N. Sankhla

Thidiazuron-induced in vitro shoot formation from roots of intact seedlings of Albizzia julibrissin

Seedlings of silktree (Albizzia julibrissin Durrazz.) were grown in vitro on MS-media containing B5 vitamins, 3% sucrose, 0.25% phytagel and various concentrations (0.1–10 μM) of thidiazuron (TDZ). Addition of TDZ to the culture medium greatly reduced shoot and root elongation but did not influence shoot production from the cotyledonary node or apex. Within 8–10 days the seedling roots split open, formed large masses of callus, and developed green patches which eventually grew into normal shoots while still within the culture medium containing TDZ at 0.1–1.0 μM. Such callus and shoot formation did not occur in control cultures lacking TDZ. At higher TDZ concentrations (2.5–10 μM), the green patches formed in the callus did not further develop into shoots. Addition of other cytokinins (kinetin, benzylaminopurine, zeatin) to the culture medium also induced some shoot formation from the roots, but higher concentrations than TDZ were required to induce regeneration. Isopentenyladenine failed to induced shoot formation. Following excision and transfer to MS media with or without 4.9 μM IBA, the shoots induced by kinetin or benzylaminopurine rooted 4–7 days earlier than those induced by TDZ, but all excised shoots developed into normal rooted plantlets within 3 weeks.

Effect of paclobutrazol on the development of iron chlorosis in soybeans

Abstract Iron‐efficient (A7) and ‐inefficient (T203) soybean cultivars were grown in nutrient solution culture both with and without the plant growth regulator paclobutrazol at low levels of Fe. Paclobutrazol affected root morphology, greatly reduced shoot growth, and delayed the onset of chlorosis in the penultimate leaf of both cultivars by several days at all Fe levels as compared to untreated controls. The chemical delayed, but did not hinder, the iron stress response mechanism (proton and reductant extrusion). Paclobutrazol did not delay the onset of chlorosis by mobilizing Fe to the leaves because foliar Fe content in paclobutrazol treated plants was similar to that of untreated ones. These results suggest that paclobutrazol may be a useful tool in studying the interactions between growth, chlorophyll synthesis, the development of Fe chlorosis, and the Fe stress response mechanism.

Abscisin II-kinetin antagonism in growth ofIpomea cotyledonary callus

Die rund l i chen P l g t t c h e n wurden zuers t von OOLDIN [5] in e inem W e M V W i r t gefnnden, wobei i hnen abe t keine besondere A u f m e r k s a m k e i t gewidmet wurde . D a n k der Gefgll igkeit yon He r rn Dr. Z. PoLs (Prag) k o n n t e n wir anch den t yp i s chen yon H O L ~ S [3] beschr iebenen Sta ture des W e M V anschaf fen . Bet der l i ch tmikroskop i schen Durch s ich t der m i t d iesem Virus inf iz ier ten T a b a k b l g t t e r k o n n t e n wir ebenfalls die rund l i chen PlXt tchen anff inden, die der F o r m u n d S t r u k t u r nach unse ren P l g t t c h e n ghneln . t i sch: W/ ih rend des P a c h y t g n s u n d des Diplot~ins l i nden sich in der H a u p t s a c h e 80 s -Par t ike l ; w&hrend des Dip lo tgns u n d der Diakinese wurden p rak t i s ch keine P o l y s o m e n gefunden . t n der Me taphase t r i t t s o d a n n eine V e r m e h r u n g der Polys o m e n F r a k t i o n e n auf, die i m T e t r a d e n S t a d i n m ein M a x i m u m erreicht. Somi t is t die Meiose gekoppel t m i t ether E l imin i e rung des po lysomalen Mater ia ls der diploiden Pol lenmut terze l le . Die

Morphactin-gibberellin interaction in lettuce seed germination and seedling growth@@@Interakce morfaktinu a gibberelinu při klíčení a růstu klíčních rostlin salátu@@@Взаимодействие морфактина с гибберелином при прорастании семян и росте проростков салата

Morphactin-butylester (a flourene-9-carboxylic acid derivative) inhibited seed germination of two strains of lettuce. Morphactin induced inhibition of germination could be partially or wholly reversed by simultaneous addition of gibberellic acid. However, gibberellic acid played very little part in reversing the inhibitory effect of morphactin on seedling growth. It is concluded that gibberellin can not reverse all the growth effects induced by morphactin.AbstractButylester morfaktinu (derivát fluoren-9-karboxylové kyseliny) inhibuje klíčení semen dvou odrůd salátu. Inhibice klíčemí indukována morfaktinem může být zmírněna až zrušena současným přidáním kyseliny giberelové. Inhibice růstu klíčních rostlin způsobena morfaktinem je však kyselinou giberelovou ovlivňována jen velmi málo. Giberelin tudíž interaguje s morfaktinem jen v některých případech.AbstractБутиловый эфир морфактина (производное флюорен-9-карбоксиловой кислоты) подавляет прорастание семян двух сортов салата. Ингибиция прорастания семян вызваная морфактином уменьшается или полностью устраняется одновременным применением гибберелловой кислоты. Подавление роста проростков вызваное действием морфактина однако одновременным применением гибберелина почти не изменяется. Следовательно гибберелин влияет на действие морфактина не во всех случаях.

Influence of 2-(3,4 dichlorophenoxy)-triethylamine on photosynthesis of Phaseolus vulgaris L.

The effect of foliar sprays of the growth regulator 2-(3,4 dichlorophenoxy)-triethylamine (DCPTA) on net photosynthesis (Pn) by intact bean plants depended upon concentration and the stage of development of the leaves. A single foliar spray of 2.0 mM DCPTA reduced Pn when applied to young expanding leaves but had little effect on fully expanded leaves. Lower DCPTA concentrations (0.2 to 0.8 mM) had no effect on Pn, unless applied more than once which resulted in reduced Pn. The DCPTA-induced inhibition of Pn was associated with chlorosis and aberrations in chloroplast ultrastructure. DCPTA did not affect stomatal resistance. When applied to detached leaf disks in the dark, DCPTA retarded the normal loss of chlorophyll suggesting that DCPTA may have anti-seneseent properties.

Effect of 2-(3,4-Dichlorophenoxy)-Triethylamine on Betacyanin Efflux from Beet Root Tissue

Summary 2-(3,4-dichlorophenoxy)-triethylamine (DCPTA) increased betacyanin efflux from beet root discs possibly by destabilizing the cell membrane. Alcohol and DCPTA act additively in influencing solute efflux. Polyamines, which stabilize the membrane, not only arrested the efflux of betacyanin when used alone, but also counteracted the effect of DCPTA. Kinetic analysis of the data suggests that DCPT A and spermine bind at different sites on the plasmalemma.