed in fine days for good ventilating; after three-leaf stage,membrane uncovering should be carried out gradually for seedling hardening,thereby preventing seedling overgrowing; after four-leaf stage,membranes must be uncovered completely.The second was humidity control.After sowing,high temperature and humidity should be kept for emergence of seedlings; during 2-3 leaves stage,preserving moisture was more important; after three-leaf stage,if a few leaves curled,it meant to water.The third was disease prevention.After 2-3 leaves stage of dry-raising seedlings,sheath blight was common,and at the early stage of morbidity,1 000-fold fenaminosulf should be sprayed.The fourth was fertilization.After three-leaf stage,liquid dung should be sprayed once with every new leaf emergence to accelerate tillering and improve the quality of seedlings.

Transplanting timely

When seedling age was 30-40 d and leaf age was 4.0-4.5 leaves,seedlings should be transplanted timely,generally,during late March and early April after the steady rise of air temperature,seedlings should be transplanted to the field.Then the three-dimensional intensified cultivation[4]must be conducted,namely,the bedding was 1.5 m wide and had three rows,hill spacing each line was 50 cm×(27-33)cm,each hill had three grains and formed equilateral triangle with the side length of 9 cm,thus to ensure the planting hills of 6.0×104-7.5×104hills per hectare.

Nutrient and water management

Base fertilizer was mainly organic fertilizer,and appropriate P and K fertilizers were also used;for per hectare,15 t animal dung,750 kg superphosphate,450 kg ammonium bicarbonate and 150 kg potassium chloride must be applied per hectare.5 - 7 d after transplanting,150 kg/hm2urea must be broadcasted to promote early growth and quick tiller of grain seedlings,in the later period,fertilizers should be applied according to the growth potential of seedlings to prevent premature senility.Shallow water was suitable for transplanting seedlings,and inch of water was conducive to reviving; appropriate water was beneficial to appropriate tillering,and shallow water also benefited heading and flowering time,moreover,grain filling happened during the alternation of wetting and drying.

Comprehensively preventing plant diseases and insect pests

To ensure the safety of rice stem and the germination ability of regeneration buds,the monitoring of diseases and pests should be strengthened,and the prevention of the following plant diseases and insect pests must be carried out timely,such as rice blast,sheath blight,false smut,rice skipper butterfly,snout moth’s larva,rice planthopper and rice thrips,etc.,especially in the middle and late growth periods of rice,the prevention of sheath blight,snout moth’s larva of the second generation and rice planthopper was particularly important.

High-yield Culture Technique of Ratooning Rice

Timely applying enough N fertilizer for bud development

Timely applying enough N fertilizer for bud development,timely supplementing the nutrients for stems and sheaths of middle-season rice,keeping the vitality of latent axillary buds to promote its germination,and providing the nutrients for stirring buds to prevent premature senility,was one of the key technical aspects realizing high and stable yields of ratooning rice.Generally,for the rice field with moderate fertilizer and normal production of middle-season rice,a single basal application of 225 -255 kg/hm2urea should be conducted 3-7 d after full heading of middle-season rice; for the rice field with good growth vigour,less urea should be applied; for the rice field with poor fertility,more urea should be applied,namely 300 kg/hm2urea should be broadcasted 10 d after full heading.

Harvesting middle-season rice according to buds

Too early harvesting of middleseason rice would not only cause the decrease of 1 000-seed weight,influencing quality and yield,but also break the nutrition supply because of less mature of grains and incomplete transfer of nutrient center,thereby causing slow emergence and even death of axillary buds,so that the sprouting amount would be reduced.Too late harvesting of middle-season rice would cause shattering seriously when harvesting,and also increase the risk of ceaseless autumn rain at the heading of rationing rice.The best harvesting time in Luxian was about August 10,then axillary buds of the second and the third node orders from the root had already extended 2-3 cm.During the harvesting of middle-season rice,the damage to rice stubble should be reduced to the least extent;after the harvesting,rice stubble recovery should be supported timely.2-3 d after the harvesting of middle-season rice,75 kg/hm2urea should be applied once for promoting seedlings.Therefore,water management of the field must be strengthened,and drought-resisting,bud- and seedlingprotecting work must be done well.

Keeping high stubble height

For fast cooling in autumn and short period for the growth of ratooning rice,so fully using early and fast emergence of axillary buds of first rice stubble and ear bearing of axillary buds of the second and the third node orders from the root was another key technical aspects realizing high and stable yields of ratooning rice.To preserve axillary buds of the second and the third node orders from the root,the stubble height when harvesting was 35-40 cm.

Preventing plant diseases and insect pests

During the retention stage of ratooning rice,main plant diseases and insect pests were snout moth’s larva of the third generation,rice planthopper and rice case worm,etc.,so pricking therapy should be used,meantime,high effect,low poison and low remnant pesticide and biopesticide should be chosen as far as possible,thereby ensuring the yield and quality of ratooning rice.

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