Photo-temperature response of ramie (Boehmeria nivea (L.) Gaud.) male sterile lines

doi:10.4236/as.2011.22016

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Vol.2, No.2, 111-116 (2011)

doi:10.4236/as.2011.22016

Agricultural Sciences

Photo-temperature response of ramie (Boehmeria nivea

(L.) Gaud.) male sterile lines

Fei-Hu Liu1*, Hai-Quan Huang1,2, Shou-Wen Zhang3, Xue-Ni Liang1

1Plant Improvement and Utilization Laboratory,Yunnan University, Kunming, China;

*Corresponding Aut hor: hnplantbreed@gmail.com

2College of Landscape Architecture, Southwest Forestry University, Kunming, China;

3Department of Ph a rmacy, Jiangxi University of Traditional Chinese Medicine, Nanchang, China;

Received 3 February 2011; revised 2 March 2011; accepted 31 March 2011.

ABSTRACT

Six male sterile lines (MSLs) of ramie (Boehme-

ria nivea (L.) Gaud.) were grown in dark rooms

under the photoperiods of 9.5 h, 11 h or 12.5 h

d–1 in spring and summer seasons (different en-

vironmental temperatures) to test their devel-

opmental response to photoperiod and tempe-

rature. The MSLs showed little difference in ve-

getative growth duration, but different devel-

opment rates in the reproductive growth stage

under the tested conditions. Higher temperature

(grown in summer) mainly accelerated vegeta-

tive growth, while the short photoperiod treat-

ment accelerated the reproductive growth of the

MSLs. Moreover, the short photoperiod treat-

ment combined with higher temperature obvi-

ously accelerated both the vegetative and re-

productive growth of the MSLs. But the effect of

higher temperature decreased, or even disap-

peared along with the photoperiod elongation.

The MSLs were divided into 5 photo-tempera-

ture response types, based on the flower bud-

ding acceleration of short photoperiod and the

approximate temperature response index.

Keywords: Flower Budding Acceleration;

Photoperiod Sensitivity; Ramie (Boehmeria Nivea

(L.) Gaud.); Temperature Response Index

1. INTRODUCTION

Male sterility exists in many plant species [1]. The

discovery of plant male sterility allowed the use of crop

heterosis, resulting in great achievements in crops such

as corn, rice, wheat, rape and many vegetables [1,2].

Ramie, mainly grown in China, the Philippines, Brazil,

India and Viet Nam, is one of the most popular textile

fiber plants. Ramie fabrics are becoming popular all over

the world owing the mode of “back to the nature”, which

is leading the ramie industry into a new development era.

Ramie male sterile plants were found amongst local cu l-

tivars in the 1960’s [3]. Male sterility can also be pro-

duced by chemical induction [4]. Although some pro-

gress has been made in the biochemical and physiologi-

cal traits of ramie male sterile lines [5,6] and in the

utilization of ramie male sterile heterosis [7,8], a lack of

understanding of the photo-temperature responses of

male sterile lines (MSLs) has impeded further advance-

ments in ramie male sterility utilization. Therefore, we

investigated the development of ramie MSLs under dif-

ferent photoperiods and temperatures (grown in different

seasons), with a view to characterizing their response to

photoperiod and temperature. This information will pro-

vide guidance for determining cross combinations, assist

with the breeding of new cultivars and assist with ramie

seed production generally.

2. MATERIALS AND METHOD

The tested ramie male sterile lines ( MSLs) GS13-942,

GSA-2, SS370, GS14-4, GS14-1 and GS15-8, obtained

via chemical induction from a local cultivar (Liang et al.

1998), were planted in 25 × 35 cm pots under normal

management. The MSLs were treated under 9.5, 11 and

12.5 h·d–1 photoperiods of daylight (natural light), re-

spectively in the spring and in the summer, by putting

them into dark rooms in late afternoon and getting out of

dark rooms in the morning, when the plants grew up to

30 cm tall (30 days old in the spring and 15 days old in

the summer). Pot cultured MSLs, grown under the natu-

ral conditions were used as the controls. Five replicate

pots of each line were used for each photoperiod treat-

ment. Dark room treatment terminated once pistillate

flowers had blossomed. Some MSLs had no staminate

flowers, so the opening s of p istillate flowers (stigma em-

ergence) were recorded. Daily outside temperature data

were collected during the period of experiment.

F. H. Liu et al. / Agricultural Sciences 2 (2011) 111-116

112

The developmental acceleration (DA, %) as a result of

a short photoperiod (or a high temperature) treatment

was calculated as [(A – B)/A]  100 [9], wh ere A was the

growth duration under the long photoperiod (i.e. 12.5 h

d–1, in this experiment), or under low temperature (in the

spring, in this experiment) and B the growth duration

under the short photoperiod (i.e. 9.5 h·d–1), or high tem-

perature (in the summer). Similarly, the flower budding

acceleration (FBA, %) of a short photoperiod treatment

was calculated as [(N – M)/N]  100 [10], where N was

the number of days from shoot emergence to flower

budding for the controls, and M represented the number

of days from shoot emergence to flower budding under

the short photoperiod. An approximate temperature re-

sponse index (TRI) was calculated as (L – H)/(Th – Tl)

[10], where L was the number of days from shoot emer-

gence to flower budding under the low temperature con-

ditions (in the spring for this experiment), H was the

number of days from shoot emergence to flower budding

under the high temperature conditions (in the summer),

Th represented the mean temperature during the summer

treatment period, and Tl was the mean temperature dur-

ing the spring treatment period. Statistical analyses were

done with Statistica 5.

3. RESULTS

3.1. Development Rates of the MSLs under

Short Photoperiod in Different Seasons

The vegetative growth stage, the number of days from

shoot emergence to pistillate budding, showed no evi-

dent difference for the spring treatment, but different for

the summer treatment among the tested MSLs (Table 1).

The MSLs had significant differences in their repro-

ducetive growth duration, the number of days from pis-

tillate budding to pistillate flower blooming, both for the

spring or summer treatments. In addition, under the same

short photoperiod condition (9.5 h·d–1), the MSLs had a

much shorter vegetative growth duration in the summer

than in the spring (Table 1, column av erage). Therefor e,

it is important to adjust the development schedule to

meet the parents’ flowering time when the MSLs are

used in cross breeding.

3.2. High Temperature Accelerates the

Development of Ramie MSLs Mainly in

the Vegetative Growth Periods

Under the suitable temperatures for ramie growth and

under a given photoperiod, higher environmental tem-

perature (summer treatment) accelerated the develop-

ment of the MSLs, resulting in a reduction of growth

duration (Ta bl e 2). This confirmed the sensitivity of the

MSLs to temperature. The development accelerations in

the summer indicated that the high temperature in-

creased the development rate more for the vegetative

growth stage than for the reproductive growth stage

(Table 2). Here the period from shoot emergence (SE) to

pistillate budding (PB) is the veg etative growth duration,

while the period from pistillate budding (PB) to pistillate

flower blooming (PFB) is the reproductive growth dura-

tion.

Among the MSLs, GS13-942 and GS14-1 were highly

sensitive to season change (maybe mainly the effect of

temperature), showing the approximate temperature re-

Table 1. Development duration of ramie MSLs under 9.5 h·d–1 photoperiod.

Developmental duration of MSLs (d)†

Growth

period Seasons Daily mean

temperature(˚C) GS13-942 GSA-2 GS15-8SS370 GS14-4GS14-1

Aver-

age‡ P-value

Spring 23.0 39a 39a 39a 39a 40a 39a 39a 0.000

SE-PB Summer 29.4 18c 20b 22a 22a 23a 20b 21b 0.000

Spring 24.4 22a 22a 17b 18b 21a 17b 19a 0.062

PB-PFB Summer 30.8 20a 17b 17b 16b 17b 14c 17a 0.062

SE—shoot emergence; PB—pistillate budding; PFB—pistillate flower blooming; †Followed by the same letter are not significantly different at P = 0.05 among

the MSLs by LSD test; ‡Comparison of summer vs spring within each growth period at P = 0.05 by T-test.

Table 2. Effect of season (temperature) on the development of MSLs under 9.5 h·d–1 photoperiod.

Duration (d  SD) Daily mean temp in the period (°C)

Growth period Spring Summer Spring Summer

DA of high

temperature (%)

SE-PB 39  0.4 21  1.8 23 29 47

SE-PFB 59  3.5 38  3.1 24 30 35

PB-PFB 19  2.4 17  1.9 24 31 12

SE—Shoot emergence; PB—Pistillate budding; PFB—Pistillate flo wer blooming; DA—Devel opmental acceleration.

F. H. Liu et al. / Agricultural Sciences 2 (2011) 111-116

113

sponse indices (TRI) over 3. GS15-8 and SS370 were

not very sensitive to season change, the TRIs were 2.5 or

below. GSA-2 and GS14-4 showed moderate sensitivity

to season change (Table 3).

3.3. Short Photoperiod Accelerates the

Development of Ramie MSLs Mainly in

the Reproductive Growth Periods

The influences of photoperiods on the development of

MSLs were studied by growing the MSLs under differ-

ent photoperiods. It was found that shorter photoperiod

evidently accelerated the development rates of the MSLs,

especially promoting the reproductive development and

shortening the reproductive growth duration (Table 4).

Under photoperiods of 9.5 - 12.5 h·d–1, the development

promotion effect (DA%) increased as the photoperiod

shortened. Besides, the development acceleration of a

short photoperiod was much greater in the high tem-

perature season (summer) than in the low temperature

season (spring) (Table 4). The results testified a quite

high sensitivity to photoperiod of the MSLs and they

developed more quickly under shorter photoperiod.

In the summer, the MSLs grew 37-59 days from shoot

emergence to pistillate budding under the natural condi-

tions (the controls), while under the short photoperiods

(9.5 - 11 h·d–1), the MSLs grew only 18 - 23 days before

pistillate budding. The MSLs shortened their basic

vegetative growth period and started their reproductive

growth earlier under the short photoperiod. Flower bud-

ding acceleration under a short photoperiod can be used

to scale the photoperiod sensitivity of a plant. The

greater the acceleration, the higher the photoperiod sen-

sitivity was. If the acceleration of 60% is taken as a cri-

terion for dividing the photoperiod sensitivity of the

MSLs, then GS13-942 and SS37 0 are highly sensitive to

the photoperiod, and the others are less sensitive (Table

5).

3.4. Short Photoperiod in Conjunction with

High Temperature Accelerates the

Development of Ramie MSLs in the

Whole Growth Period

As mentioned above, high temperature (summer treat-

ment) mainly accelerated development in the vegetative

growth stage, while the short photoperiod mainly pro-

moted development in the reproductive growth stage.

Consequently, it is expected that a short photoperiod in

conjunction with a high temperature would accelerate

the MSLs development in the whole growth period, re-

sulting in a reduction of the whole g rowth duratio n. This

was verified by the results in Table 6.

The MSLs were quite highly sensitive to both tem-

perature and photoperiod. They developed faster and had

a shorter whole growth period under the short photope-

riod and high temperature conditions (in the summer),

and vice versa under the long photoperiod and low tem-

perature (in the spring). Therefore, it may assist of hy-

bridization by treating the ramie MSLs with a short

Table 3. Approximate temperature response indices (TRI) of the MSLs under different photoperiods.

TRI under photoper iods

Male sterile line 9.5 h·d–1 11 h·d–1 12.5 h·d–1

Mean

TRI Temperature sen-

sitivity

GS13-942 3.3 3.2 3.2 3.2 High

GS14-1 3.0 3.2 3.1 3.1 High

GSA-2 3.0 2.9 2.9 2.9 Moderate

GS14-4 2.7 2.8 2.9 2.8 Moderate

SS370 2.7 2.5 2.4 2.5 Low

GS15-8 2.7 2.5 2.1 2.4 Low

Table 4. Effect of photoperiods on ramie MSLs development.

Treated in the spring Treated in the summer

Developmental duration (d  SD) DA of short photoperiod

(%)† Developmental duration (d  SD) DA of short photoperiod

(%)†

Growth

period 9.5 h·d–1 11 h·d–1 12.5 h·d–1 9.5 h·d–1 11 h·d–1 9.5 h·d–1 11 h·d–1 12.5 h·d–1 9.5 h·d–1 11 h·d–1

SE-PB 39  0.4 39  1.041  2.3 3.7 3.7 21  1.821  1.823  2 .1 9.3 8.7

SE-PFB 59  3.5 60  2. 668  2.8 13.3 12.1 38  3.146  2.654  3.0 29.2 14.9

PB-PFB 19  2.4 20  2.027  1.8 27.8 24.7 17  1.925  2.032  2.5 45.9 22.1

†Compared with 12.5 h·d-1 photoperiod; DA—Developmental acceleration; SE—Shoot emergence; PB—Pistillate budding; PFB—Pistillate flower

blooming.

F. H. Liu et al. / Agricultural Sciences 2 (2011) 111-116

114

Table 5. Photoperiod sensitivities and flower budding acceleration (FBA) of ramie MSLs under short photoperiods (treated in

the summer).

Under 9.5 h·d–1

photoperiod Under 11 h·d–1

photoperiod

Male sterile

lines Days from SE to PB

for controls† Days from

SE to PB† FBA(%) Days from

SE to PB† FBA(%)

Mean FBA

(%) Photoperiod

sensitivity

GS13-942 51  3.0 18  1.0 64.7 20  0.6 60.8 62.8 High

SS370 59  3.5 22  0.4 62.7 22  0.4 62.7 62.7 High

GS15-8 45  2.8 22  0.5 51.1 21  0.9 53.3 52.2 Low

GS14-1 38  2.2 20  0.9 47.7 19  1.0 52.6 50.2 Low

GSA-2 37  2.5 20  0.6 45.9 21  0.6 43.2 44.6 Low

GS14-4 37  2.4 23  1.2 37.8 21  0.5 43.2 40.5 Low

SE—shoot eme rgence; PB—pi stil late budding; †Mea n  SD

Table 6. Combined effects of high temperature and short photoperiod on development of ramie MSLs.

Growth duration (d  SD) DA of Th under photoperiods (%  SD)

Growth

period Under SD and Th Under LD and Tl

DA of SD

and Th (%) 9.5 h·d–1 11 h·d–1 12.5 h·d–1

SE-PB 21  1.8 41  2.3 49 47  3.2 46  2.3 43  3.0

SE-PFB 38  3.1 68  2.8 44 35  2.1 23  2.4 21  2.5

PB-PFB 17  1.9 27  1.8 37 12  1.2 – 21  1.5 – 17  1.4

DA—developmental acceleration; SD—short daylight (9.5 h d–1 photoperiod); LD—long daylight (12.5 h d–1); Th—high temperature (i n the sum-

mer); Tl—low temperature (in the spring); SE —shoot emergence; PB—pistillate b ud ding; PFB—pi s ti ll ate flower blooming.

photoperiod in different seasons to facilitate cross com-

binations and avoid of an unexpected pollination. Fur-

thermore, the acceleration effect of a high temperature

on ramie MSLs could be decreased, or even cleared

away by elongated photoperiod (Table 6).

3.5. Types of Photo-Temperature Sensitivity

of Ramie MSLs

MSLs are important parents for ramie heterosis utili-

zation, their characteristics of photo-temperature re-

sponse are therefore important for mating needed cross

combinations. The response type of a plant to photo-

temperature can be determined by the photoperiod and

temperature sensitivities, and the basic vegetative gr-

owth period. Owing to different response to photoperiod

and temperature, the 6 ramie MSLs in this experiment

might be classified into 5 types based on the flower bud-

ding accelerations of short photoperiod and the appro-

ximate temperature response indices (Table 7).

4. DISCUSSION

The photo-temperature responses of a crop are of im-

portance both in theory and practice. Understanding

these characteristics is helpful, on the one hand, to de-

termine the suitable cultivation areas of the crop for get-

ting high and stable yield. On the other hand, it is good

to adjust the flowering time of the cross parents for suc-

cessful hybridization, or to stage the cross time of dif-

ferent combinations avoiding of an unexpected pollina-

tion.

Ramie cultivars are usually a short-day crop. It has

been determined that short photoperiod treatment pro-

motes the development of the ordinary ramie varieties

and makes them flower earlier [3,11]. It takes fewer days

of short photoperiod to induce ramie flowering under the

high temperature seasons (in the summer or early au-

tumn) than under the low temperature seasons (in the

spring or early summer) [3]. While different responses of

wild species in genus Boehmeria to short photoperiod

were observed by Pan et al. [12]. However, it is still nec-

essary to have a systematic study of the photo-tempera-

ture responses for ramie varieties, especially for ramie

MSLs. In our experiment, we confirmed that the tested

ramie MSLs are sensitive to the temperature and photo-

period by growing the MSLs under different photo-

periods and different season (temperature) conditions.

The short photoperiod and high temperature (in the

summer) can evidently decrease the growth period and

make the MSLs flower earlier. But the acceleration ef-

fect of high temperature can be minimized, or even

cleared away by long photoperiod.

The effects of photoperiod and temperature on ramie

development are complex. In this experiment, due to

lack of the staminate flowers in some of the tested MSLs,

the female reproductive organs were recorded as a coin

F. H. Liu et al. / Agricultural Sciences 2 (2011) 111-116

115

Table 7. Response type of ramie MSLs to photoperiod-temperature.

Type Re spon se s ensit ivity to photope-

riod-temperature FBA of short photo-

period† Temperature response index‡ Representative MSLs

1 High sensitivity to both photoperiod and

temperature ≥ 60% > 3.0 GS13-942

2 Sensitivity high to photoperiod and low

to temperature ≥ 60% ≤ 2.5 SS370

3 Sensitivity low to photoperiod and high

to temperature < 60% > 3.0 GS14-1

4 Sensitivity low to photoperiod and mod-

erate to temperature < 60% 2.6～3.0 GS14-4, GSA-2

5 Low sensitivity to both photoperiod and

temperature < 60% ≤ 2.5 GS15-8

†Represents the photoperiod sensitivity; ‡Represents the tem perature sensitivity; FBA—Flower budding acceleration.

cident indicator for observation, but the effects of temon

the development of the male reproductive organs of the

MSLs were neglected. In fact, in some experiments it

was observed that the environmental temperature could

change the pollen fertility of some rape male sterile lines

[13,14]. This was considered as a result of th e combined

effect of the environmental temperature and the nutrition

status in the MSLs [14]. In our experiment we also

found a yearly difference in the development of the sta-

minate flower buds in some MSL, and the bigger and

higher plants had somehow better developed staminate

flower buds. Are there interactive effects of the envi-

ronmental temperature and the nutrition status on the

expression of fertility in the ramie MSLs, and on the

temperature-sensitive response? This is a new problem

to approach. Besides temperature and photoperiod, it is

worthwhile to investigate the effects of changes in sun-

light intensity, wavelength and humidity from spring to

summer on the development of ramie MSLs.

5. CONCLUSIONS

The conclusion was derived by summarizing the de-

velopmental response to photoperiod and temperature of

six male sterile lines (MSLs) of ramie in the study. The

MSLs showed different development rates in the repro-

ductive growth stage under the conditions of higher

temperature and short photoperiod, but a stable vegeta-

tive growth duration. On the other hand, higher tem-

perature accelerated vegetative growth, while the short

photoperiod treatment accelerated the reproductive gr-

owth of the MSLs. The short photoperiod treatment

combined with higher temperature obviously accelerated

both the vegetative and reproductive growth of the MSLs .

But the effect of higher temperature decreased, or even

disappeared along with the photoperiod elongation. Five

photo-temperature response types were constituted based

on the flower budding acceleration of short photoperiod

and the approximate temperature response index of the

MSLs. The results would provide guidance for deter-

mining cross combinations, assist with the breeding of

new cultivars and assist with ramie seed production.

6. ACKNOWLEDGEMENTS

The authors are grateful to the National Natural Science Foundation

of China (Project No 30360058, Project No 30971825) for financial

support to this study.

REFERENCES

[1] Kaul, M.L.H. (1988) Male sterility in higher plants.

Springer - Verlag Berlin Heidel be rg, New York, 221-232.

[2] Qin, T.C. (1993) Crop breeding by using male sterility.

Chinese Agricultural Press, Beijing.

[3] Li, Z.D. (1989) Ramie physiology, bio-chemistry, genet-

ics and breeding. Chinese Agricultural Press, Beijing,

158-167.

[4] Liang, X.N., Zhang, S.W. and Xiao., D.X. (1998) Studies

on ramie parthenogenesis and pure line creation. Agri-

cultural Modernization Research, 19, 91-94.

[5] Liu, F.H. and Liang, X.N. (2000) Preliminary study on

biochemical and physiological traits of ramie ma le sterile

lines. China’s Fiber Crops, 22, 16-20.

[6] Song, J., Zhang, Z.H. and Pan, G.T. (2007) Physiological

and biochemical characteristics in ramie male sterile

lines. Journal of Tropical and Subtropical Botany, 15,

423-428.

[7] Zhang, Z.H., Wei, G., Xu, J.J., Zhao, S.Y., Yang, Y. and

Qiu, Y.B. (2003) Report on breeding of a new hybrid

ramie combination ‘Chuanzhu 8’ with good quality and

high yield. China's Fiber and Products, 25, 168-171.

[8] Zhang, Z.H., Wei, G., Yang, Y. and Shu, Z.X. (2005)

Breeding and utilization of ramie male sterility line

‘C26’”. Plant Fibers and Products, 27, 109-112.

[9] Diao, C.Q., (1994) Cultivation of field crops (Southern

version). Chinese Agricultural Press, Beijing, 47-57.

[10] Deng, L.Q. (1987) Study on photo-temperature responses

of kenaf varieties. Scientia A gricultura Sinica, 20, 56-62.

[11] Li, Z.D. (1980) The theory and techniques of fiber crops.

Shanghai Science and Technology Press, Shanghai,

99-110.

[12] Pan, Q.H., Lai, Z.J. and Ouyang, A.P. (2005) Preliminary

study on the day-length and temperature characteristics

of wild-type ramie. China's Fiber and Products, 27,

286-291.

[13] Yang, G.S. and Fu, T.D. (1987) Effect of environments on

F. H. Liu et al. / Agricultural Sciences 2 (2011) 111-116

116

rape cytoplasmic male sterile lines. China’s Oil Crops, 3,

15-19.

[14] Li, J.N., Tang, Z.L. and Chen, L. (1995) Effects of tem-

perature on the fertility change stage and critical pa-

rameters of rape male sterile line with Polima cytoplasm.

Journal of Southwest Agricultural University, 17, 391-

394.