Harvesting immature farm products can lead to more loses than gains since these goods might not be appealing to the market. There are two types of maturity, the physiological maturity and the economical maturity. What is important if you are a seller of fresh produce is the economical maturity. The produce is economically mature if it has reached the stage when it appeals to the market. Physiological maturity is the stage of the plant it is capable of reproducing. An physiologically mature crop may be economically mature but not all economically mature produce are physiologically mature.
Below are maturity indices of some fruits, vegetables, root crops, oil crops and cut-flowers. I hope you will find them useful.
Fruits:

Durian

The fruit is a large (1.5 to 2.5 kg), spiny capsule that opens into five segments containing seeds covered with a pulpy, edible aril. External color changes with maturation from dull olive-green to light yellowish-green. When mature, the fruit drops to the ground, but it can be carefully harvested before this occurs and ripened in 4 to 6 days. Ease of fruit abscission can be used as a maturity index. Fruit is picked with peduncle attached.

Avocado

Percent of dry matter is highly correlated with oil content and is used as a maturity index in California and most other avocado production areas; minimum dry matter required ranges from 19 to 25%, depending on cultivar (19.0% for ‘Fuerte’, 20.8% for ‘Hass’, and 24.2% for ‘Gwen’).

Florida-grown avocado cultivars have lower oil content and are harvested on the basis of a calendar date (days after full bloom).

Caimito

Fruit are harvested when the flesh begins to turn red and mature when the newly exposed layer is turned from green to pinkish-brown, orange, or red. Immature fruit will fail to soften, and their pulp will turn dark-brown and inedible. Harvesting must be done carefully to avoid mechanical damage. Twist the fruit until it breaks from the stem. Poles with knifes at the end are also used to harvest fruit. Fruit should not be allowed to fall on the ground.

Vegetables:

Squash

Summer squashes (soft-rind) are consumed at a range of physiological maturities but are defined as immature fruits of the diverse Cucurbitaceae family. Depending on cultivar and temperature, the time from flowering to harvest may be 45 to 60 days for zucchini, yellow straightneck or crookneck, and scallop (Patty Pan-type) squash and 75 days or more for many of the Sponge squash (immature gourds) such as Luffa. Fruit may be harvested at a very immature stage, at the desired fruit size, before seeds begin to enlarge and harden. A thin, soft external rind and external glossiness are also indicators of a pre-maturity condition. The entire fruit is edible, either raw or cooked, without removal of seeds and seed cavity tissue. Small, young fruit are tender and generally have a slightly sweet taste.

Ampalaya

Desirable size reached but still tender (overmature if color dulls or changes and seeds are tough)

Sitao

Well-filled pods that snap readily

Okra

Desirable size reached and the tips of which can be snapped readily

Onion

Indicated when approximately 10 to 20 percent of tops have fallen over

· Conversion from active growth to dormancy accelerated by undercutting bulbs 1 to 2 inches

· “Field-dry” maturity is indicated when bulb neck is completely dry to the touch and not slippery. Typically reached at 5-8% weight loss following harvest.

Cutflower:

Rose

Roses are harvested at different levels of maturity, depending on marketing and cultivar. For long-distance transport or storage, roses should usually be harvested with some of the sepals reflexed. Flowers harvested before the sepals reflex may fail to open, or may be more susceptible to bent neck. Fast-opening roses, like some yellows and whites, should be harvested just before the sepals start to separate from the bud. The marketing life of roses harvested later will be reduced unless extra care is taken with their postharvest handling. Harvesting is most convenient using shears provided with auxiliary jaws to hold the bloom after harvest. The cut is normally made so as to leave 2 five-foliate leaves below the cut. When stem length is an important consideration, the cut may be made ‘below Roses should be purchased and sold by cultivar name. Avoid blooms that are already open – flowers should normally have some or all of their sepals (the green protective ‘leaves’ at the base of the flower) folded back, but the petals should not have started unfolding. Brown spots or patches on the outer petals may be an indication of Botrytis infection.

Orchids

Orchid flowers are usually harvested 3 to 4 days after opening, because flowers cut prematurely will fail to develop normally off the plant. Early and late in the season, individual flowers are cut from the spike as they develop, because prices are high at these times. In mid-season, the whole spike is cut. Virus diseases can be spread from plant to plant during harvest, so cutting tools should be sterilized before being used on the next plant or disposable razor blades should be used. As individual flowers, purchase when fully opens. Spikes should be purchased when at least two flowers per spike are open.

Carnation

The maturity at which carnations are harvested depends on the proposed marketing procedure. Star-stage buds are too immature for most purposes except long-term storage. Buds at the ‘paint-brush’ stage, with petals straight up, will open quickly. Flowers for immediate use are normally harvested with the outer petals between vertical and horizontal. To minimize spread of disease, avoid harvesting from plants with obvious disease symptoms. Many pickers place cut flowers on the top of wires for later collection into bunches. Flowers collected into canvas slings can be taken to the shed by mechanical devices ranging from overhead cables to tractor-hauled trailers designed to hold the slings. Standard carnations ship better and last longer if purchased in the bud stage while miniature carnations should be purchased when at least one flower per stem is open. Fragrant cultivars have more consumer appeal.

Oil Crops:

Sunflower

Sprouts, plant seedlings consumed shortly after germination, are produced from many vegetable and agronomic plant seeds. Harvest maturity is highly regulated by germination (sprouting) conditions. The desired sprout length is the primary maturity index and harvesting is done at a relatively fixed number of days following radicle (root) emergence. Depending on seed type, harvest generally occurs 3 to 8 days after germination (Ex. alfalfa and sunflower, respectively). Examples of typical desired sprout lengths are given below;

Coconut

Young coconuts are harvested 6 to 9 mo after flowering, as the nut approaches full size and the skin is still green (Consignado et al., 1976; Srivichai, 1997) and the short stem (rachillae) on the top of individual coconuts that originally held the male flowers (in Thai called ‘rat-tail’) becomes half green and brown. In immature nuts, the skin surface around the calyx (cap) on the top of coconuts is creamy-white or a whitish-yellow. When the area surrounding the cap is green the coconut is regarded as mature and is 10 to 12 mo old. At maturity the skin begins to change from green to yellow then brown and the ‘rat-tail’ is entirely brown.

Sugar Crops

Sugarcane

* Ripening and maturation phase in a twelve-month crop lasts for about three months starting from 270-360 days.
* Sugar synthesis and rapid accumulation of sugar takes place during this phase and vegetative growth is reduced.
* As ripening advances, simple sugars (monosaccharide viz., fructose and glucose) are converted into cane sugar (sucrose, a disaccharide).
* Cane ripening proceeds from bottom to the top and hence bottom portion contains more sugars than the top portions.
* Ample sunshine, clear skies cool nights and warm days (i.e., more diurnal variation in temperature) and dry weather are highly conducive for ripening.

Root and Tuber crops:

Carrots

* In practice, harvest decisions for carrots are based on several criteria depending on the market outlet or sales endpoint.
* Typically carrots are harvested at an immature state when the roots have achieved sufficient size to fill in the tip and develop a uniform taper.
* Length may be used as a maturity index for harvest timing of ‘cut and peel’ carrots to achieve a desired processing efficiency.

Maturity standards

Maturity standards have been determined for many fruit, vegetable and floral crops. Harvesting crops at the proper maturity allows handlers to begin their work with the best possible quality produce. Produce harvested too early may lack flavor and may not ripen properly, while produce harvested too late may be fibrous or overripe. Pickers can be trained in methods of identifying produce that is ready for harvest.

Other information

Root, bulb and tuber crops

Radish and carrot

Large enough and crispy (overmature if pithy)

Potato, onion, and garlic

Tops beginning to dry out and topple down

Yam bean and ginger

Large enough (overmature if tough and fibrous)

Green onion

Leaves at their broadest and longest

Fruit vegetables

Cowpea, yard-long bean, snap bean, batao, sweet pea, and winged bean

Well-filled pods that snap readily

Lima bean and pigeon pea

Well-filled pods that are beginning to lose their greenness

Okra

Desirable size reached and the tips of which can be snapped readily

Fruit vegetables

Upo, snake gourd, and dishrag gourd

Desirable size reached and thumbnail can still penetrate flesh readily (overmature if thumbnail cannot penetrate flesh readily)

Eggplant, bitter gourd, chayote or slicing cucumber

Desirable size reached but still tender (overmature if color dulls or changes and seeds are tough)

Sweet corn

Exudes milky sap when thumbnail penetrates kernel

Tomato

Seeds slipping when fruit is cut, or green color turning pink

Sweet pepper

Deep green color turning dull or red

Muskmelon

Easily separated from vine with a slight twist leaving clean cavity

Honeydew melon

Change in fruit color from a slight greenish white to cream; aroma noticeable

Watermelon

Color of lower part turning creamy yelow, dull hollow sound when thumped

Flower vegetables

Cauliflower

Curd compact (overmature if flower cluster elongates and become loose)

Broccoli

Bud cluster compact (overmature if loose)

Leafy vegetables

Lettuce

Big enough before flowering

Cabbage

Head compact (overmature if head cracks)

Celery

Big enough before it becomes pithy

References:

http://postharvest.ucdavis.edu/Produce/ProduceFacts/

usna.usda.gov/hb66/126sapodilla.pdf

http://www.sugarcanecrops.com/crop_growth_phases/ripening_maturation_phase/

http://www.fao.org/Wairdocs/X5403E/x5403e03.htm#maturity%20standards

Tags: Maturity indices