Physiological Maturity in Soybean<sup>1</sup>

TeKrony, D. M.; Egli, D. B.; Balles, John; Pfeiffer, T. W.; Fellows, Robert J.

doi:10.2134/agronj1979.00021962007100050016x

Cited by 75 publications

(49 citation statements)

References 13 publications

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“…The loss of green color in seed coats and embryos has been used as an indicator of seed maturation (10,17). However, the loss of embryo green color was not directly related to the timing of physiological maturity or to the changes in water relations observed in our studies.…”

Section: Discussioncontrasting

confidence: 58%

“…This indicates that the capacity for growth was limited by resistance to cell and tissue expansion, probably imposed by the pod and seed coat, in addition to slower solute transport. Although relative water contents of 60% or lower correlated with the cessation of embryo growth in the present study and in other work (8,17), embryo maturation can occur at 57 to 71% water content (1 1).…”

Section: Discussioncontrasting

confidence: 56%

“…Physiological maturity, as indicated by maximum seed dry weight, relative water content <60%, and loss of green color from embryo tissues (8)(9)(10)17), occurred at 58 to 60 DAF in the greenhouse (Fig. IA).…”

Section: Water Relations During In Situ Seed Growth and Maturationmentioning

confidence: 99%

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Soybean Seed Water Relations during in Situ and in Vitro Growth and Maturation

Saab¹,

Obendorf²

1989

Plant Physiol.

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Water, osmotic, and pressure potentials of soybean (Glycine max [L.] Merrill) embryos and related matemal tissues were measured during periods of seed growth and maturation to test the involvement of embryo water relations in seed maturation. Seeds were matured in situ or in an in vitro liquid culture medium in detached pods or as isolated seeds. Changes in water relations of embryo tissues were independent of maternal tissues. During seed maturation in situ, water and osmotic potentials in both embryo and maternal tissues declined sharply near the time of maximum dry weight. During in vitro seed culture with and without pods, water and osmotic potentials in axis and cotyledon tissues declined continuously during growth. Water and osmotic potentials of the seed coat, which was present only during in vitro seed culture with pods, changed little during the culture period. Positive turgor in the embryo was maintained beyond maximum dry weight and the loss of green color during in vitro culture but declined to zero at maturity in situ. The osmotic potential in embryo tissues declined from -1.1 megapascals at early pod fill to between -1.65 and -2.2 megapascals at maximum seed dry weight across all maturation environments. It is suggested that the decreasing osmotic potential in the growing soybean embryo reaches a threshold level that is associated with cessation of growth and onset of seed maturation.Seed growth and transport to embryos have been studied extensively (3,13,18,23), but regulation of seed maturation, and in particular, the role of seed water relations in growth cessation is not understood.In several crop species, water relations of embryo and endosperm tissues were independent of water relations of maternal tissues and of external environmental factors during seed development. In developing bean (Phaseolus vulgaris L.) seeds, water and osmotic potentials ofembryo tissues changed independently of maternal tissues (25). Maize (Zea mays L.) kernel water relations were unaffected by imposed water deficits that caused significant declines in water and osmotic potentials of leaves (12,22 and osmotic potentials declined during late growth and maturation in both wheat (1) and maize (21).Increasingly, evidence is pointing to the regulation of solute availability to developing embryos and endosperm by water relations of the embryo itself and the surrounding medium (2, 13, 18, 19, 23) (and others). Although solute unloading rates from seed coats varied considerably with the osmolality of the receiving medium in P. vulgaris L. (13), faba bean (Vicia faba L.), and pea (Pisum sativum L.) (23), sucrose unloading rates from attached soybean seed coats were reduced only at trap solution concentrations over 500 mM (18).Assimilate uptake also may be regulated by water relations inside the embryo. Guldan and Brun (2) reported that rates of asparagine uptake into excised cotyledons of field grown soybean (Glycine max [L.] Merrill) were lowered when the tissue osmotic potential was reduced to -1.8 MPa and below. On...

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Section: Discussioncontrasting

confidence: 58%

Section: Discussioncontrasting

confidence: 56%

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Soybean Seed Water Relations during in Situ and in Vitro Growth and Maturation

Saab¹,

Obendorf²

1989

Plant Physiol.

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“…Pods were sampled biweekly from 22 d after anthesis (beginning of the linear seed filling period) through 57 d after anthesis when most seeds had reached physiological maturity (19). Tagged pods were removed from the center nodes of three plants in each replicate between 0800 and 0900 h on each sampling date.…”

Section: Methodsmentioning

confidence: 99%

Abscisic Acid and Its Relationship to Seed Filling in Soybeans

Schussler¹,

Brenner²,

Brun³

1984

Plant Physiol.

134

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ABSTRACrThe effect of exogenous abscisic acid (ABA) on the rate of sucrose uptake by soybean (Glycine max L. Men.) embryos was evaluated in an in vitro system. In addition, the concentrations of endogenous ABA in seeds of three soybean Plant Introduction (PI) lines, differing in seed size, were commpared to their seed growth rates. ABA (10-molar) stimulated in vitro sucrose uptake in soybean (cv 'Cly') embryos removed from plants grown in a controled environment chamber, but not in embryos removed from field-grown plants of the Sink strength describes the capacity ofan organ to accumulate photoassimilates, and is the product of sink size and sink activity (25). Plant hormones are probably involved in determining both sink size and sink intensity. While cytokinins, gibberellins, and auxins generally promote growth processes, ABA has most often been considered an inhibitory substance (24). However, promotive effects of ABA in sink tissues have now been reported. ABA enhanced sugar content in roots of intact bean plants, possibly by stimulating sugar transport from the shoot to the root (11). In some cases, applications of ABA to ears of wheat (7) and barley (22) have stimulated 14C assimilate transfer from the flag leaf to the ear. However, King and Patrick (12) saw no stimulation of 14C transport to wheat ears after injection of ABA into the grains. Correlations between rate of growth and ABA accumulation in major sinks have been reported for wheat (13,14), grapes (5), pea (3), bean (10), and soybeans (4, 15). The relatively high levels (up to 12.2 #g g-' fresh weight) (15) and timing of ABA accumulation in soybean seeds (1,4,15) suggest a role in seed growth above simply preventing precocious germination. Browning (3) found that ABA accumulated more rapidly in a lare-seeded pea line and suggested a role for ABA in controlling cotyledon enlargement during linear seed fill. It has also been suggested that ABA may stimulate phloem unloading (8, 18) by decreasing the proton motive force across the sieve tube plasmalemma. The embryo-seed coat interface of the soybean seed (21) In addition, the endogenous ABA concentrations of seed coats, cotyledons, and embryonic axes of three field-grown soybean PI lines differing in seed size were compared to their seed growth rates during filling. MATERIALS AND METHODSGrowth Chamber Study. Plant Culture. Variety 'Clay' soybeans (Group 00 maturity) were grown in a controlled environment chamber in 1-L plastic pots in a 1.5:1.5:1 (v/v/v) mixture of vermiculite, peat, and sand. Pots were watered twice daily with automatic drip irrigation and given 250 ml of Peters 20-20-20 (200 ppm) twice weekly. A 14-h photoperiod with a 25/19C day/night temperature regime was provided. The photosynthetic photon flux density at the top of the canopy was 800 jE m-2 s-1.In Vitro Sucrose Uptake. During mid pod fill (seed dry weight 40% of final seed dry weight) pods were removed. Seed coats were surgically removed from a number of seeds and groups of three embryos were placed in 15 ml of sterile 10 ...

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“…15). Translocation of sucrose from photosynthate into the embryo ceases when the seed coat changes from green to yellow and seed respiration declines rapidly (TeKrony et al, 1979). Likewise, cotyledons cease to take up sucrose when the cotyledon color changes from green to yellow (Vernooy et al, 1986).…”

Section: Accumulation Of Soluble Carbohydrates During Seed Developmentmentioning

confidence: 99%