Physiological studies of the growing process of broad bean plants. V. Effects of shading on the growth and the chemical components in the various organs-香川大学学術情報リポジトリ

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Vol. 23, No 2 (1972)

PHYSIOLOGICAL STUDIES O F T H E GROWING PROCESS O F BROAD BEAN PLANTS

V Effects of Shading on the Growth and the Chemical Components in the Various Organs

Kiyoshi TAMAKI and Junzaburo NAKA

BLACKMAN and BLACK(^) have examined the analyses of the effects of shading on the growth and development in the vegetative phase of many herbaceous species, and recognized that the net assimilation rate of the broad bean (Vzcza faba) was directly related to the logarithm of the light intensity And when the degree of shading increased to 0 055 daylight the logarithmic relationship still held though this level was below the compensation point, therefore, broad bean would be classed as intolerant of deep shade, they also stated. O n the other hand, for one out of many reasons of the phenomena with flower- and early pod-wastage of the broad bean plants especially cultured in a dense population, SO PER(^^) suggested the lack of specific growth substances and the shortage of carbonaceous substrates due to light inhibition. I n this respect, HODGSON and BLACK MAN(^) reported that though the concept of competitive ability between the various organs was generally accepted, there was still no proper understanding of the mechanisms in- volved in the pattern of distribution or redistribution of essential substrates within the plant.

As stated above, the present investigation is an attempt to obtain some informations concerning the effects of shading on the growth, the dry matter production, and the physiological status es- pecially carbohydrate and nitrogen contents in the various organs of broad bean plants

Materials and Methods

Broad bean, cultivar "Sanuki-nagasaya", were sown a t nursery bed on November 6 and the Early stage Floweritlg stage Maturing stage

- r

-

-.

-

at tlie at the at the at the at the transplanting start of end of green,pod time of

flowering floweritig maturkng maturity

ccc

I

1

csc

1

m

-

I

ccs

css

7

-SCC

1

scs

-

-S -S C

C

I

sss

Control

-1

(natural dayligllt)

-

Shading

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158 Tech.. Bull. Fac. Agr. Kagawa Univ. seedlings were transplanted two plants per pot on November 30. Each pot received 1.9 g am- monium sulfate, 3 5 g calcium superphosphate, and 1 2 g potassium sulfate. Soil moisture was maintained about 75 per cent of field capacity.

The experimental design is shown in Fig 1

,

the shading were operated in three stages; early, flowering, and maturing Accordingly, plants were subjected to eight treatments including natural daylight (control) condition The shading was accomplished by mounting in horizontal position 180 cm above the ground and by surrounding with open-mesh cloth in a glass-roofed wire-mesh house. For light intensity, readings taken with Toshiba Lux-meter (No. 5) revealed about 30 per cent of the control throughout the treated period, but the temperature was low 2 to 4°C and the relative humidity was high 5 per cent than that in the control Plants were sampled a t four times. The sampling techniques and other experimental details of chemical analysis were the same as described in the previous papers(l3.14).

Results Growing Process

Growing status of plants are shown in Figs 2 and 3 I n the early stage, the shading hastened the elongation of main stem and postponed the branching, subsequently there were inequality in stem length compared with the control; at the start of flowering, the length of main stem was 30-6 cm and those offour branches were 32 4, 32.5, 24 4, and 15.7 cm respectively in the control plant, but the treated plant had 55 5 cm in main stem and 38 1, 24.0, and 15 4 cm in three branches, The shading in the flowering stage or the maturing stage increased the stem length but decreased the leaf number and retarded the development of root nodules. Moreover, plants which were encountered low light intensity in the flowering stage, became secondarily vigorous when plants were kept under the unshaded condition in the maturing stage

0---0 Control

t

-

-e

Shading

Dec, Jan. Feb. Mar. Apr. May Jun.. Fig. 2. Changes in total stem length per plant Fig. 3. Changes in total leaf number per plant The flowering began later about one week by the shading in the early stage than that of the control, and pod bearing stem number and flower number were also considerably reduced. The shading in the flowering stage declined the flower number and elevated the flowering and podding node position. If those plants were kept under the unshaded condition in the maturing stage,

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Vol. 23, No.. 2 (1972) 159 however, the flowers and pods were found on the more upward nodes accompanying with the secondary growth. The shading in the maturing stage induced the reduction of pod and seed development, and those effects were severe than the continuous shading (Table 1 .).

Table 1 Effects of shading on the flower, pod, and seed

CCC CSC CCS CSS SCC SCS SSC SSS pod number

*

a t the start 3 5 8 1 4 5 3 5 8 14 5 23 8 23 8 14 8 14.8 of flowering pod number

*

at the time 123 8 5 8 3 6.5 7.3 5.0 8 0 5.0 of maturity 2) podding percentage % 154 134 1 0 4 10.3 14 1 9.7 26 0 16.2 pod length cm 10 6 8.8 8.3 8 2 103 9 2 9.5 9 9

seed number per 2 7 2 0 2 1 2.0 2 9 2.5 2 6 2.5

pod 100 seeds wt. g 97.3 93.7 90.5 100 5 111 7 102 6 91 9 106 7

*

per plant Seed P o d Leaf blade Stem 75

I-

Root nodule Root CCSS CSCS CCCCSSSS CSCS CCSS CCSSCSCS CSCSCCSS CCSSCSCS a t the at the at the start end at the time

of of green,pod of

flowering flowering maturlng maturity

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160 Tech Bull Fac. Agr Kagawa Univ

The dry weight per plant and its distribution of each organs at sampling times are shown in Fig. 4 The dry matter production in vegetative organs was lowered by the shading, especially in the early and the flowering stage. Moreover, even if the plants, which were encountered the shady condition, grew in the following stage under the unshaded condition, could not recover to the normal growth level O n the other hand, the dry weight of reproductive organs were lowered by the shading in the flowering or the maturing stage, especially in the later stage. As for the seed weight, however, among the eight treated plants, it was great in the control and the shading in the stage of early growth alone

Chemical Components

The variations of carbohydrate content per gram dry weight at four sampling times are shown in Figs. 5 and 6 Total carbohydrates in leaf blade and stem were lowered by the shading in every stage This tendency was emphasized in the content of sugars Especially, the sugar content in stems of the plants treated in the maturing stage, was lowered a t the green pod maturing, and this fact was basically different from other treated and control plants Similar results were obtained in roots and root nodules I n pods, the carbohydrate contents especially the starch was reduced by the shading As for the contents in seeds, however, evident differences could not be detected among any treatments

Reducing sugar

200 Non- reducing sugar

h 4

:

loo -2 0

E

4001 s t e m """ 100 0 CSCS CSCSCS CSCSCS at the at the CCSSCS CCSSCS start of end of at the green at the time

noweling flowering Podmaturing of maturity start of flowering end$ flowering pod at the green maturing

Fig 5. Carbohydrate content in leaf blade, Fig 6 Carbohydrate content in root nodule, pod,

stem, and root and seed

The variations of nitrogen content per gram dry weight at four sampling times are shown in Figs 7 and 8 Total nitrogen contents in leaf blades and stems were heightened slightly by the shading in all stages. With regard to the contents of soluble-N and protein-N, these increasing

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Vol. 23, No. 2 (1972) 161

effects by the shading were recognized in the soluble-N As for the underground organs, the soluble-N contents increased in roots but in root nodules the protein-N contents increased by the shading. O n the contrary, the variations of the total contents in pods and seeds had similar features among all treatments, and the soluble-N and protein-N contents had also little differences

,

Leaf blade

Y

S t e m

a t the s t a r t a t the end at the green a t the time of flowering of flowering pod maturing of matur~ty

Fig 7. Nitrogen content in leaf blade, stem, and root 1 Pod Seed 60 40 ,--. $ 20 X 4 0 M

2

CCSSCS CCSSCS C S C C S S C C C C S S C S C S C S C S C S C C S S C S

at the green a t the time pod rnaturlng of maturity

Soluble- N Protein-N

at the end at the start at the green of flowering of flower~ng pod matur~ng

Fig 8 Nitrogen content in root nodule, pod, and seed

Discussion

The eff'ects of shading or low light intensity on the growth of leguminous crops have been investigated; the thin and extensive leaves, few but long stems, less developed underground parts, low dry weight of organs, and poor flowers and pods were recognized(4.5~6~s~9~16) I n this experi- ment with broad bean plants, those were essentially similar to the results mentioned above A I H A R A ~ ~ ) indicated that though the considerable hard deficiency of light on broad bean variety "Issun" did not directly reduce the function of pollens, the low light intensity caused the deficiency of supplying the photosynthate, subsequently induced the retardation of plant growth and the development of flower I n the present experiment, the reductions of flower number seemed to be caused by the shortage of photosynthetic substances(l2), because the treated plants had weakly leaves of the 1 16 to 133

%

in leaflet-area and the 85 to 87% in thickness

O n the other hand, the relative growth rate (RGR) was lowered by the shading in two stages; from the start to the end of flowering and from the end of flowering to the green pod maturing (Table 2 ). The changes of R G R among eight treatments were due to those in the net assimila- tion rate (NAR) as the results of BLACKMAN and BLACK(^)

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Table 2 Effects of shading on the relative growth rate (R G R) g/g/wk -- - . - C C C C S C C C S C S S S C C S C S S S C S S S at the start of flowering & 0249 0 105 0 249 0 105 0 209 0 209 0 074 0074 at the end of flowering & 0132 0195 0017 0120 0202 0.068 0292 0181 at the green pod

maturing

The behaviors of net dry matter produced during the sampling stage are shown in Fig. 9. Dry matter production in vegetative organs was lowered by the shading in the flowering stage, especially in root. But in the following stage, the dry weight in certain organs of the treatment of C C S and S C S were rather decreased by the shading Moreover, the development of re- productive organs should be progressed instead of vegetative growth if the plant received insuf- ficient light intensity, as suggested in the previous paper (Is), the authors guessed from the results of dry matter distribution ratio.

Seed !Pod

3 Leaf blade

L -I

b-at the start b-at the end at the gIeen of flowering

+

pod maturing

4

at the end at the green at the time of flowering pod maturing of matu~ity

Fig. 9. The rise and fall of dry weight in each organ between the sampling times (per plant)

As for the chemical contents, the reduction of carbohydrates and the increase of nitrogen com- pounds with the treated plants in this experiment were essentially similar to the reports with other leguminous crops(2.10*11). The authors pointed out in the previous paper(l5) that the soluble portion/insoluble portion ratio in broad been plants was important to explain the growing process from the physiological standpoint From the results in this experiment, it can be considered

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Vol. 23, No. 2 (1972) 163 that the total sugarlstarch ratio was lowered by the shading with the exception of pods. The soluble-N

/

protein-N ratio, however, was lowered in organs with the exception of roots by the shading (Table 3 . ) .

Table 3. Effects of shading on the ratio of soluble and insoluble portion of chemical component in each organ

at the start at the end at the green pod

of flowering of flowering matur ing

,----"---

--

---.

- C S CC CS SC -SS --CCC CSC CCS CSS SCC SSS

Carbohydrate (total sugar / starch)

leafblade 2.64 1 3 1 130 137 0 9 8 120 1.29 141 1 0 1 151 1.24 1 2 0 stem 3 40 2.23 2 14 1 56 0 62 1 4 3 2.09 1 75 1 4 9 181 0 79 1.18 root 1 4 9 0.82 0 52 0 32 0.34 0 34 0 67 0 62 0 41 0.33 0 25 0.32 root nodule 2 47 1 39 1 58 0 93 0 75 0 97 1 07 0 81 1 00 1 0 8 0 78 0 8 6 pod

- -

1 6 6 550 044 3.11 0 8 5 1 1 8 1 1 2 171 0 4 5 140 -- Nitrogen compound (soluble-N / protein-N)

-. leafblade 0 5 0 0 4 6 0 5 0 0 4 6 0 4 3 0 5 0 0 4 9 0 5 1 0.47 0 4 9 0 4 6 0 4 5 stem 2 09 2 01 2 43 2 02 150 164 2 45 2 51 2 24 2 22 2.06 2.18 root 112 1 0 8 0 7 1 072 0 8 0 1.00 0 8 3 100 0.78 0 8 6 0.73 0 9 3 root nodule 0 76 0 64 0 93 0 75 0 73 0 51 1.03 0 96 0 82 0 91 0 96 0 6 2 pod

- -

1 14 0.90 0 90 0 92 2 29 2 27 2.13 1 8 5 1 59 1 8 8

O n the other hand, the authors pointed out in the previous papers(l3.14) that the stems, roots, and pods played the role as a temporary storing organ for the chemical components in seeds. With these assumptions, the variations of carbohydrate and nitrogen amounts per plant are shown in Fig. 10 Though the amounts in the vegetative organs plus pods generally became highest a t the green pod maturing, those were retarded by the shading in the flowering and the maturing

-

LM

Mar. Apr. May Jun CSCSCS CSCSCS

ccsscs CCSSCS

---ocontroi at the green at the ;,me

t- -a Shading pod maturing of maturity

Fig 10 Variations of total carbohydrate and nitrogen amount in the vegetative organs plus pod and seed (per plant)

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stage. The amounts of both components in seeds were also reduced by the shading after the flowering stage, especially in the maturing stage But even if the plants, which were encountered the shady condition in the early stage, grew under the unshaded condition in the following stage, the amounts in seeds became similar as in the control plants This fact may be imply when the vegetative growth and the temporary storage of the chemical component are poor with broad bean plants, the reproductive growth progresses in stead of the vegetative growth and thenceforth

a considerable amounts of substance synthesized in leaves and roots translocate directly into seeds. Therefore, it seemed that the shading for broad bean plants acted not only on the physiological status, but also on the assimilation, the storage, and the translocation of carbohydrate and nitrogen compounds.

Summary

I n the hope of catching some informations concerning the effects of shading on the growth and the chemical components of broad bean plants, the present investigation was undertaken using the cultivar "Sanuki-nagasaya" as material. The experiment was conducted under the conditions of low light intensity, about 30 per cent of natural daylight (control), in three stages of growing period The results obtained may be summarized as follows:

( I ) The shading induced the retardation of branching in the early stagc, the acceleration of stem lengthening and the reduction of leaf and flower number in the flowering stage, and the retardation of development of pods and seeds in the maturing stage However, those shaded plants grew secondarily when the plants were returned to the state of the natural daylight (control) in the following stage. The dry matter production was also reduced by the shading with a viewpoint of whole plants.

(2) The carbohydrate contents were lowered and the nitrogen contents were heightened by the shading especially in stems As for the soluble portion insoluble portion ratio of the vegeta- tive organs, they were generally low in the carbohydrates and in the nitrogen compounds O n the contrary, the temporary storage of chemical conponents in the vegetative organs plus pods were prevented by the shading, but when the vegetative growth was poor, the growth of the reproductive organs progressed with less dependence on the substance of vegeta- tive organs and a considerable amounts of synthetic substance stored directly into seeds from the assimilating organs

(3) Judging from the results obtained in this experiment, it may be pointed out that broad bean plants accumulate less of dry matter with low light intensity, and the shading acts not only on the physiological status, but also on the assimilation, the storage, and the translocation of chemical compounds.

Literature Cited

( 1 ) AIHARA, S : Studies on the flower dropping of ( 2 ) BEINHARI, G: Free sugar concentrations in broad bean, (1) Influences of the light defi- white clover, Trzfilzum repenr L , grown at dif- ciency on the dropping of flower, Tech. Bull ferent temperatures and light intensities, Crop

Mzyagi Prefectural Agr. Exp Sta , (28), 6-10 Scz , 4, 625-63 1 (1964)

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Vol. 23, No. 2 (1972)

and ecological studies in the analysis of plant environment, XI A further assessment of the influence of shading on the growth of different species in the vegetative phase, Ann Bot , 23, 51- 63 (1959)

( 4 ) BULA, R. J , RHYKERD. C L., LANGSTON R G :

Growth reyponse of alfalfa seedlings under vari- ous light regimes, Agron J , 51, 84-86 (1959) ( 5 ) COOPER, C S : Relative growth of alfalfa

and birdsfoot trefoil seedlings under low light intensity, Crop Sci., 7, 176-178 (1967)

( 6 ) GIST, G R , MOII, G 0 : Growth of alfalfa, red clover, and birdsfoot trefoil seedlings under various quantities of light, Agron J , 50, 583-

586 (1958)

( 7 ) HODGSON, G L , BLACKMAN, G E : An analy- sis of the influence of plant density on the growth of Vzcza faba, I1 The significance of competition for light in relation to plant develop- ment at different densities, J exp Bot, 8, 195- 219 (1957)

( 8 ) IDLE, D B : Studies in extension growth, I1 The light-growth responses of Vicza faba L , J exp Bot , 8, 127-138 (1957)

( 9 ) KAMAE, M : Physiological studies on blooming and podding in soy bean plant (Preliminary re- port), (1) Experimental studies on flower drop- ping and pod shedding, Proc Crop Scz Soc Japan,

21, 1 1 7-1 18 (1952), (in Japanese)

(10) OIZUMI, H , NISHIIRI, K : Effects of shading during the early part of growing period of soy- bean plants on their growth and their nitrogen

and carbohydrate contents, Proc Crop Scz Soc

Japan, 24, 188 (1956), (in Japanese)

(1 1) OIZUMI, H , MIKOSHIBA, H.: On the growth of soybean plants sown between rows of wheat plants, especially on the difference of physi- ological condition of soybean plants before and after the harvest of wheat, Pro6 Crop S n Soc

Japan, 27,3 12-3 14 (1 9 58), (in Japanese). (12) SOPER, M H. R : Field beans in Great Britain,

fizeld Crop Abrtr , 9, 65-70 (1956), (Review Article)

(13) TAMAKI, K , NAKA, J : Physiological studies of the growing process of broad bean plants, I. On the variations of chemical components in various organs of the tops during the growing period,

Tech Bull Fac Agr Kagawa Unzv , 11, 13-18 (1 959), (in Japanese)

(14) TAMAKI, K , NAKA, J : Physiological studies of the growing process of broad bean plants, I1

On the relations between the variations of chemical components in the tops and roots during the growing period, Proc Crop Scz Soc.

Japan, 27, 9 7-98 (1958), (in Japanese)

(1 5) TAMAKI, K , NAKA, J : Physiological studies of the growing process of broad bean plants, IV

Effects of N, P, and K nutrient element on the growth and the chemical components in the various organs. Tech Bull Fac Agr. Kagawa

Unzv, 23, 1-9 (1971).

(16) TORREY, J G.: Effects of light on elogation and branching in pea roots, Plant Phyrzol, 27,

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