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Two rice varieties PR-115 and Super-7 were imposed to water stress and different physiological traits were monitored to evaluate the performance of these varieties under drought. Under water stress condition although the relative water content, osmotic potential, chlorophyll content, photosynthesis rate, carbon discrimination and biomass decreased in both the varieties however, the reduction was more pronounced in Super-7 variety. Oryzanol a trans-ester of ferulic acid functions as antioxidant and it increased along with total phenolic and anthocyanin content in both the varieties under drought stress. However, gallic acid, 4 hydroxy benzoic acid, syringic acid and chlorogenic acid showed differential pattern in both of the varieties under water limiting conditions. Under drought, grain yield was penalized by 17 and 54% in PR-115 and Super-7 varieties, respectively in comparison to watered plants. Super-7 variety showed pronounced electrolyte leakage and MDA enhancement under water stress condition. High non photochemical quenching and reduction in Y(NO) and Y(II) indicated balanced energy management in tolerant PR-115 variety. The studies showed that PR-115 is a drought tolerant variety while Super-7 is drought sensitive in nature.

When a biological system is either accidentally or intentionally exposed to radiation, the energy absorbed triggers a number of successive events including damage to living tissues. Major radiation damage is due to the aqueous free radicals generated by the radiolysis of water. These free radicals act as molecular marauders and in turn damage DNA, mitochondrial membrane, lipid, cellular protein, resulting in cellular dysfunction and mortality. In view of the above mentioned facts an experiment was conducted to study the genotoxic effects of γ radiation and its dose effectiveness. The present experiment was conducted on samples of plasmid pBR322 DNA as the in vitro experimental model devoid of any DNA repair and replication machinery. The samples were exposed to different doses of gamma radiations from 1 to 200 Gy. Exposure of plasmid pBR322 DNA to γ radiation resulted in production of single strand breaks as a result of which, the supercoiled (SC) form was converted to relaxed form (RL). Exposure of radiation, even at very low dose of 1 Gy, exhibited a significant damage to DNA resulting in about 70% SC form and 30% RL form of DNA. At a dose of 10 Gy the SC form was reduced to about 37% and further 5% at a dose of 50 Gy with about 88.5 and 6.5% RL and linear (L) forms of DNA respectively. Thus, the disappearance of supercoiled form of plasmid pBR322 DNA was found to be directly related to radiation dose and exhibited a radiation dose dependent pattern.

Isoetes ×gopalkrishnae hybr. nov., is described, illustrated and compared with possible parent species. Based on morphological characteristics and habitat conditions, this taxon is considered to represent a sterile hybrid between I. coromandelina and I. panchananii. The new hybrid is amphibious and grows on the exposed shore of an artificial pond. It is known only from a single locality on the Vindhya plateau in Uttar Pradesh, India. It can be distinguished from other taxa by a combination of characters including the lack of a scale, the leaf which is terete in transverse section, velum absent to rudimentary, a sporangial wall with internal pigmentation, rugulate megaspores with a smooth equatorial girdle and microspores with densely echinate to short-cristate ornamentation. It is the first Isoetes hybrid reported from the Indian subcontinent.

Nanotechnology has the potential to reinforce the mission toward evergreen revolution by enhancing agricultural productivity with limited inputs. It is emerging as a paradigm shift and evolving as a promising tool to begin a new era of precise farming techniques and therefore may provide a possible solution for crop improvement, even in challenging environments. Employment of engineered nanoparticles (ENPs), whether carbon- or metal-based, may be the future solution to increase crop production for feeding the fast-growing world population. This chapter provides an overview of the current knowledge on the effects of nanoparticles for crop improvement. Overriding influences of different carbon, metal-based and metal oxide nanoparticles on different growth parameters (number of seminal root initiation, root elongation, shoot length, number of seeds, flowers and its quality), ultimately leading to increased plant biomass and yield have been presented. Throughout this chapter, the beneficial role of nanoparticles through enhanced seed germination, increased root and shoot length, fruit and crop yield, and substantial increase in vegetative biomass of seedlings and plants in many crops including maize, wheat, alfalfa, soybean, mustard, mung bean, tomato, potato, lettuce, spinach, onion, peanut, borage, Arabidopsis, cluster bean, and bitter melon is highlighted. The experimental evidences for enhancement of secondary metabolites through nanoparticle treatment under in vivo and in vitro conditions are presented. Although implementation of nanotechnology for agriculture sustainability via enhanced yield, biomass, and secondary metabolite is at juvenile stage, world will witness exceptional and unparalleled prospective of nanoparticles for invigorating agriculture in many ways. It is evident that more investigations are urgently required to know the type of nanoparticle, size, concentration, and mode of application to enable its application on large scale for crop improvement.

The field of plant nanotechnology has recently been up-surged into a new epoch of discovery to dissect the intricate processes and mechanisms for better understanding of plant’s functional biology in response to nanoparticle exposure. This chapter reviews the current scenario of pathways, mechanisms, and patterns of uptake, translocation, accumulation, transformation, and generational transmission of nanoparticles in plants. Experimental data support that symplastic route is the dominant and highly regulated pathway for transporting NPs within plants and facilitated by a vast array of carrier proteins, aquaporins, interconnected ion channels, endocytosed pathway, or novel pores for the entry of nanoparticles. Xylem being the most preferred plant tissue along with phloem and stomatal opening for absorption and transportation of nanoparticles. Engineered and carbon-based nanoparticles have shown different responses for their transport and utilization in different plants. Engineered nanomaterials are translocated and accumulated differentially within stems, leaves, trichomes, petioles, and fruits of different plants. At subcellular locations, engineered nanomaterials are accumulated in cell walls, cytoplasm, seldom plastids, nuclei, and small vesicles. Carbon-based nanomaterials have shown superior prospective for internalization. Uptake, accumulation, and generational transmission of NOM-suspended carbon nanopartcles in rice plants have been reported. Uptake and biodistribution of fullerol was confirmed almost in all plant organs including petioles, leaves, flowers, and fruits in bitter melon. Carbon nanotubes have shown the possibilities for effective penetration into seed coat. Single-walled carbon nanotubes have shown their capability to penetrate chloroplasts and accumulate on thylakoids and stroma in spinach, whereas, multi-walled carbon nanotubes were observed in the seeds and root systems of the developed tomato seedlings. It is certain that not a single transportation mechanism, but a diverse array of multiple mechanisms at physiological, biochemical, and molecular levels are involved for penetration, acquisition, and in planta trafficking of nanoparticles. The goal of this chapter is to put individual experimental efforts back together to unveil the possible enigmas of mechanisms of internalization of nanoparticles, pathways of their movement, and patterns of accumulation and their generational transmission.

The genus Isoetes L. in India is represented by 14species, of which eight species are recognized as being local endemics [confinedto one particular phyto-geographical division (PGD)] while the remaining sixoccur in more than one PGD and are described as endemic to a wider range. Thelocal endemic species are Isoetes dixitei,Isoetes panchganiensis and Isoetessahyadriensis in Western Ghats region; Isoetespantii, Isoetes bilaspurensis, Isoetesreticulata and Isoetes tuberculata inChotanagpur Malwa Vindhya Plateau and Isoetes debii innortheastern India. The wider endemic species are Isoetespanchananii, Isoetes sampathkumaranii,Isoetes rajasthanensis, Isoetesmahadevensis, Isoetes indica andIsoetes coromandelina. Our studies on the patterns ofendemism suggest that the radiation of quillworts advanced from dry lowlandareas to the rainy uplands and mountains. Isoetescoromandelina is the first Indian quillwort to colonize in lowlandsof the coastal zone (Coromandel), from where it spread to different parts of thesub-continent and gave rise to new species. Thus this species is a key Indianspecies which has played an important role in the radiation of quillwort in thecountry and appeared as the connecting link among the quillwort flora of variousPGDs. The centres of diversity for almost all the presently known Indianquillworts species are recognized.

The oomycete, Phytophthora infestans, is one of the most important plant pathogens worldwide. Much of the pathogenic success of P. infestans, the potato late blight agent, relies on its ability to generate large amounts of sporangia from mycelia, which release zoospores that encyst and form infection structures. Until recently, little was known about the molecular basis of oomycete pathogenicity by the avirulence molecules that are perceived by host defenses. To understand the molecular mechanisms interplay in the pathogen and host interactions, knowledge of the genome structure was most important, which is available now after genome sequencing. The mechanism of biotrophic interaction between potato and P. infestans could be determined by understanding the effector biology of the pathogen, which is until now poorly understood. The recent availability of oomycete genome will help in understanding of the signal transduction pathways followed by apoplastic and cytoplasmic effectors for translocation into host cell. Finally based on genomics, novel strategies could be developed for effective management of the crop losses due to the late blight disease.

Nanotechnology has the potential to reinforce the missiontoward ever-green revolution by enhancing agricultural productivity with limited inputs. Zinc plays a vital role in growth hormone production, internode elongation and sexual reproduction by affecting production and shape of pollen and changes in the stigma. Keeping above facts under consideration an experiment was conducted to study the effect of Zincoxide nanoparticles(ZnONPs) on reproductive and biochemical parameters in sunflower. ZnONPs treated and untreated seeds of sunflower were grown in sand culture supplemented with zinc deficient Hoaglandsolution in order to provide representative indication of the impact of ZnONPs on plants under environmentally relevant conditions. Plants treated with ZnONPs exhibited early flowering, improved pollen viability and high starch content in pollens with respect tocontrol. Flowers bloomed first in seeds and plants treated with ZnONPs at a concentration of 250 ppm, followed by 1000 ppm oftreated seeds and untreated sand. The highest pollen viability was observed in treated seeds and treated plant at a concentrationof 500 ppm and the lowest in treated seeds with foliar application at 1000 ppm. Starch content was the highest at 250 ppm in treated seeds and untreated plants and the lowest in treated seeds and treated plants at 500 ppm concentration. This experiment revealed that ZnONPs has exhibited note worthy effect onreproductive and biochemical parameters of sunflower plant at different concentrations and under different modes of application.

Green synthesis emerged as an exciting approach in the field of nanotechnology. Biogenesis of nanosilver is simple, eco-friendly, safe and cost-efficacious and therefore gaining impetus nowadays. An effort has been made to understand the possible induced mechanism for the biosynthesis of silver nanoparticles by exposing a mixture of 1 mM AgNO 3 with aqueous extracts of garlic ( Allium sativum ) and onion ( Allium cepa ) under light and dark conditions. In the synthesis of silver nanoparticles, components of garlic and onion bulb extract served both as capping and reducing agents, whereas the light acted as catalyst. Green synthesized silver nanoparticles were quantified spectrophotometrically at different time intervals. Scanning electron microscopy confirmed that biosynthesized nanoparticles were polydispersed, spherical in shape and under the size range of 100 nm. Light proved to be an stimulating factor in the green synthesis of silver nanoparticles which may vary from species to species.

The oomycete, Phytophthora infestans, is one of the most important plant pathogens worldwide. Much of the pathogenic success of P. infestans, the potato late blight agent, relies on its ability to generate large amounts of sporangia from mycelia, which release zoospores that encyst and form infection structures. Until recently, little was known about the molecular basis of oomycete pathogenicity by the avirulence molecules that are perceived by host defenses. To understand the molecular mechanisms interplay in the pathogen and host interactions, knowledge of the genome structure was most important, which is available now after genome sequencing. The mechanism of biotrophic interaction between potato and P. infestans could be determined by understanding the effector biology of the pathogen, which is until now poorly understood. The recent availability of oomycete genome will help in understanding of the signal transduction pathways followed by apoplastic and cytoplasmic effectors for translocation into host cell. Finally based on genomics, novel strategies could be developed for effective management of the crop losses due to the late blight disease.

Drought is a major stress that dramatically limits plant growth and productivity. Polyethylene glycol (PEG) has been used for osmotically induced water stress studies in plants. The present work was designed to examine the biochemical response in six barley varieties (three tolerant and three sensitive) at different osmotic potential of Polyethylene glycol-6000 (PEG-6000). The results showed at-3.0 bars osmotic potential of PEG-6000 decreased total chlorophyll and an increase in electrolyte leakage and catalase activity was observed in barley leaves.

Agriculture is the backbone of most developing countries and it provides food for humans, directly and indirectly. Agricultural practices are catching public attention globally because climate change, energy and resource constraints, and rapidly growing global population are constantly increasing pressure on food and water resources. The use of nanoparticles in crop sciences is consistently increasing. Several advantageous effects of nanoparticles have been observed on crop plants. Copper (Cu) is an essential nutrient for the growth of plants and plays an important role in the photosynthetic reactions. Copper activates several enzymes, contributes in RNA synthesis and improve the performance of photosystems. But at higher level of Cu, seed germination and plant growth may be adversely affected. In the present study we administered copper oxide nanoparticle in varying concentration to assess the changes in germination percentage, root and shoot length, vigor index and total chlorophyll in soybean. Results showed a significant change in all the above parameters at 200ppm concentration in response to control. Thereafter high concentration of copper oxide nanoparticle proved to be toxic resulting in decrease in plant germination and decrease in vigor index and total chlorophyll.

Mahabaleshwar in Maharashtra, India. They were determined by the authors as belonging to that species on the basis of descriptions and illustrations given by Shende (1945) since the type specimen was not available for comparison. Microspores were acetolysed with acetic anhydride and concentrated sulphuric acid according to the method of Erdtman (1952). Megaspores were studied after treating them with 30% HF for 24 hours to dissolve the perispore and untreated. LM microphotographs were taken in transmitted and refracted light using a Nikon HFX-IIA Optiphot and SEM microphotographs with a JEOL SEM 35C model after coating the dry spores with a thin conductive film of gold palladium about 200 A in thickness, in an ion sputter coater (JFC 1100). SEM studies of microspores and megaspores were conducted at the National Botanical Research Institute, Lucknow. The details of the SEM wall ultrastructure of the spores of I. dixitei are described in the text. The descriptive terms used in the present paper have been taken from the glossaries given by Jackson (1928), Kremp (1965) and Hickey (1966). The mircospores (Fig. 2, A-F) are bilateral-monolete or tetrahedral-trilete, 16-45(33) pm in diameter and their monolete and trilete proximal ridges are thin and high. The spore wall is three layered (described here as perispore, exospore and mesospore). The perispore is echinate. It appears granular under LM, but when scanned under SEM, its surface shows well defined sharply pointed and uniformly distributed "spines" whose broad bases may sometimes coalesce with one another to form intersecting muri. The exospore may be granular or it may show very fine and short muri. The mesospore forms a smooth walled round or oval sac which is firmly attached to the exospore. The megaspores (Fig. 1 A-R; Fig. 3 A-F, Fig. 4 A-H) are dimorphic i.e., of two different sizes: the larger megaspores are pyramidal globose, 440-610(515) pm in diameter. The smaller ones are flattened in the proximal distal plane and are 255-440(360) pm in diameter. As a rule the megaspores show tri-radiate ridges on the proximal side, but in rare specimens the ridges are tetra-radiate (Fig. 4, D). The proximal ridges are straight or sinuous and up to 70 pm high. The equatorial ridge is of variable height: at the junctions with the proximal ridges