Fruit Development and Structure in Some Indian Bamboos

Fruit structure and development of seven species belonging tofive genera of Indian bamboos are described. The fruit in fourspecies is a caryopsis typical of the family Poaceae. The ovuleis bitegmic; the outer surface of the cells of nucellar epidermisbecomes cutinized and forms the seed coat. Three species beara fleshy fruit with a unitegmic ovule. In a mature fruit theendosperm is either completely absorbed by the embryo or ispresent only in small quantity. The developing embryo comesin direct contact with the fruit wall due to the disintegrationof the nucellus and integument. The embryo is covered by a thickbrown mat from the disorganized cells of the inner layers ofthe fruit wall. Poaceae, Bambusoideae, Bambusa, Dendrocalamus, Melocalamus, Ochlandra, Pseudostachyum (fleshy fruits), fruit wall     

Induction of flowering by cytokinins in a short-day plant, Lemna paucicostata

Lemna paucicostata, normally a short-day plant, can be inducedto flower under long-day conditions by providing a cytokininin a medium containing a high level of ferric citrate (5 x 10^–4M).Interestingly, when a cytokinin and EDDHA are present togetherin the medium, flowering is induced even at low levels of iron(10^–5 and 5 x 10^–5M ferric citrate). However, inthe absence of a cytokinin, flowering takes place only undershort days. (Received September 30, 1968; )     

Apomixis and Polyembryony in the Guggul Plant, Commiphora wightii

The present report is a part of our study on the reproductivebiology of a traditional Indian medicinal plant,Commiphora wightii,a source of guggul steroids. Field examination showed a predominantlylarge number of isolated and groups of female individuals. Onlyone andromonoecious and two exclusively male plants were recorded.Female plants set seed irrespective of the presence or absenceof pollen. Hand-pollination experiments and embryological studieshave confirmed the occurrence of non-pseudogamous apomixis,nucellar polyembryony and autonomous endosperm formation forthe first time in this plant, which is presently threatenedby over-exploitation. Commiphora wightii ; autonomous endosperm; guggul; medicinal plant; non-pseudogamous apomixis; nucellar polyembryony     

Optimal Control of Gas Exchange during Drought: Empirical Evidence

The optimal regulation model by Mäkelä, Berningerand Hari (Annals of Botany 77: 461–467, 1996) was appliedto data for photosynthesis and transpiration of Scots pine duringa 22-d drought period. There was a clear decrease in photosynthesisand transpiration during that period. The agreement betweenmodel and photosynthesis data was good. The residuals of photosynthesiswere not systematic with respect to temperature, irradianceor water vapour deficit. However, the model initially overestimatedtranspiration by 50%, although there was a clear linear relationshipbetween measured and estimated values. The results suggest thatthere was no decrease in photosynthetic capacity during theperiod, but a decrease in stomatal conductance was responsiblefor the changes in photosynthesis and transpiration. The observationsare similar to results in the literature. Transpiration; photosynthesis; stomatal conductance; drought; Pinus sylvestris     

Fungal fruiting bodies from Lower Tertiary sediments of Sirmaur district, Himachal Pradesh, India

Fungal fruiting bodies ignored in earlier palynological investigations of the Subathu and Dagshai Formations have been studied from sediments exposed in the Dadahu Jamtah area, Sirmaur district, Himachal Pradesh. Taxa belonging to the genera Notothyrites, Asterothyrites, Parmathyrites, Phragmothyriles and Microthyriacites have been identified. These fossils are comparable with taxa reported from many Early Tertiary assemblages from different parts of the country and indicate a warm and humid climate.     

Morphology and Physiology of Lyngbya nigra with Reference to Copper Toxicity

The effect of copper sulphate on morphology and physiology of Lyngbya nigra has been studied. The growth was inhibited in all treatments (0.4 to 80.0 μM) of copper sulphate. There were no apparent morphological changes up to 0.8 μM and during the first two days of treatment even in the higher concentrations of copper sulphate. In concentrations above 0.8 μM the first symptom of toxicity was the formation of separation discs in large numbers. The trichomes contracted longitudinally and the cells became swollen and constricted at the cross walls. The cells also became yellowish due to loss of photosynthetic pigments. Finally, in 4 μM and above, vacuoles appeared in large number indicating the moribund state of the cells. Copper sulphate increased respiration at 2 μM, and optimum effect was observed in 8 μM after 96 h. Inhibition of photosynthesis was detectable in 0.8 μM, and 100% inhibition took place in 8 μM after 96 h. In higher concentrations the effect was immediate, and a conspicuous inhibition of photosynthesis could be observed within 10 min. The copper content of the alga increased with increased concentration of copper sulphate while potassium content decreased. With rise in outside concentrations of copper, there was a comparatively great increase of absorption in 2 and 4 μM, while further increases were gradually less. The observations indicate that changes in the physiological activity of the alga under treatment are closely interlinked with marked changes in morphology.     

Embryogenesis and Differentiation in Nigella sativa Leaf Callus in vitro

Embryogenesis occurred in Nigella sativa L. (Fam. Ranunculaceae) leaf callus tissue when coconut milk was replaced from the Murashige and Skoog's (MS) medium by casein hydrolysate. On MS + IAA (0.5 mg/l) + casein hydrolysate (100 and 500 mg/l) medium, tissue gained a capacity of growing embryoids for a pro-longed culture period. At a concentration of 1000 mg/l casein hydrolysate suppressed the differentiating capacity after the fifth subculture. 2.4-D and kinetin had inhibitory effects on morphogenesis. Histology of the differentiated tissue revealed that the origin of roots, shoot buds and leaves were from groups of meristematic cells whereas embryoids were initiated by the repeated division of a single cell.