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| Planting date. Date of planting varies according to the location and year to year variation in the traffic ability of the soil and estimated soil water supplies. Typical planting times and seeding rates are summarized in Table 4. When established very early, plants are more susceptible to frost and pathogens. Early plantings also result in taller plants than later ones. Excessive vegetative growth may exhaust stored soil water before seed matures. Best results on Sacramento Valley rice lands are derived from fields planted before May 1. In the southern San Joaquin Valley, planting may take place from January through mid-March, and in the Imperial Valley in January and early February. In other areas and in years with low soil moisture, late March and early April are usually the best planting times. By March, dryland producers will know better what moisture will be available for their crop. Later spring seedings under these conditions will result in smaller plants (1.5 to 2 feet high), with sufficient moisture remaining for grain filling. |
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| Late plantings. Safflower is often planted in the Yolo Bypass area near the city of Sacramento and other seasonally flooded areas in very late spring (mid-May to June) when soils dry sufficiently for cultivation. Other growers plant safflower late on occasion because of crop failure or a lack of other alternatives. Safflower will grow when planted at such times, but blossoming is delayed until late July or early August. Yields vary under these conditions from 800 to 2,000 lb/acre, but commonly are reduced by 50 % or more compared to optimum planting times at the same location. Also, the risk of early fall rains catching an unharvested crop are greater. Mature safflower seeds will sprout if they receive sufficient moisture, making them worthless. |
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| Seedbed preparation. Specific seedbed preparation practices vary in different areas of the state, with the previous crop, and with soil type. The type of seedbed prepared for pre-irrigated, drilled small grain crops usually works well for safflower. Soil moisture should be conserved near the surface while preparing the seedbed. Clay soils require special care. After the winter rains it may not be possible to work such soils until late spring, when cultivation and winds can dry out the seedbed to the depth of tillage. It is then necessary to use seeding equipment with special openers to push aside the dry soil and plant the seed down into moisture. On loam or clay-loam soils, with plantings made during the winter, heavy rains followed by dry winds can cause crusts to form, which have occasionally reduced emergence. When crusts develop, harrowing or ring rolling such fields after planting but before emergence has been beneficial. |
| Raised beds can reduce root-rot problems. Bedding practices vary depending on the equipment available and grower experience. In the Sacramento Valley, the 60-inch beds (150 cm) commonly used for tomatoes increasingly are preferred for safflower as well. In the San Joaquin Valley, beds used for cotton and sugar beets (30 or 40 inch rows; 76 to 102 cm) have been successful. Other planting arrangements however are successful at times as well. |
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| Fertilizer rates and application. A number of factors influence fertilizer recommendations for safflower. These include yield expectations, available soil moisture, previous cropping and fertilization practices, and planting date. Frequently N is applied in amounts ranging from 75 to 175 lb/acre (84 to 196 kg/ha) for irrigated safflower, and about 30 to 60 pounds (34 to 67 kg/ha) for dry-farmed safflower grown on shallow, upland soils in the coastal foothills. In a series of trials in the Sacramento Valley, maximum yields were achieved by fertilizer applications of 100 to 150 lb/acre (figure 7). In several other trials, some with low and some with high yields, there was essentially no response to fertilizer. Soils either were high in fertility, or some other soil limitation, likely associated with soil moisture, reduced crop response. In an experiment carried out with increasing levels of irrigation water, yields failed to increase significantly above 120 pounds of N per acre, though there was a tendency for increasing numbers of tertiary buds to set seed at higher rates (figure 4) |
| If more than 1.5 tons per acre (3,375 kg/ha) of straw or dry crop residue per acre is returned to the soil by the preceding crop, the larger amounts indicated should be applied both to help decompose the crop residues while providing sufficient nutrients to fertilize the safflower crop. Fertilizer rates applied to safflower following a legume, such as alfalfa, or a heavily fertilized vegetable crop such as tomatoes, should be adjusted for residual soil N. Yields may be reduced by an excessive N supply leading to exhaustion of soil moisture by vegetative safflower. Similarly, yields of dry-farmed safflower, even in fallow systems, will be reduced if the fertilization rate produces excessive vegetative growth that exhausts soil moisture prior to seed maturation. |
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| Figure 7. Relative yield and nitrogen fertilizer rates from a number of trials in the Sacramento Valley. Data are summarized from trials conducted in the 1960s. Maximum yields ranged from 1500 to greater than 3000 lb/acre (1680 to 3360 kg/ha), similar to current yield levels achieved in the same locations. Relative yield = 61.5 + 0.42 N (lb/a) - 1.1 N2 (lb/a) (R2=0.83). Source: Adapted from Werkhoven, et al., 1968; Kearney 1997. |
| When planted following rice, P deficiency can develop in safflower. With March or April plantings, the seedlings turn yellow, develop a leaf tip burn and may fail to grow normally (plate 2). This symptom is due to reduced soil phosphorus availability. Phosphorus is less available to rotational crops on soils that have been flooded (anaerobic) for long periods and additional P fertilizer may be required. When phosphorus is needed, 40 to 60 lb/acre of P2O5 (17 to 26 lb/acre of elemental P; 19 to 34 kg/ha) typically are applied. Because P is not very mobile in most soils, fertilizer should be placed near the seed. Safflower following long-term rice production may not yield as well as it would following other crops requiring well-aerated soils, even if P fertilizer were applied. |
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| Plate 2. Phosphorus-deficient safflower seedlings. |
| Safflower recovers a large amount of potassium (K) and has responded occasionally to K application. Significant yield increases were obtained by supplying K to mineral soils with perched water tables in the Delta region when soil test results2 indicated very low K levels. In such cases, 75 to 90 lb/acre (84 to 100 kg/ha) of K2O have been sufficient. Apart from N, P, and K, no deficiency of other plant nutrients has been found to limit safflower production in California. |
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| Seed treatments. Safflower seed typically is treated with a fungicide to reduce the occurrence of seedling rust. Rust spores can contaminate warehouses and seed cleaning equipment. Some safflower is grown organically or simply without pesticides, including fungicides, to meet special marketing niches. Seeds for these programs may not be allowed to be treated. Growers should determine the current restrictions on seed treatment for organic or other specialty marketing programs. |
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| Seeding rates. Matching a safflower stand to the moisture available to the crop is the key to successful production. Since light interception always limits crop yield, the objective in safflower stand establishment is to secure a complete leaf canopy as soon as possible in the growing season, without exhausting soil moisture reserves before the end of the seed maturation period in the process. Seeding rates depend on the moisture available to the crop during the growing season, the time of seeding, row spacing, seed size, and seeding method. Typical seeding rates are given in Table 4. Some additional factors must be considered, however, when deciding about rates. On shallower, upland soils, where dry farming is practiced, seeding rates should be lower than under other conditions, since available soil moisture likely will be limiting. When soil moisture is thought to be limiting, a closed crop canopy may not be desirable. Close rows planted with a grain drill require higher rates than row planters. Broadcast seeding requires more seed (approximately 10 lb/acre; 11 kg/ha) to compensate for loss of seed during the covering operation (harrowing) when some seed will be buried too deeply and some not deeply enough. For late plantings where it is necessary to plant deeper to reach moist soil, seeding rates should be increased by 5 lb/acre (6 kg/ha) to compensate for lower emergence. |
| Plant populations for a satisfactory stand. Safflower yields do not vary over a wide range of seeding rates, provided sufficient soil moisture is available to supply a complete crop leaf canopy with moisture through the grain-filling period. Growers should seek to have a complete crop canopy no later than first bloom, and preferably by flower bud formation. |
| For seedings using a grain drill, rows may be 6 to 12 inches (15 to 30 cm) apart. In row plantings the rows should be 18 to 30 inches apart if the crop is grown on dry land. Under irrigation, rows should not be more than 30 inches apart. Safflower in rows 20 to 30 inches (50 to 76 cm) apart (either irrigated or dry-farmed) should average five to 12 plants per linear foot of row (16 to 39 plants per m). Late-sown stands will produce smaller plants with fewer heads. This requires narrower rows to achieve complete row cover. For example, growers using 60-inch beds (1.5 m) plant two rows early in the season, but should plant three late in the season. |
| For solid stands planted with a grain drill in upland, dry farming systems, three to five plants per square foot are adequate. On irrigated or high water table land up to five to ten plants per square foot are desirable. Stands of less than two plants per square foot usually result in excess weed competition, especially if herbicides are not used. Under dry-farmed conditions, if the stand exceeds six plants per square foot, overcrowding, especially in years with moisture limitations, may reduce yields. |
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| Seeding methods. Different types of planters are used successfully with safflower. Hoe-opener drills are used frequently for both solid and row plantings (by stopping an appropriate number of seed feeds or runs). Row crop planters are used on raised beds. For plantings in rows of 20 to 30 inches (50 to 76 cm), most of the conventional-type row planters can be adapted for safflower. |
| It is important to place seed in moist soil. Late spring plantings, when the surface soil is drying out very rapidly, should be made only with a corn shoe-opener drill to insure seed placement into moist soil. Preferably the seed should not be planted into the moisture deeper than 2 to 2.5 inches (5 to 6.5 cm), although the seedlings will emerge from a depth of 3.5 inches (9 cm) if a surface crust does not develop. If seed is broadcast, harrowing should cover seed to a depth of 2 to 3.5 inches. |
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| 1N fertilizer rates must be related to yield expectations. In the Sacramento Valley, sufficient rainfall may occur to allow for minimal irrigation of safflower. If soils are deep and reasonable yield expectations are 2,000 to 3,000 pounds of seed per acre, then fertilization should be similar to irrigated safflower in the same region. |
| 2Ammonium acetate test. |
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Irrigation [9] |
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Modified: 11 Jun 1999
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