Everything you need to learn about the cultivation, harvest and storage of perennial crops!
Contents:
- How to Cultivate and Harvest Globe Artichoke?
- How to Cultivate and Harvest Jerusalem Artichoke?
- How to Cultivate and Harvest Rhubarb?
- How to Cultivate and Harvest Horseradish?
A variety of crops with mouth-watering delicacy come under the group perennials. They can be commercially cultivated in temperate to sub-tropical climates of India. These crops are of much significance in the world market and their cultivation in areas bestowed with ideal soil and climatic conditions will boost the economic condition of the farming community.
Since these crops occupy the land for a number of years, care should be taken in initial establishment of the farm. Soil should be thoroughly prepared and adequate quantity of organic manure should be incorporated at the time of preparation and should be supported with organics every year. Sufficient spacing should be provided, drainage ensured and best quality planting materials must be used.
Once established, perennial vegetables are easily manageable with a special care during extremes of weather and with regular agronomic practices.
1. How to Cultivate and Harvest Globe Artichoke?
The true artichoke, a member of the thistle family, is known to the trade as the Globe Artichoke. Globe artichokes are perennial, frost sensitive, thistle-like plants with edible flower buds. The flower buds arise on the terminal portion of the main stem and on lateral stems. Several pointed, leathery green bracts fold around a purple-blue flower. The edible bud is made up of a cone of short, thick-stemmed bracts.
The base of each bract is the fleshy edible portion, along with the fleshy center of the artichoke on which the flower and bracts are borne. In addition to minerals and vitamins, artichokes contain about 3% protein and 0.2% fat. Buds that are left on the plant open to 15 cm purple-blue flowers. These are dried and used in floral arrangements.
Artichokes do best in a frost-free coastal area with cool foggy summers. Under such conditions the plant receives the proper vernalization and the right climatic conditions throughout its growing period to produce compact, tender buds for an extended period. They do not over winter in areas with deep ground freezes. Brief periods of exposure to temperatures past below freezing cause no apparent damage. Care must be taken that artichokes are not exposed to temperatures below -5°C in the winter.
Where this occurs, straw mulching is recommended. It is advisable to chop off the stalks in the fall after the last harvest and to lay mulch before the first frost occurs if the field is to be maintained over winter. At temperatures below -10°C severe losses of crowns would be expected even with mulch protection. A hot dry climate causes artichoke buds to open quickly and destroys the tenderness of the edible parts.
After a few days the blistered skin turns dark; this does not impair the eating quality of the artichoke but make it more difficult to market. The globe artichoke will grow on a wide range of soils, but it produces best on a deep, fertile, well-drained soil. The plant is deep rooted and should be planted on soils that provide adequate area for root development. A pH range of 6.0-7.5 is the most ideal.
Cultivation:
Production from seed is best when transplants are grown and set out early enough in the spring to satisfy vernalization requirements. Transplants might also be properly vernalized by holding them under refrigeration for the needed time. Direct seeding may be possible if seed vernalization is effective. The normal method of propagating artichoke is from crown divisions or side shoots ensuring true to type plants in the field.
Care must be exercised in obtaining clean planting stock as a number of diseases are easily transmitted in this manner especially Curly Dwarf and some crown and bud decay organisms. Proper rotations, field selection, sanitation, spacing, fertilizer and irrigation practices can reduce the risk of many diseases. Planting is done in furrows at a spacing of 75 × 60 cm or 100 × 60 cm.
Moisture stress may cause a physiological disorder called Black Tip. This disorder usually damages only the exposed bracts of small axillary buds. The tip of the affected bracts become dark brown or almost black, dry, and leathery. The edible portion of the bud is not affected but the bud is rendered unmarketable. Damaged tissue may become a site for post-harvest decay. Careful attention to soil-water relationships is important in alleviating this disorder. Lighter soils need more frequent, but less water per application.
Gibberellic acid (GA3 or GA 4+7) foliar applications can enhance earliness by several weeks and improve uniformity of flowering. Application (30ppm) is usually made 5-7 weeks after transplanting, when plants are 45-60 cm in diameter. Damage may occur when applications are made too early, at high rates, and when excessive temperatures occur during or immediately following application.
Artichoke plants grown from seed tend to be variable with only 60-70 percent of the plants producing marketable “chokes.” A hybrid namely Imperial Star does not need as much vernalization as Green Globe. It is thorn less, and is primarily green, but has some purple tinting. It is reported to be tolerant to warm summer temperatures. Purple Sicilian is a purple globe artichoke, more tolerant to heat and cold and grown from seed. Northern Star is reported to be hardy to temperatures below 0°C without winter protection.
An artichoke is ready for harvest when it has reached maximum size, but before the bracts open. Cut the top one first (King Head), then the secondary ones as they mature. Harvest by cutting the stem 2 to 4 cm below the base of the bud. Old stems should be removed as soon as all buds have been harvested, to allow the new stems to grow.
Storage:
The edible bud is seldom stored; but even for a temporary holding a temperature of 0°C is recommended, with a relative humidity of 90 to 95 %, to prevent wilting or drying. To maintain quality and storage life, the buds should be pre-cooled to below 5°C on the day of harvest. Artichokes of good quality without decay or freezing injury will keep in good condition for 3 to 4 weeks at 0° C.
If fields are to be maintained over winter, chop and bury the above ground plant residue after harvest and after the leaves become dormant in late fall. Burying the residue is important in reducing carryover of pathogens and insect pests. Where ever appropriate, cover the rows with clean straw or clear plastic and improve the over-winter survival. The plastic or straw has to be removed when growth begins in spring.
2. How to Cultivate and Harvest Jerusalem Artichoke?
The Jerusalem artichoke is a tuberous rooted perennial. Various American Indians grew it for centuries as a staple food. They referred to it as girasol, while the French prefer to call it top in ambour. The plant is also known as “sunchoke” since its small yellow flowers resembles those of its close relative; the sunflower. Interest in Jerusalem artichokes extends beyond the use of this crop for food purposes.
The primary interest, since the early 1900s, has centered on the use of this crop for alcohol production as a fuel or fuel additive and as a source of raw product for fructose sugar. Jerusalem artichoke has been also used as a livestock feed and a forage crop. The mature tubers resemble knobby, new Irish potatoes in appearance. Although a perennial crop by nature, it is grown as an annual.
Propagation is very similar to that for Irish potatoes, and the tubers are used similarly.
Mammoth French White, Stampede, Brazilian White, Brazilian Red. ‘Fuseau’ (long 1-inch diameter tubers), ‘Smooth Garnet’ (red-skinned), and ‘Golden Nugget’ (good slicing type).
Plant, as early as possible in the spring. Late planting result in low yield and small tubers. Use about 500 kg seed pieces that are 50 g each. Spacing should be 30-60 cm apart with 125 cm between rows. Rhizomes should be planted 8-10 cm deep in fairly well drained soil. Deeper or shallower planting will result in slightly lower yield. Deeper planting result in a crop that is more difficult to harvest.
Yield of Jerusalem artichoke depends on plant population, length of season and management of the crop. When tops are left on to maturity yield of tubers averages 29 tons/acre. When tops are removed for silage prior to root maturity, fresh weight yield of tops averages 5 to 27 tons/acre and tuber weight ranges from 3 to 27 tons/acre depending on date of top removal, year and row spacing. The large, woody foliage has to be cut and removed before harvest.
Storage:
Jerusalem artichoke tubers can be stored at 0°C and 90-95 % relative humidity for 4-5 months. At low humidity they shrivel badly.
3. How to Cultivate and Harvest Rhubarb?
Rhubarb originates from Siberia; and is a very hardy perennial plant that forms large fleshy rhizomes and large leaves. The thick succulent leafstalks (petioles) having attractive red color are the edible parts.
It does not thrive where the summer mean temperature is much above 25°C and the winter mean is much above 5°C. It is frost resistant; in fact it needs a period of frost in the winter to produce the best stalks. It is best to grow rhubarb in full sun, but is fairly tolerant of partial shade. A well-drained but moisture-holding soil with a pH of 6.0 to 6.8 is ideal. The lighter soils will produce an earlier crop but require more irrigation and fertilization.
Soil Preparation and Planting:
Rhubarb grows best in a neutral soil which has been dug to a depth of 60 cm or more. Incorporate as much organic matter as possible during the digging because it must last the life of the plant. Once established Rhubarb will not tolerate soil disturbance. Rhubarb can be grown either from seed or from plants (crowns). The problem with rhubarb grown from seed is that it takes a year longer to produce stalks and even then, the plants are not guaranteed to be true to type and show a great deal of variation in color and form.
Healthy, vigorous 3 to 4-year old plants can be lifted and split into three or more ‘crowns’. The crown pieces are planted such that the top of the plant is 2.5 cm below the soil surface, 60-90 cm apart, in rows about 120-180 cm apart. Fill in around the plant with soil, gently firming it down to ensure that no air pockets remain.
Water well if the conditions are dry. Spread mulch (garden compost or other well-rotted organic material) around the plants, but not directly above where the crown will emerge in a month or so. About 3600 plants would be needed per acre. Rhubarb intended for mechanical harvest is planted 45 cm apart in rows 120 cm apart (at much higher in-row populations than fields for hand harvest). This spacing would require about 7200 plants per acre.
Rhubarb requires very little care, but if cared, they will produce much finer stalks than neglected plants. Every year after the leaves have died down, spread a new layer of garden compost or other well-rotten organic material around. This will conserve water and prevent weeds. Irrigate during dry periods. The only other attention required is to cut off flower heads which may appear in early spring as the new rhubarb stalks emerge. Do it as early as possible – if the flower head is left to grow and set the seed, the plant will never fully recover to good strength.
Rhubarb varieties are classified as red or green. Green types are again differentiated as green and speckled (pink).Only the red varieties are important.
Red Types:
The variety Crimson produces brightly colored red stalks with the unique characteristic of being red throughout under normal temperature and moisture conditions. Other popular red varieties are Canada Red, Ruby, Valentine and Cherry Red producing long, thick, deep-red stalks.
Speckled Types (Pink):
Victoria is an old variety that produces large stalks of excellent quality, long, round with smooth ribs; but poorly colored. It develops pink speckling on a light green stalk with the pink color being more intense at the bottom of the stalk, fading to a solid green near the top. Victoria is commonly used for forcing. Strawberry and MacDonald are other “pink” types that yield well. German Wine is similar to Victoria but slightly more vigorous and more intense in color, typically with a darker pink speckling on a green stem.
Green Types:
Riverside Giant is a cold-hardy, vigorous producer with large diameter, long and green stalks. Burgess Colossal is large but produces pale green stalks.
Rhubarb requires a period below 5°C to break dormancy and stimulate the production of leaf petioles. When temperature begins to exceed 5-10°C, crown buds begin to develop. At the end of petiole harvest new shoots will emerge. These will provide the reserves for the following year’s crop. If growth and moisture reserves are adequate, a second harvest can be made but stalks must be firm and not pithy.
Rhubarb crowns may be harvested for “forcing” indoors to obtain stalks for market earlier than would be possible from the field. This involves the digging of entire crowns and selecting the largest to place in a “forcing house” at a later date. Harvest of forcing rhubarb usually begins in early January. Usually two or three years old crowns are used for forcing. Large crowns with a few large buds are preferred. Crowns from fields that have been harvested for outdoor production are not recommended for forcing, due to the poorer yields that result.
Rhubarb crowns in the field must be allowed to go into dormancy and exposed to a certain rest period before any forcing is possible. This requires exposure to temperature between 0 and 10° C for 7 to 9 weeks at the end of the growing season. Exposure to temperature below 0°C reduces yield, while temperature above 10°C contribute nothing to the required rest period.
The amount of cold required, before forcing can be started, is referred to as “cold units.” Cold Units are the accumulated number of degrees below 10°C (and above 0°C) as recorded at mid-morning. Varieties such as Victoria and German Wine will require about 470-500 cold units to force successfully.
Crowns may be subjected to cold treatment for accumulation of the required cold units either in the field, or in the forcing structure. Gibberellic acid may be used to substitute for a possible lack of cold induction and to increase uniformity of growth. At the appropriate time, crowns are plowed out of the ground and placed on the earth floor of the forcing structure as close to each other as possible.
This requires about 1 square foot per crown. The space around each crown is filled with soil, leaving walkways where needed. At the time when forcing is desired, the soil is wetted and temperature is raised to 15°C. This temperature has been found to produce the best yield. Temperature between 10°C and 15°C produce more intense red color but slower growth. Temperature below 10° C may reduce yield, and those above 16°C result in pale stalk color, a faster growth rate, and also may result in lower yield, especially if exceeding 20°C.
Regardless of the temperature, stalk color becomes less intense as the crowns are exhausted. It is important to maintain good, but not excessive, soil moisture around the roots in the forcing structure. Production drops off dramatically when the soil becomes dry. Forcing rhubarb is usually picked about twice a week for about 4-6 weeks. Separate forcing structures may be sequenced, for starting forcing at different times, to provide forced rhubarb till field rhubarb becomes available.
Harvesting, Handling and Storage:
Yield of rhubarb depends on the number of pickings, and the age and condition of the field. Yield may range from 6 to 12 tons per acre for red varieties. Green varieties tend to yield more. A well-maintained field may remain productive for 15 or more years.
Usually Rhubarb is hand harvested. For processing, both ends of the petiole are trimmed so that no leaf tissue remains. For fresh market a small amount (0.5 cm) of leaf tissue is usually left attached to the petiole and the basal end is not trimmed. Splitting of the petiole will be more serious if the entire leaf is removed. The leaves must not be eaten since they contain oxalic acid and are poisonous.
Stalks should not be pulled during the first year of growth. Stalk color is best after the field is 2 to 3 years old. Plants should not be over-pulled at any time, as a certain amount of foliage is required for the development of the present crop as well as next year’s crop.
Store at 0°C and 95 to 100% Relative Humidity. Rhubarb can be hydro- cooled or air-cooled, and the temperature of the stalks should reach 0°C within 1 day of harvest. The topped bunches or loose stalks should be packed in crates, and the crates should be stacked to allow ample air circulation; otherwise, there is danger of heating and mold growth. Moisture loss in storage will be much less if the bunched or loose stalks are packed in crates lined with perforated polyethylene film.
4. How to Cultivate and Harvest Horseradish?
A hardy perennial usually grown as an annual for the pungent roots. These roots contain oil that gives the roots a hot biting pungent taste. This sharp taste makes it valuable as a condiment.
Horseradish is divided into two general types, “Common” and “Bohemian”. “Common” types have broad crinkled leaves and are considered to have superior quality, while “Bohemian” types have narrow smooth leaves, somewhat lower “quality, but better disease resistance.
Use planting stock from root cuttings (called set’s) that have been trimmed from the crop’s main roots at harvest. Use root pieces with a diameter of 1.0 to 1.5 cm and 20-30 cm long. Space rows 90-120 cm apart, with in- row spacing of 25-40 cm. About 8700-9700 root cuttings will be required per acre.
Give a slanting cut on the lower end and a square cut at the top in order to have a proper root placement in the soil. Plant roots as early in the spring as ground can be prepared. Place the root at an angle of about 45° in the soil for vigorous establishment and growth. About a year is required to produce a crop. Since fields may be harvested in fall or spring, the spring harvest usually provides planting stock. Under conditions where planting stock is available, and roots have time to get established, fall planting is also feasible.
Greater yield will be obtained if horseradish is irrigated during dry periods. The benefits of irrigation will be greater on lighter soils where crops are more subjected to moisture stress. Lighter soils need more frequent water applications, but less water applied per application.
Harvesting, Handling and Storage:
Approximate yield ranges from 7.5 to 10.0 t/ha. Horseradish makes its greatest growth in late summer and early fall. Harvest is usually delayed till October or early November for best yield. Fields can be harvested in fall or spring.
Harvesting is usually not started until a frost has killed off the tops. If harvesting is done before that, tops should be removed as close to the soil surface as possible. Allow several days between leaf removal and harvest. Before the roots are sent to the processor, small roots must be removed as the planting stock for the next season. Store the roots and planting stock at low temperatures and high humidity with good air circulation.
Horseradish can be stored satisfactorily up to 10-12 months at -1 to 0°C and 90-95% relative humidity. Perforated plastic bags or bin liners can aid in maintaining the high humidity. Roots should be kept in the dark because they can become green when exposed to light.
Roots dug when the plant is actively growing do not keep as well as, those conditioned by cold weather before they are dug. Frequent inspection in storage is advisable. Horseradish can also be stored over winter in cool cellars or in outdoor pits or trenches.
The requirements for marketing the roots are- A well-flavored root, reasonably straight, without side shoots, and no mechanical or decay damage. The roots should be at least 20 cm long with a diameter of not less than 2 cm.
Horseradish is commonly packaged in 30 kg sacks, 25 kg sacks, 2.5 kg cello packages, or delivered in bulk for processing.