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III. Origin, Taxonomy, Cytology, and Plant Description

III. Origin, Taxonomy, Cytology, and Plant Description

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PRODUCTION AND BREEDING OF LENTIL



287



Figure 1. Typical habitat of wild L. orienrulis.



tivated species L. culinaris, is widely accepted as the progenitor species. L. culinaris ssp. orientalis has an extended range and can be found throughout the Near

East and as far east as Afganistan. The species is found in rocky and stony habitats

with very little soil (Fig. 1) and in association with other annual legumes, such as

the medics, and annual grasses. The conclusion that the cultivated lentil originated

in the Near East arc from L. culinaris ssp. orientalis is based on discoveries of

carbonized remains of apparent cultivated lentils in the same region over which

L. culinaris ssp. orientalis is distributed. Such carbonized remains have appeared

in early Neolithic settlements that date back to 7000-6000 BC (Helbaek, 1959).

Evidence for the center of origin and domestication of lentil has been reviewed by

Ladizinsky (1979a, 1993).



B. TAXONOMY

Cultivated lentil ( L . culinaris) belongs to the genus Lens which is associated

with other genera of the Vicieae tribe (Kupicha, 1981). The Vicieae tribe comprises Lens, Vicia L., Pisum L., Lathyrus L., and Vavilovia A. Fed. Cicer L. had



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previously been considered as part of the Vicieae, but anatomical and morphological evidence indicates that Cicer is quite different from other members of the

tribe and it is now classified in the monogeneric tribe Cicereae Alef. (Kupicha,

1975, 1977; Clarke and Kupicha, 1976).

In the Vicieae, Lens is described by Davis and Plitmann (1970) as holding a

position that is intermediate between Vicia and Lathyrus, but closer to Vicia sec.

Ervum. Lens is distinguished from Vicia by calyx morphology, stylar characters,

and pod and seed shape. The calyx tube in Lens is subequal while the calyx tube

is oblique in Vicia. Other calyx traits that distinguish the two genera include the

lengths of the calyx teeth relative to the corolla tube.

The primary gene pool of L. culinaris comprises ssp. culinaris and its presumed wild progenitor ssp. orientalis (Ladizinsky, 1993). Three other wild Lens

species are recognized in the secondary gene pool and include L. odemensis Ladizinsky, L. nigricans (M. Bieb.) Godron, and L. ervoides (Brign.) Grande.

Medikus is considered the authority for cultivated lentils because the publication of L. culinaris Medikus predates that of L. esculenta Moench. (Slinkard,

1974). L. montbretii (Fischer and C. Meyer) Davis and Plitm. has been removed

from the genus Lens based on the work of Ladizinsky and Sakar (1982) and placed

in the genus Vicia. Morphological and karyological information indicated considerable divergence between L. montbretii and other Lens species. Their foremost

observation was that L. montbretii has 2n = 12 chromosomes whereas the other

Lens species have 2n = 14. Based on that information, it is clear that L. montbretii

is more appropriately classified as a species of Vicia. For karyotypes of L. culinaris, L. nigricans, and L! montbretii see Ladizinsky ( 1 993).

Stipule shape is a major characteristic used to distinguish the wild Lens species

(Ladizinsky et al., 1988). L. culinaris ssp. orientalis has stipules that are lanceolate entire and similar to those of L. culinaris ssp. culinaris and L. ervoides. L.

nigricans and L. odemensis have semihastate or dentate stipules. The stipules of

L. nigricans are oriented parallel to the stem while those of L. odemensis are

oriented perpendicular to the stem and is a distinguishing feature used to differentiate between the two species (Ladizinsky, 1993).

Synonyms used by Barulina (1930) for the Lens species include: L. esculenta

Moench for L. culinaris; L. lenticula (Schreb.) Alefed. for L. ervoides; and L.

kotschyana (Boiss.) Alefed. for L. montbretii (now L! montbretii). A more complete list of synonyms can be found in Barulina (1930) and in Cubero (198 1).



C. CYTOLOGY

All Lens species are diploid annuals with 2n = 14 chromosomes. They also

have similar karyotypes consisting of three pairs of metacentric or submetacentric

chromosomes, three pairs of acrocentric chromosomes, and one satellited pair



PRODUCTION AND BREEDING OF LENTIL



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of chromosomes (Sharma and Mukhopaday, 1963; Ladizinsky, 1979a; Slinkard,

1985). The karyotypes of L. culinaris and L. nigricans have been presented by

Ladizinsky (1993).



D.



I”T



DESCRIPTION



Plants of L. culinaris ssp. culinaris are herbaceous annuals with slender stems

and branches (Fig. 2 ) . Plant height usually ranges from 25 to 30 cm for the ma-



Figure 2. Typical plant of L. culinaris.



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F. J. MUEHLBAUER ET AL.



jority of genotypes, but may vary from 15 to 75 cm depending on genotype and

environmental conditions (Saxena and Hawtin, 198I). Plants have a slender tap

root with fibrous lateral roots. Rooting patterns range from a much-branched shallow root system to intermediate types that are less branched and more deeply

rooted (Nezamuddin, 1970).The tap root and lateral roots in surface layers of the

soil have numerous, indeterminate nodules that vary in shape from round to elongate (Saxena and Hawtin, 1981).

The herbaceous stems of lentil plants are square and ribbed and are usually thin

and weak. Primary branches arise directly from the main stem and may emerge

from the cotyledonary node below ground or from nodes above ground. Secondary branches arise from primary branches, but plant habit is plastic depending on

available space; the number of primary and secondary branches can vary depending on the genotype, the stand density, and prevailing environmental conditions

(Malhotra et al., 1974; Wilson and Teare, 1972).

The leaves are relatively small compared to those of other large-seeded food

legumes. They are described as pinnate or imparipinnate and comprise as many

as 14 sessile, ovate or elliptic, or obovate or lanceolate leaflets that vary in length

from 1 to 3 cm. Each leaf is subtended by two small stipules and it may or may

not terminate in a tendril. The entire stipules are oblong lanceolate and unappendaged (Davis and Plitmann, 1970; Summerfield et al., 1982).

The flowers are borne singly or in multiples on peduncles that originate from

the upper nodes of the plant. Each peduncle normally bears from one to three,

rarely four, flowers, although seven flowers per peduncle have been reported for

plants grown in a controlled environment (Hawtin, 1977).

The individual flower is complete and has a typical papilionaceous (“butterflylike”) structure (Fig. 3). Flowers are small (4 to 8 mm long), white, pale purple,

or purple blue. The flower has a calyx comprised of five equally elongated sepals



Figure 3. Typical lentil flower (A) and pods and seeds (B).



PRODUCTION AND BREEDING OF LENTIL



291



that equal or exceed the length of the corolla of the unopened flower. The corolla

has a standard two wings and two lower petals that lie internal to the wings and

are united at their lower margin to form the keel (reviewed by Muehlbauer et al.,

1980; Summerfield et al., 1982). The stamens are diadelphous (9 + 1) with the

upper vexillary stamen free. The ovary is flat and glabrous; it normally contains

one or two ovules that alternate along the margin and terminate in a short curved

style. The style is pilose on the inner side, it usually develops at a right angle to

the ovary, and is flattened on the outer side (reviewed by Muehlbauer et al., 1980;

Saxena and Hawtin, 1981; Summerfield et al., 1985).

The fruits (referred to as pods) are oblong, laterally compressed, 6 to 20 mm

long and 3.5 to 1 1 mm wide, and usually contain one or two, rarely three, seeds

(Saxena and Hawtin, 1981).

Seeds are lens shaped and weigh between 20 and 80 mg. Seed diameter ranges

from 2 to 9 mm and the testa may be light green or greenish red, gray, tan, brown,

or black. Purple and black mottling and speckling of seeds are also common in

some cultivars and accessions (Duke, 1981; Saxena and Hawtin, 1981; Vandenberg and Slinkard, 1990). Seed size differs according to genotype, and researchers

frequently follow the classification of Barulina (1930), who grouped lentils as:

“macrosperma” with large seeds that range from 6 to 9 mm in diameter and

“microsperma” with smaller seeds that range from 2 to 6 mm in diameter. The

macrosperma types are common to the Mediterranean basin and in the Western

Hemisphere, while the microsperma predominate throughout the Indian subcontinent and in parts of the Near East. Other groupings of cultivated lentils have

been described and include europeae, asiaticae, intermediate, subspontaneae,

aethiopicae, and pilosae. Detailed descriptions of these groups are available in

Muehlbauer et al. (1985).



IV.PRODUCTION OF LENTIL

A. LANDREQUIREMENTS

In the United States, lentil crops are sown in the spring in rotations that include

winter wheat and barley. Lentils are commonly followed by winter wheat which

is planted in the fall because the land is in very good condition following the

legume. In the Palouse region, soil moisture is usually fully recharged by fall and

winter precipitation. Barley, which is usually spring sown, follows the winter

wheat crop. Alternatively, the lentil crop is planted in alternate years with winter

wheat in a 2-year rotation.

Lentil crops in the Palouse have better yields when they are planted on well-



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drained soils on south- and east-facing slopes. Yields on the tops of the usually

eroded hills are poor when compared to that obtained on the slopes. However,

yields in the low-lying areas of fields can also be poor because of an excess of

fertility and moisture. Under such conditions the lentil crop develops abundant

amounts of vine and foliage at the expense of seed yield.



B. SEEDQUALITY

AND SEEDTREATMENT

For optimum stands and yields it is recommended that producers use certified

seed with greater than 90% germination and treated with seed protectants. Foundation, registered, and certified seed of improved cultivars is generally available.

Seed treatments with appropriate fungicides such as Captan ' or Apron aid in preventing damping-off and ensure good stands. Treatment of the seed with an insecticide such as Lindane is beneficial for the control of wireworms and seedcorn

maggots. Molybdenum is often applied to the seed along with other seed dressings. Molybdenum is recommended for crops in the Palouse region, where the

soils are known to be deficient in the element and where the crop is known to

respond to small amounts when applied to the seed. In areas where there is no

deficiency, the crop is not likely to respond.

Lentils require inoculation with the proper strain of Rhyzobium leguminosarum

for good root nodulation and dinitrogen fixation. When planting fields for the first

time or when there has been a period of time without lentil, it is important for

good fixation that the crop be inoculated.

Seeds of K sativa have occasionally appeared in seed lots of lentil harvested

throughout the region. Vicia seeds are unwanted contaminants found in many lentil landraces. These contaminants are inadvertently carried with seed that is used

to plant new production areas (Erskine et al., 1994). The seeds of the Vicia contaminants have approximately the same size, shape, and color as the germ plasm

that they contaminate. These Vicia rogues can be distinguished by their blunt seed

edges and by the hilum area which is generally more pronounced than in lentil.

In the field, Vicia rogues are conspicuous for their large blue or purple flowers, pointed pubescent leaflets, and elongated pods containing six to eight seeds.

Vicia seeds are considered contaminants in lentil crops and contribute to reduced

grades; however, the Vicia rogue problem can be greatly reduced or eliminated by

the use of certified seed. Hard seeds of the Vicia and their germination in lentil

seed fields over a period of years are the primary means of contamination of seed

stocks.

'Mention of this trade name or any other trade names does not imply endorsement by the

USDA-ARS to the exclusion of other products which may also be effective.



PRODUCTION AND BREEDING OF LENTIL



293



C. SEEDBED

PREPARATION

Land intended for lentil is usually rough tilled in the fall either by mold board

or chisel plowing. The latter is recommended in order to keep previous crop residues on the soil surface to reduce soil erosion. Fall tillage is recommended to

promote water infiltration into the profile and reduce runoff (Papendick and Miller, 1977). When soils are sufficiently dry in the spring, fields are harrowed and,

after one or two tillage operations, herbicides are applied and incorporated by

cross tillage. Soil temperatures above 6”C are needed for good germination and

seedling growth.



D. SEEDING

Lentils are often planted as early as possible in the spring with the same equipment used to plant cereals. The yield advantage from early spring planting can be

substantial, provided seeds are not planted when the soil is too wet (Muehlbauer

and Slinkard, 1981). Seeding depths of 4 to 5 cm are optimal for germination and

growth, but deeper plantings are sometimes used either to provide better access to

soil moisture or to place the seeds below the zone of incorporated herbicides.

Despite some success with deeper plantings, particularly when soils are dry, lentils

do not generally emerge well from deep planting, especially if the soils become

crusted from heavy rains.

Lentil seeds can germinate in light or in darkness and in constant or fluctuating

temperature regimes. However, the rates of germination, emergence, and seedling

growth are markedly affected by temperature (Summerfield et al., 1982). Optimum rates of germination and growth vary with cultivar, age, and size of seeds;

smaller-seeded cultivars germinate more rapidly than larger ones at temperatures

between 15 and 25°C (Saint-Clair, 1972).

The successive stages of canopy formation (stem elongation, leaf initiation, leaf

expansion, and branching) have different optimal thermal regimes (Summerfield,

198I ). This may help explain the so-called “dormant phase” referred to by farmers in which lentil seedlings, once emerged, often grow slowly, for several days or

even weeks. This indicates that successive stages of vegetative development have

warmer temperature optima.

Lentil yields are remarkably stable over a wide range of population densities;

the plants are able to fill available space by initiating lateral branches and can

readily compensate for poor emergence and thin stands. Recommended seeding

rates for farmers in the Palouse region of the United States are 65 to 80 kg ha I

for the most commonly grown cv. ‘Brewer.’ Elsewhere, seeding rates vary from

15 kg ha - I for the microsperma types used in northern India to 115 kg h a - ’ for

~



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F. J. MUEHLBAUER ET AL.



the larger-seeded types used for irrigated crops in Egypt (Hawtin et al., 1980).

Optimum plant density has been estimated (Muehlbauer, 1973) at 90 plants m - 2 .

Smaller-seeded cultivars appear to have greater tolerance to drought; they generally mature earlier than larger-seeded cultivars and avoid drought stress. In

many of the dry regions of the world, the smaller-seeded cultivars, with their

earlier maturities, are prevalent, possibly because they are considered more tolerant of drought and are able to avoid extreme water stress. The development of

drought-tolerant cultivars has been given priority in lentil research programs in

dry areas.



E. LENTILCULTWARS

Lentil cultivars with improvements for one or more traits have been developed

at a number of locations throughout the world. The most prominent program in

lentil breeding was established in 1978 and is located at ICARDA located in

Aleppo, Syria. That program has a world mandate for the genetic improvement of

the lentil crop. Major emphasis has focused on the harvesting problem in traditional production areas and the need to develop germ plasm and cultivars that

can be harvested mechanically. Improved germ plasm is provided to programs

throughout the world for use in breeding programs. The ICARDA program has

been active in the collection and preservation of wild Lens species in the center of

origin and in the collection of landraces in the traditional production areas.

The lentil cultivars released prior to the 1980s were mostly selections from

germ plasm collections and were not from hybridization programs (Hawtin et al.,

1980). However, current national and international lentil improvement programs

now provide improved resources for hybridization and selection. These programs

acknowledge the importance of collecting, introducing, exchanging, and maintaining germ plasm to provide as wide a range of genetic diversity as possible for

breeding programs. Improved cultivars with a larger yield potential have been a

direct result of these efforts.

Cultivars used by growers in the Palouse have undergone a transition from an

introduced landrace (‘Chilean’) that was used to initiate commercial production

in the 1930s to cultivars developed by pure line selection and, more recently, from

hybridization. The cultivars in use in the United States are described as follows.

‘Chilean 78’ is a composite of pure line selections from ‘Chilean’ which were

made to remove unwanted variation and Vicia rogues from the seed stock. The

Chilean stock from which the selections were made was the most commonly

grown type in the region until the release of Chilean 78.

‘Brewer,’ released in 1984 (Muehlbauer, 1987), has largely replaced common

Chilean and Chilean 78. Brewer has uniform large seeds with yellow cotyledons



PRODUCTION AND BREEDING OF LENTIL



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and is 4 to 7 days earlier to mature when compared to Chilean 78. Brewer has

consistently given higher yields when compared to Chilean 78. At present, it is

the main cultivar grown in the Palouse region and occupies over 90% of the

production area.

‘Redchief‘ is a large red cotyledon type with nonmottled seed coats (Wilson

and Muehlbauer, 1991). Yields of Redchief have been consistently better than

Chilean or Chilean 78. Large red cotyledon types are entirely new and it has been

necessary to develop markets for the Redchief type. The demand for the large red

type has slowly but consistently increased in the United States.

‘Emerald’ is a bright green-seeded cultivar with distinctive green cotyledons

(Muehlbauer, 1987). Production of Emerald has been extremely limited because,

similar to Redchief, market demand needs to be created for green cotyledon types.

‘Palouse’ is a yellow cotyledon cultivar with large seed size, an absence of seed

coat mottling, and early maturity (Muehlbauer, 1992). It produces yields comparable to Brewer and even though it is larger seeded it has resistance to mechanical

damage during threshing and processing.

‘Crimson’ is a small-seeded, red cotyledon cultivar (Muehlbauer, 199I). Crimson is well adapted to Palouse conditions and gives comparable yields to Brewer;

however, the cultivar also performs well in drier areas. Crimson was derived

by pure line selection from ‘Giza-9,’ a cultivar developed in Egypt. Crimson

was developed for use as an export commodity for markets that prefer the small

red type.

‘Tekoa’ was the first lentil cultivar to be released in the United States (Wilson

et al., 1971). The cultivar has large nonmottled seeds with yellow cotyledons. The

cultivar has not been widely grown in the United States because of excessive

amounts of mechanical damage during harvesting and processing. However, Tekoa has been produced successfully in Chile where its apparent resistance to rust

has given the cultivar a distinct advantage.

‘Spanish Brown’ or ‘Pardina’ is a small yellow cotyledon cultivar with brown

and speckled seed coats. The cultivar was introduced from Spain and is now being

produced extensively in the Palouse. It has produced exceptionally good yields;

however, recent observations indicate susceptibility to Ascochyta blight caused by

Ascochyta fabae f. sp. lentis.

Cultivars developed in Canada include ‘Laird’ (some Ascochyta blight resistance with large, yellow cotyledon, nonmottled seed) (Slinkard and Bhatty, 1979),

‘Eston’ (small, pale-colored seed), ‘Rose’ (red cotyledons), and ‘Indian head’

(small seeded with black seed coats; used primarily as a green manure lentil).

Cultivars developed elsewhere include ‘Precoz’ (an early maturing cultivar) from

Argentina (Riva, 1975); ‘Araucana-INIA’ (rust tolerant) from Chile (Tay et al.,

1981); ‘Pant L-234’ (Fusariurn resistant) (Kamboj et al., 1990), ‘Pant-209,’ and

‘Pant-406’ from India; and Giza-9 from Egypt (Hawtin et al., 1980).



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V. FERTILIZATIONAND WEED CONTROL

A. FERTILIZERS

Nutrient requirements of lentil crops have not been adequately determined for

the major lentil production areas. However, certain applications have been worthwhile. The periodic use of molybdenum as a seed dressing in the Palouse region

of the United States is essential for good nodulation and dinitrogen fixation.

Applications of sulfur are important for increasing concentrations in the seeds

of sulfur-containing amino acids which are nutritionally limiting in lentil seeds.

Phosphorus is applied to ensure good symbiotic performance and overall plant

growth. Occasionally potassium is applied. Application rates of fertilizers recommended to growers are:

Molybdenum: Sodium molybdate applied as a seed dressing at 35 g ha -I.

Sulfur: Applied to other crops grown in rotation with lentils at 17 to 22 kg

ha - I on deficient soils.

Phosphorus: If soil tests (acetate extraction method) reveal phosphorus concentrations at 4 parts per million (ppm) or less, it is recommended that 44 to

66 kg ha - I be applied. Responses to phosphorus applications are commonly

evident on severely eroded soils.

Potassium: On sandy or severely eroded soils, 22 kg ha - I of potassium oxide

has proved beneficial for yield and may also improve the cooking qualities of

seeds (Wassimi et al., 1978).

Nitrogen: Well-nodulated lentil crops seldom respond to applications of inorganic N fertilizer.

The “nitrogen hunger” phase, which is often experienced by grain legumes

when crops are seeded early into cool, wet soil before significant symbiotic dinitrogen fixation begins, can be avoided by the application of a small starter dose of

10-25 kg ha - I inorganic nitrogen placed adjacent to, but not in contact with, the

seeds (Saxena, 1981).

Inoculation with an appropriate strain of R. leguminosarum is necessary when

lentils are seeded into fields for the first time or after a lapse of several years.

Special care should be taken when using fungicide seed dressings potentially toxic

to Rhizobium.



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B. WEEDCONTROL

Lentils are poor competitors and good weed control is essential for successful

production. Lentil growth rates are slow during early stages of vegetative growth

and weeds can quickly overgrow the crop if not adequately controlled.

Hand weeding is practiced in traditional production areas, but is impractical in

the extensive production systems used in the United States. It is therefore necessary that effective herbicides be used to reduce unwanted competition.

Certain herbicides have been effective in controlling broadleaf and grass type

weeds in lentil crops; however, only a limited number are registered for use in the

United States. Wild oat can be controlled with preplant-incorporated applications

of triallate (Far-go). However, triallate does not control other annual grasses. After

crop emergence, sethoxydim (Poast) applications control both annual and perennial grass weeds.

For broadleaf weed control, imazethapyr (Pursuit) can be applied prior to planting, followed by shallow incorporation or applied preemergence soon after planting. Metribuzin (Lexone/Sencor) can be applied preemergence, postemergence,

or as a split application. Metribuzin gives good or excellent control of a wide

spectrum of broadleaf weeds with few exceptions. Reemergence applications of

both herbicides require adequate rainfall in order to distribute the herbicide into

the zone where weed seeds germinate. Under conditions of excessive rainfall and

on soils with minimal organic matter, metribuzin may leach deeper into the profile

and cause crop injury. Injury is the most severe on the tops of eroded hills where

soils have minimal organic matter and where lentils may have been seeded too

shallow. Dry conditions reduce the effectiveness of soil-active herbicides and

weed control may be poor.



VI. PRINCIPAL USES

A. FOOD

A major food use of lentil is as dhal, decorticated and split lentils, which is a

principle ingredient in soups and other dishes prepared on the Indian subcontinent.

Besides their use in soups, whole lentil seeds are often ground into flour and added

to cereal flour in the preparation of breads and other baked products. Lentils are

also used in dishes containing rice and cereal grains. When combined with cereal

grains, lentil provides a nutritionally well-balanced diet for consumers. The relatively large concentrations of lycine compensate for the minimal concentrations



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