effect of uv

8/19/2019 Effect of UV

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A review on

Effects of UV-B on crop yield

Vinay Kumar Singh

Department of Botany, nstitute of Science

Banaras !indu University, Varanasi, ""#$$%, ndia

A&stract

Ultraviolet-B (UV-B) radiation (280-315 nm) infuences various biological

processes and is strongl absorbed b stratosp!eric o"one (#3). But in recent time

due to o"one depletion t!e irradiance o$ UV-B increased so muc! and it becomes a

ma%or global concern& 'tensive researc!es !as been done in recent ears to no*

UV-B e+ects on crop ield& Bioc!emicall in plants UV-B reacts *it! cellular

components and produces reactive ogen species (,#) lie oides. peroides andsuperoides& /!ese cause oidative stress conseuentl a+ect p!otosnt!etic

pigments i&e& c!lorop!ll and carotenoids. nucleic acids (degrades bacbone.

depurination and deprimidination. dimer $ormation. deamination). proteins

(carbonlation). lipids (peroidation)& lants !ave several en"mes and scavenging

compound to seuester reactive ogen species. t!ese are ant!ocanin. carotenoid

favonoids. p!enol. proline. t!iols. glutat!ione. ascorbic acid. a-tocop!erol. catalase

(/). superoide dismutase (#4) and peroidases (#)etc& /!e damage UV-B

cause in plants t!at are observable are reduced p!otosnt!ates. c!anging pigment

content (so senescence). a+ecting lea$ number. lea$ area. plant !eig!t (s!oot and

root lengt!). biomass distribution. fo*ering and ield& UV-B e+ects get more severein combination *it! ot!er stresses lie !eav metals. salinit. *ater de6cit. nutrien

(micro and macro) de6cit. temperature. air pollutants etc&

ntroduction



un *!ic! is ultimate source o$ energ on t!e planet eart! radiates ras o$

di+erent *avelengt! and $reuencies& olar radiation is radiant (electromagnetic)

energ $rom t!e sun& 7t provides lig!t and !eat $or t!e 'art! and energ $or

p!otosnt!esis& /!is radiant energ is necessar $or t!e metabolism o$ t!eenvironment and its in!abitants& /!e t!ree relevant bands. or ranges. along t!e sol

radiation spectrum are ultraviolet. visible (,). and in$rared& #$ t!e lig!t t!at

reac!es 'art!s sur$ace. in$rared radiation maes up 9:&9; o$ *!ile visible lig!t

provides 92&3;& Ultraviolet radiation maes up %ust over 8; o$ t!e total solar

radiation& 'ac! o$ t!ese bands !as a di+erent impact on t!e environment& <ig!t.

some in$rared. some ultraviolet. and micro*aves. pass t!roug! t!e atmosp!ere and

reac!es t!e 'art!=s sur$ace& >amma ras. -ras. most o$ t!e ultraviolet and some

t!e in$rared are absorbed b t!e atmosp!ere and do not reac! t!e 'art!=s sur$ace&

o t!is 8; o$ ultraviolet is normal t!at reac!es to eart!& /!e o"one laacts lie a giant suns!ade. protecting plants and animals $rom muc! o$ t!e sun=s

!arm$ul ultraviolet radiation& #"one (#3) $orms a laer in t!e stratosp!ere. 15-90 m

above eart! sur$ace& 7$ t!e o"one in t!e atmosp!ere $rom ground level to a !eig!t o

?0 m could be assembled at t!e eart!=s sur$ace. it *ould comprise a laer o$ gas

onl about 3 mm t!ic& UV lig!t is divided into t!ree bands@ UV (100-280 nm). UVB

(280-315 nm). and UV (315-900)& UV is t!e most dangerous. but is mostl

absorbed b ogen and o"one molecules in t!e stratosp!ere and does not reac! t!

eart!=s sur$ace&

/!at=s *!at !appened in t!e 1:A0s and 1:80s& oncerns regarding t!e

o"one laer began in 1:A0 *it! aul rut"en=s stud suggesting t!at nitrogen oidecould act as catalsts to destro o"one& /!en. arold Co!nston suggested t!at

nitrogen oides $rom stratosp!eric supersonic transport aircra$t (suc! as t!e

oncorde) mig!t deplete t!e o"one laer b 3 to 23 percent& Det. ,ic!ard tolars

and ,alp! icerone identi6ed a c!lorine reaction t!at could do t!e same& nd in

1:A9. Eario Eolina and F& !er*ood ,o*land suggested t!at Fs

(c!lorofuorocarbons. certain inert gaseous compounds) could also accumulate in t!

atmosp!ere. releasing c!lorine into t!e stratosp!ere t!at could deplete o"oneG F

*ere *idel used in spra cans. as re$rigerants. and as industrial cleaning and drin

agents& ll o$ t!ese eperts concerns proved prescient in 1:85. *!en Coe Farman.

Brian >ardiner. and Con !anlin publis!ed a paper describing t!e serious decline ino"one over ntarctica. t!e so-called ntarctic o"one !ole&

,educed stratosp!eric o"one leads to increases in sur$ace ultraviolet-B

(UV-B) radiation& UV-B ra is *ell no*n $or t!eir ioni"ing e+ects&



'eferences(

1& rut"en. C& /!e 7nfuence o$ nitrogen oides on t!e atmosp!eric o"one content&

Quart J of the Royal Met Soc 1:A0G :?@320-325&

2& Co!nston & ,eduction o$ stratosp!eric o"one b nitrogen oide catalsts $romsupersonic transport e!aust& Science 1:A1 ug ?G 1A3(3::?)@51A-522&

3& tolarsi ,. icerone ,C& tratosp!eric c!lorine@ a possible sin o$ o"one& Canad

Chem 1:A9G 52@1?10-1?15&

9& Eolina EC. ,o*land F& tratosp!eric sin $or c!lorofuoromet!anes@ c!lorine atom

catalsed destruction o$ o"one& Nature 1:A9G 29:@810-2&

effect of uv

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