High-yield and High-efficiency Standardized Cultivation Technique for Wheat Interplanting with Peanuts

*

1. Shandong Peanut Research Institute, Qingdao 266100, China; 2. Weifang Food and Drug Inspection and Testing Center, Weifang 261100, China; 3. Wendeng District Agricultural Technology Extension Station of Weihai City, Weihai 264404, China; 4. Yantai Academy of Agricultural Sciences, Yantai 265500, China

Abstract Through wheat interplanting with peanuts, it is able to make full use of the light and heat resources in the growing season to achieve high yield of both wheat and peanuts in two seasons of one year. Wheat interplanting with peanuts is one of the main cultivation methods of wheat and oil crop double cropping system, and has very broad development prospects in the Huang-Huai-Hai region. This paper summarized high-yield the high-efficiency and standardized cultivation techniques for wheat interplanting with peanuts, including crop rotation, proper deep ploughing, balanced fertilization, rational matching of fine varieties, interplanting at suitable time, sowing according to certain specification, and enhancing the field management. This can be used as reference for high-yield and high-efficiency standardized cultivation technique for wheat interplanting with peanuts.

Key words Peanut, Wheat interplanting, High yield cultivation

1 Introduction

With the continuous decrease of cultivated land area, the contradiction between grain and oil crops in the Huang-Huai-Hai region has become increasingly prominent. Developing the double cropping system and increasing the utilization rate of unit land are effective ways to alleviate this contradiction[1]. Through wheat interplanting with peanuts, it is able to make full use of the light and heat resources in the growing season to achieve high yield of both wheat and peanuts in two seasons of one year. It is one of the main cultivation methods of wheat and oil crop double cropping system. In recent years, Shandong Province has made greater research efforts on key factors influencing he continuous improvement of production of wheat interplanting with peanuts, and has made important progress in high-efficiency fertilization and rational population formation. It has realized the yield of peanuts up to 7 500 kg/ha, and the yield in large field realized 6 750 kg/ha, established a high-yield and high-efficiency cultivation technique system for wheat interplanting with peanuts. The technique mainly includes following points.

2 Crop rotation and proper deep ploughing

Both the experiment and production have proved that similar to the spring peanuts, if continuous planting double cropping system of wheat interplanting with peanuts can also cause aggravation of peanut pests, poor plant development and yield decline. Therefore, double cropping system of wheat interplanting with peanuts should implement 2-3 years of crop rotation with double cropping variety combinations such as wheat-maize, and wheat-cotton. In terms of the soil, it is preferably sandy soil or loam. The clay with poor permeability or the sandy soil with poor ability to retain fertilizer can be improved by returning straw to the field[3]or adding organic fertilizer. Besides, the terrain should be flat and there should have convenient irrigation and drainage facilities. Deep ploughing can improve soil physical and chemical properties, increase the thickness of cultivated layer, and improve the effectiveness of mineral elements. Experiments have demonstrated that deep ploughing can significantly improve the effectiveness of elements such as iron and magnesium compared with no-tillage[4-5]. In addition, deep ploughing is also favorable for peanut root growth and plant development as well as yield formation, and increase of peanut pod yield. For the wheat interplanting with peanuts, the deep ploughing should be carried out before wheat sowing, and the thickness is preferably 30-35 cm.

3 Balanced fertilization

For the wheat interplanting with peanuts, the fertilization principle should take soil to determine the yield, and take yield to determine the fertilizer, add the organic fertilizer, reduce nitrogen and phosphorus fertilizer, and supplement the trace elements such as calcium[6]. In the land with medium or higher fertility soil and yield of 4.5 t/ha, it is recommended to apply 11.5-13.5 t/ha of barnyard manure, or 5.5-7.0 t/ha of decomposed chicken manure, or 1 350-2 250 kg/ha of commercial organic fertilizer, 210-270 kg/ha of chemical fertilizer ternary compound fertilizer, 100-130 kg/ha of slow release urea, 135-155 kg/ha of potassium sulfate, or 65-85 kg/ha of diammonium phosphate, 140-180 kg/ha of urea, and 200-235 kg/ha of potassium sulfate. For the land with yield of 6.0 t/ha, it is recommended to apply 15.0-18.0 t/ha of barnyard manure, or 7.5-9.0 t/ha of decomposed chicken manure, or 1 800-3 000 kg/ha of commercial organic fertilizer, 280-360 kg/ha of chemical fertilizer ternary compound fertilizer, 130-170 kg/ha of slow release urea, 180-205 kg/ha of potassium sulfate, or 65-85 kg/ha of diammonium phosphate, 190-245 kg/ha of slow release urea, and 265-310 kg/ha of potassium sulfate. For the land with yield of 7.5 t/ha, it is recommended to apply 19.0-22.5 t/ha of barnyard manure, or 9.0-11.5 t/ha of decomposed chicken manure, or 2 250-3 750 kg/ha of commercial organic fertilizer; 350-450 kg/ha of chemical fertilizer ternary compound fertilizer, 165-210 kg/ha of slow release urea, 225-255 kg/ha of potassium sulfate, or 110-140 kg/ha of diammonium phosphate, 235-305 kg/ha of slow release urea, and 330-390 kg/ha of potassium sulfate. Peanut-specific fertilizers with equivalent nutrient content, or other compound fertilizers, also can be applied. For some regions, especially those land parcels where peanut growth and development are poor or pods are vulnerable to become empty, it is possible to apply calcium fertilizer or trace element fertilizers every two years. For calcium neutral or acidic soil, it is recommended to apply lime (450-750 kg/ha), lime nitrogen (375-450 kg/ha), silicon calcium fertilizer (450-600 kg/ha) calcium magnesium phosphate (250-300 kg/ha),etc.; for alkaline soil or saline-alkali soil, it is recommended to apply plaster (450-600 kg/ha). The trace element fertilizer mainly includes borax or boric acid (7.5 kg/ha), ammonium molybdate (7.5 kg/ha) and zinc sulfate (7.5-15 kg/ha). For the land planted with peanut in previous season, organic fertilizer and trace element fertilizer should be applied together with wheat base fertilizer before deep ploughing in the autumn. Nitrogen, phosphorus, potassium and calcium fertilizers should be applied after the harvesting of wheat and before flowering of peanuts.

4 Making well preparation of fine varieties

4.1 Taking into consideration both the previous and subsequent crops, and rationally matching fine varietiesIn interplanting areas, wheat varieties should select those varieties with compact plant types, short or moderate plant height, disease resistant, lodging resistant, early or medium maturing varieties, and it is also necessary to make effort to reduce the light shading influence of wheat on peanuts. Peanut varieties should select large medium and early maturing varieties with high potential of yield increase, good stability of yield; besides, the varieties should have high disease resistance, and high utilization rate of nitrogen, phosphorus, and potassium[7-9], have no obvious defect, and have been approved and certified by the national and provincial authorities. Such varieties include Huayu 22, Huayu 25, Huayu 33, Huayu 36, Shanhua 7, Shanhua 9, Weihua 11, Weihua 10, and Linhua 5.

4.2 Proper seed treatment before sowingIn order to reduce the number of bacteria of seeds and increase the vigor of the seeds, the pods should be sun dried before peeling, usually 2-3 d. After peeling, the peanut seeds were divided into three grades, and the first and second grades with plump seeds, bright color and intact appearance were selected for sowing. In order to prevent damage of underground insects and pests, pesticides or bactericide may be used for seed dressing before sowing.

5 Interplanting at suitable time and sowing according to certain specification

The peanut interplanting period mainly depends on the size of wheat canopy and the row spacing of wheat. For the high-yield wheat field with severe shading, the suitable interplanting time is 10-15 d before harvesting of the wheat, for the low and medium yield wheat field, the suitable interplanting time is 15-20 d before harvesting of the wheat.

The row spacing of peanut interplanting depends mainly on the row spacing of wheat. If the condition permits, it is recommended to adopt 30 cm equal row spacing of wheat. Such sowing method is favorable for the development of wheat population and yield formation, and is also favorable for the peanut interplanting and growth of symbiotic peanut seedlings. If the condition is not suitable for equal row spacing, the row spacing of peanut should be kept within the range of 30-35 cm, and should not exceed 40 cm. Regardless of the wide or narrow row spacing, the suitable sowing density of peanuts is 143 000-158 000 holes/ha, 2 peanuts per hole, and the number of harvested plants is not less than 263 000 plants/ha. Alternatively, it is feasible to adopt single seed fine sowing, the suitable sowing density is 203 000-218 000 holes/ha[10-11], and the number of harvested plants is not less than 188 000 plants/ha. For varieties with high soil fertility or varieties with long growth period and many branches, the sowing density may be appropriately reduced, and vice versa.

At the time of interplanting, herringbone frame can be made using bamboo pole, a person is responsible for separating wheat plants in the front, and others open ditches (holes) to sow peanut seeds according to the specified density. The sowing depth should be about 3 cm, the hole spacing should be uniform. After sowing, it is required to cover the seeds with soil immediately. The peanut interplanting drill may be used. In addition, it is required to pay attention to the sowing depth. The sowing depth should be uniform. Too deep or too shallow depth will influence the uniform, complete, and robust characteristics of peanut seedlings. If the soil moisture is not adequate, it is recommended to irrigate in combination with the wheat grain-filling stage at 5-7 d before the interplanting. Also it is feasible to first sow then irrigate. The key point is suitable soil moisture.

6 Field management measures through combining the promotion and control

6.1 Early stage management (sowing to flowering)At this stage, the management should focus on ensuring complete and strong peanut seedlings. (i) Watering in time. In the emergence process of peanut seedlings, due to high temperature and high water consumption of wheat, peanut seeds are vulnerable to dryness due to lack of water in the soil. Therefore, before harvesting of the wheat, the soil moisture in the wheat field should be observed at any time. In case of drought found, it is required to irrigate along with the wheat ridges, to make sure that the peanuts sprout out on time and achieve a uniform seedling. (ii) Harvesting the wheat in proper time. The best harvesting stage of wheat is dough stage. At this stage, harvesting can obtain the highest yield and can promptly release the peanut seedlings. (iii) Tillage in proper time. The first tillage should be carried out within 5-7 d after the harvesting of the wheat. At this time, the main task is to remove previous crop and loosen the soil, remove the weeds in the field, and promote the normal growth of the seedlings as soon as possible, and shorten the seedling hardening period. The second tillage should be carried out before flowering. At this time, it is recommended to open 5-10 cm wide ditches beside the peanut seedlings, and apply the chemical fertilizers within the ditches, and cover with soil, then water.

6.2 Middle stage management (flowering to the late pod stage)At this stage, the management should focus on ensuring robust development of peanuts. (i) Prevention and treatment of diseases and insects in time. From the flowering, it is recommended to spray the leaf surface alternately with different fungicides, and spray 2-3 times at intervals of 10-15 d to prevent leaf diseases; in the hot and high humidity season, it is necessary to pay attention to the control ofHelicoverpaarmigera; if the undergroundHolotrichiadiomphaliaandPleonomuscanaliculatusare found at the pod bearing stage, it is recommended to spray pesticides such as phoxim. (ii) Weeding by chemical method. After the second tillage, it is recommended to seize the opportunity of adequate soil moisture, promptly spray 50% acetochlor EC, 1 500 mL with 750-900 kg of water, for ground spraying, the effective period is as long as one month or longer. If two times of spraying is performed, it is able to ensure no damage of weeds during the entire growth and development period of peanuts. During pesticide spraying, it is required to avoid the peanut plants as much as possible. (iii) Proper watering in the proper time. At the full bloom stage, in case of drought, it will exert a great influence on the peanut growth and the yield formation. When the plant leaves have symptom of wilting, the areas with well-established irrigation facilities should water promptly, to ensure normal flowering and increase the seed setting percentage. (iv) Earthing up and making preparation for pegs. When plants grow to the state of being close to ridge sealing, it is necessary to take the opportunity of adequate soil moisture to open ditches and earth up, to make the high position pegs penetrate into the soil, and increase the number of pods per plant. For earthing up, it is expected to realize clean ditch, soft soil, fat ridge waist, and concave ridge top. For land parcels with weeds, it is necessary to remove weeds first, and then earth up and prepare the ridges. (v) Prevention and control of the iron deficiency in time. In the hot and rainy season in July and August, peanuts are in the period of growth and development, so the nutrient demand for peanuts enters the peak period. In the event that yellow and white heart leaves appear on the top of the plants, it is recommended to spray 0.2%-0.3% aqueous solution of ferrous sulfate on the leaves in time at an interval of about one week. (vi) Chemical control at proper time. For peanuts interplanted with wheat, the internodes of the stems are poorly developed. Under high-yield conditions, peanut plants are prone to grow excessively and vulnerable to lodge. When the plant height reaches 30-35 cm, it is recommended to spray the plant growth inhibitors such as paclobutrazol or mepiquat chloride.

6.3 Later stage management (early pod filling stage to mature stage)At this stage, the management should focus on preventing premature of peanut plants. (i) It is recommended to prevent and control the rust and web blotch. (ii) Topdressing of foliar fertilizer. At about one month before harvesting, it is recommended to spray 1% urea + 0.3% to 0.4% potassium dihydrogen phosphate aqueous solution, spray 2-3 times at an interval of about one week. Besides, it is recommended to extend the functional period of leaves and roots, increase photosynthetic accumulation at late growth stage, and increase the full-seed pod rate. It is also feasible to spray multi-component foliar fertilizer that is rich in nitrogen, phosphorus and potassium. (iii) Watering or drainage in accordance with actual conditions. At the pod filling stage, the drought will accelerate the leaf falling speed, cause premature of the plants, affect the pod plumpness. Therefore, it is recommended to carry out timely watering, but the watering amount should not be too large. In the event of waterlogging, the plants are easy to become rotten, the plants will be mature later, so it is required to drain in time. (iv) Harvesting in proper time. Too early harvesting will influencing the plumpness of pods, reduce the yield and quality, while too late harvesting will also increase the percentage of rotten pods. According to the experience, the best harvesting period is the end of September to the beginning of October, and the harvesting should not impede the subsequent wheat sowing.