Understanding environmental responses of pulse crop species and their wild relatives will play an important role in developing genetic strategies for crop improvement in response to changes in climate. This study examined how cultivated lentil and wild Lens germplasm responded to different light environments, specifically differences in red/far-red ratio (R/FR) and photosynthetically active radiation (PAR). Three genotypes of each the seven Lens species were grown in environmentally controlled growth chambers equipped to provide light treatments consisting of different R/FR ratios and PAR values. Our results showed that overall, days to flower of Lens genotypes were mainly influenced by the R/FR induced light quality change but not by the PAR related light intensity change. The cultivated lentil (L. culinaris) showed consistent, accelerated flowering in response to the low R/FR light environment together with three wild lentil genotypes (L. orientalis IG 72611, L. tomentosus IG 72830, and L. ervoides IG 72815) while most wild lentil genotypes had reduced responses and flowering time was not significantly affected. The longest shoot length, longest internode length, and largest leaflet area were observed under the low R/FR low PAR environment for both cultivated and wild lentils. The distinctly different responses between flowering time and elongation under low R/FR conditions among wild Lens genotypes suggests discrete pathways controlling flowering and elongation, which are both components of shade avoidance responses. The yield and above-ground biomass of Lens genotypes were the highest under high R/FR high PAR conditions, intermediate under low R/FR low PAR conditions, and lowest under high R/FR low PAR light conditions. Three L. lamottei genotypes (IG 110809, IG 110810, and IG 110813) and one L. ervoides genotype (IG 72646) were less sensitive in their time to flower responses while maintaining similar yield, biomass, and harvest index across all three light environments; these are indications of better adaptability toward changes in light environment.

The interaction between plant hormones throughout plant regeneration and development is complex. In the present study, we extended our investigation and disclosed the capacity of de novo shoot organogenesis from cotyledon explants of bottle gourd in relation to plant hormones and ethylene inhibitor. Synergistic effect of kinetin and benzyl adenine (BA) enhanced the shoot regeneration efficiency (80.6%) from cotyledon explants of bottle gourd, compared with BA or kinetin used separately, even in the presence of AgNO 3 . The use of BA or kinetin separately or in synergistic combination led to a characteristic brownish color of the explants at the bud formation stage which was related to ethylene production. In the cotyledon explants cultured on MS medium supplemented with kinetin, the production of ethylene was lower than when BA or the combination of BA and kinetin was used. However, the regeneration capacity was very low and the emergence of shoot buds was delayed. BA promoted ethylene production while the synergistic effect of kinetin and BA decreased ethylene production and played a role in high frequency of regeneration from cotyledon explants of bottle gourd. The physiological relevance of the hormonal interaction in relation to the regulation of ethylene action and effect on regeneration was discussed.

Changes in cytokinin activity in the flag, first, second, and third leaves and in the developing grain of rice (Oryza sativa L.) were studied using the soybean callus bioassay in relation to the movement of photosynthate during different developmental stages. Cytokininlike activity in leaves was highest at the 85th day after transplantation. The flag leaf maintained higher cytokinin activity than other upper leaves. In grains high cytokininlike activity during the 1st week after anthesis is correlated with the grain setting and cell division period. The concentration gradient of cytokininlike substances in the upper parts of the plant was highest in the panicle after anthesis. The data suggest that the developing rice grains attract most of their photoassimilate from their nearest neighbours, the metabolically active flag, first, and second leaves.

In this study, we have investigated the effect ofpolyamines (PA) and silver nitrate (AgNO3) on the high frequency regeneration from cotyledon explants of bottle gourd containing Murashige and Skoog (MS) media supplemented with different kind of Cytokinin alone or in the combination. Synergistic effect of kinetin (1 mg L(-1)) and benzyl adenine (BA) (2 mg L(-1)) itself showed highest shoot regeneration (80.6%) efficiency than BA or Kinetin alone in cotyledon explants of bottle gourd without adding AgNO3 or PAs. We have also observed that PAs and AgNO3 show their sensitivity on the regeneration, which is hormonal dependent. Regenerated shoots were rooted in half strength MS media containing 0.1 mg L(-1) IAA.

Endogenous cytokinin activity was determined in the flowers of Cosmos sulphureus Cav. from bud emergence to full bloom using the soybean callus bioassay. Cytokinin activity was low early in flower development but increased prior to full bloom. In Sephadex LH-20 column chromatography of flower extracts, the cytokinins present co-eluted with zeatin, zeatin riboside and glucoside cytokinin. While the former two predominated prior to full bloom, cytokinin glucoside activity appeared to be at a maximum at full bloom. The possible relevance of these findings is discussed in relation to flower development.

Qualitative and quantitative differences in cytokinin levels of gram seeds were observed during germination of control and 6-benzylaminopurine (BAP; 4.44 x 10 -5 M) treated seeds. Zeatin riboside (ZR), zeatin (Z), dihydrozeatin (DHZ), isopentenyladenosine (iPA) and isopentenyladenine (iP) were determined using high pressure liquid chromatography. In the control seeds the ZR content increased markedly only after 24 h of germination. In BAP treated seeds, the increase in ZR content was stronger than in control seeds and it persisted during further germination. Z content increased during germination in both control and treated seeds. After 48 h of germination iP appeared in control and especially in treated seeds.

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Cytokinin‐like activity in extracts of leaf laminae, petioles, shoots, roots and flowers of young plants of the water hyacinth, Eichhornia crassipes S. was analyzed following Sephadex LH‐20 column chromatography using the soybean callus bioassay. In all plant parts analyzed, two prominent peaks of cytokinin activity having elution volumes similar to zeatin and zeatin riboside were detected. Putative cytokinin gluco‐side‐like activity was detected only in leaves and flowers. The cytokinin complements of the leaves and the roots were qualitatively different. It would appear that cytokinins supplied by the roots are metabolized in the leaves or certain cytokinins are synthesized in the leaves themselves. The possible significance and distribution of cytokinins in different plant parts in relation to roots is discussed.