The Physiology of Host–parasite Relations: Iv. The Effect of Maleic Hydrazide and Indoleacetic Acid on the Rust Resistance of Khapli and Little Club Wheats

Abstract

1,ittTe C~I~PP (rust reaction type 4 ) and Ichapli (nlst reaction type 1 with race 1 5 N ) wheats were grown in santI culture in I-qt. crocks or %-iri. pots. Ilaily applicatioa~s of ~naleic hydrazide or intloleacctie acid were started 5 days before (18 clays after sowitlg), on the day of, a l~d 5 days after inoculatio~z with stern rnst (Race ZSB) aitd were cunti~lucd fur ahout three weeks, Maleic bydrazide inhibiteel growth and, :it 5 and 10 ing. per pot, Am%-ering. Type 4 pustules tievelopecl 011 KBlapli pfanrs treatctl with 5 and 10 rng, of llaaleic hydrazidc dai!y froin the 5th day hefore ancl from the (lay of inoculation. Endoleacetic a~~c t ( 0 . 5 Ing. per pot from the 10th day after sowing) stimulated growth and fiowerr~iy and slightly illcreased the resistance of Zchapli. l'rcatmerzts stdrted , 5 days after inoculatioo h,td no effect on rust development on Khapli, and none of the trc381nellts aItercd the rust reaction of LiktIe Club. Spores prociuced on plants treated with rraaleic. hydrazide gave nort-tinl rusc reactions on untreated p!arits, 'I'he effect of malcic hyclrrizidc on the plants a 1~1 011 rust developnlerit w,ls not altered 1" t h e si~nultaneous applicntioal of uracil, which reversed the growth inhillition caused by thiouracil. Thionracil inhibited rtist development in the presence of r~inlcic hytlrazide. I-aydrazitle (21) and DDT ( 3 ) .fkT;rnnscript receivcrU March 18, 1957.

Enhancement of brown rust in three varieties of wheat by Mendok treatment

“…As mentioned earlier, enhancement of black and brown rusts has been obtained in wheat with maleic hydrazide through soil application (Joshi 1965(Joshi , 1966Samborski et al 1960;Samborski and Shaw 1957a). Samborski and Shaw (19576) observed that in Khapli wheat maleic hydrazide inhibited the growth and caused increases in dry weight, total soluble matter, sucrose, and free amino compounds, particularly glutamine and glutamate, in the first leaves.…”

“…Many investigators (Joshi 1965;Nair 1958;Richards 1957;Samborski et al 1960;Samborski and Shaw 1957a;Simons 1955) have suggested the application of maleic hydrazide for increasing the severity of rusts in cereals and for rendering resistant plants susceptible to infection. This method may be useful for maintaining rust cultures and for multiplying the inoculum.…”

Metabolism of Indoleacetic Acid in Rust Diseases. I. Factors Influencing Rates of Decarboxylation

“…Although it was suggested (31) that IAA might modify pathways of metabolism, subsequent work (5) indicated that the low C./C, Extension of these ideas to cereal rusts such as stem rust of wheat is difficult because visual growth disturbances are absent. Certain treatments (17,27,31) which may be related to hormonal changes can cause breakdown in resistance of wheat to rust. The data available (29) indicate higher IAA levels in diseased plants but consist of one analysis late in disease development when spore production was well under way.…”

Influence of Hormones on Respiratory Metabolism of Healthy & Rust-Affected Tissues

“…14). Applications of growth regulators alter the degree of susceptibility of wheat to stem rust (16,17).…”