A tool used for hybrid seed production in agricultural and horticultural crops.

2.  The chemicals that induce the male sterility in
plants are called Gametocides.
 This terminology was introduced by Eaton, who
demonstrated the potential of producing Gossypium
hirsutum hybrids using FW-450.
 Also termed as Chemical Hybridizing Agents, Male
sterilants, Pollen suppressants, Pollenicides,
Androcides,etc.,

3.  Induction of male but not female sterility
 Complete inhibition of pollen development
 Independent from environmental conditions
 Independent from genotypic differences
 Wide flexibility of rate and time of application

4.  Absence of phyto-toxicity/ adverse effects
 Non mutagenic
 Environmental safety
 Minimum side effects
 Cost effectiveness

5.  Disruption of meiosis lending of arrest of anther
development and degeneration of pollen mother
cells or curly microspores.
 Disruption of exine formation resulting in thin
walled, irregular and non viable microspores.
 Decrese of starch deposition and appearance of
abnormal vacuoles in the micospores making
them non-viable.

6.  Persistence and abnormal growth of tapetal
layers.
 Indehiscence or delayed dehiscence of
normally developed anthers with viable pollen.
 Non-germination of pollen on stigma or
cessation of elongation of pollen tube resulting
in non-fertilization.

7.  Treatment at panicle initiation stage (pre
meiotic) affects normal development of anthers
and PMCs.
 Treatment at bolting stage (meiotic phase ) and
flowering stage (post-meiotic ) disturbs normal
development and functioning of microspores.

8. CHA Chemical formulation Crops
Arsenicals Zinc methyl arsenate,Sodium methyl
arsenate
Rice, ( 5 days before
heading ),Oilseed rape
Dalapon Sodium 2,2- dichloro propionate Cotton,Pearl millet, Wheat,
Linseed,Sesame,Onion,
Capsicum
DPX 3778 3-(p-chlorophenyl)-6-methoxy -3-
triazine-2,4(1H,3H) dione
Maize, Wheat &
Triticale(late tillering+late
boot stages)
Ethepon 2-chloroethyl phosphonic acid, Wheat, Barley , Rice, Oats,
Triticale, Cucumber
FW 450(Mendok) Sodium α,β-dichloro isobutyrate Capsium, Cotton, Pearl
millet, Sesame, Sunflower,
Tomato

9. CHA Chemical formulation Crops
OMT L-O-Methyl threonine Cotton
MH 1,2-dichloropyridazine-3,6-dione Maize,Wheat,Capsicum,Cotton,
Oats,Sorghum,Onion,Okra – Early
microsporogenesis
GA Gibberellic acid Maize, Barley,Wheat,Rice – 1 to 3
days prior to onset of meiosis.
Onion, Oats, Sunflower.,Okra,
6 BAP Benzyl amino purine Onion

10. Proper environmental conditions:
 No rain during CHA application
 Adequate sunshine and absence of strong winds
 Rice – ideal condition : 26-28˚C, 80% RH

11. Synchronisation:
 Flowering of male and female parents
 Achieved by varied sowing dates

12.  Application of CHA at precise stage
 GA3 spray to promote stigma exertion.
 Supplementary pollination to maximise seed set
 2 sprays of CHA @ lower concentration is better
than single application of same dose, as the former
induces more uniform male sterility
 Care not to spray the pollinator rows

13.  Any line can be used as female parent
 Choice of parents is flexible
 Rapid method of developing male sterile line
 No need of maintaining A, B, & R lines
 Hybrid seed production is based on only 2 line system
 Maintanence of parental line is possible by self pollination
 CHA based F2 hybrids are fully fertile as compared to few
sterile hybrids in case of CMS or GMS.

14.  Expression and duration of CHA is stage specific
 Sensitive to environmental conditions
 Incomplete male sterility produce selfed seeds
 Many CHAs are toxic to plants and animals
 Possess carryover residual effects in F1 seeds
 Affect human health

15.  Singhal.N.C., Hybrid Seed Production in Field
Crops Principles and Practices,second edition,
Kalyani publishers,New Delhi
 http://www.arccjournals.com/uploads/articles/ar262
004.pdf
 https://link.springer.com/chapter/10.1007/978-3-
642-83139-3_4