Sangeeta Khetarpal

Multiple shoot induction by benzyladenine and complete plant regeneration from seed explants of chickpea (Cicer arietinum L.)

The efficacy of benzyladenine (BA) to induce multiple shoots from seed explants of chickpea (Cicer arietinum L.) was assessed. Shoot differentiation was influenced by the type of seed explant, genotype and concentration of BA. Orientation of the explant also strongly influenced the shoot regeneration response. The optimum BA concentration for shoot/shoot bud regeneration was genotype dependent. Two types of BA-induced response were observed: (1) at less than 7.5 gm BA, direct shoot differentiation (2 to 4-cm-long shoots) was observed within 30 days; (2) at higher BA concentrations (75–100 μm), shoot/shoot bud differentiation was achieved in 45–90 days. A high BA concentration inhibited subsequent rooting of shoots. Roots, however, could be easily induced on shoots derived from <12.5 μm BA. Following transfer to soil, 80% of the regenerants developed into morphologically normal and fertile plants.

Evaluating the efficacy of cyanobacterial formulations and biofilmed inoculants for leguminous crops

Our investigation was aimed towards evaluating the agronomic potential of biofilmed preparations (developed using Anabaena/Trichoderma as matrices with different agriculturally useful bacteria/fungi as partners) and selected cyanobacterial strains (Anabaena laxa (T7) RP8/Calothrix sp.). The formulations were prepared using paddy straw compost:vermiculite (1:1) as carrier and tested as inoculants in mungbean and soybean. The effects of the formulations were evaluated in terms of microbiological, nutrient availability, and plant biometric parameters. The Trichoderma viride–Bradyrhizobium biofilm exhibited 20–45% enhancement in fresh/dry weight of plants over other microbial treatments, while the T. viride–Azotobacter biofilm exhibited highest dehydrogenase activity in the soil and nitrogen fixation. T7 RP8 recorded statistically at par yield values with the T. viride–Bradyrhizobium (T5) biofilm treatment in mungbean. In soybean, among all the treatments, the T5 biofilm recorded the highest fresh weight of plants and available N in soil at harvest. The Anabaena–T. viride biofilmed formulations proved to be the most promising for soybean, recording 12–25% enhanced yield and microbial activity (measured as dehydrogenase activity). This study highlights the promise of cyanobacterial inoculants and biofilmed biofertilizers as promising inputs for integrated nutrient management strategies in agriculture.

Photosynthesis and nutrient composition of spinach and fenugreek grown under elevated carbon dioxide concentration

The effect of elevated carbon dioxide concentration on the changes in the biomass, photosynthesis and nutrient composition was investigated in two leafy vegetables. Spinach (Spinacia oleracea L.) and fenugreek (Trigonella foenum-graecum L.) plants were grown in open top chambers under either ambient (ACO2, 350 ± 50 µmol mol−1) or elevated (ECO2, 600 ± 50 µmol mol−1) CO2 concentration and analyzed 40, 60 and 80 days after exposure. The plants grown in ECO2 had higher net photosynthetic rate and lower stomatal conductance when compared with the plants grown in ACO2. ECO2 also changed the nutrient composition: a lower N, Mg and Fe contents and higher C and Ca contents were observed in the leaves of plants exposed to ECO2 than in those grown at ACO2.

Effect of plant growth regulators on evolution of ethylene and methane by different explants of chickpea

Shoot tips, cotyledonary nodes and hypocotyls of chickpea (Cicer arietinum L.) were grown on 3 media: plant induction medium (PIM), callus induction medium (CIM), and shoot induction medium (SIM). Maximum growth and differentiation was seen in PIM, whereas minimum was observed in CIM. Shoot tips which differentiated to multiple shoots evolved negligible amounts of ethylene. Maximum ethylene evolution was recorded by hypocotyls in PIM. Ethylene appears to have stimulatory effect on shoot bud differentiation in cotyledonary nodes. But in hypocotyls, increased ethylene inhibited growth and differentiation. Calli on media containing only auxin (PIM) evolved significantly more ethylene, whereas those on media with cytokinin (SIM) evolved more methane. Callus forming explants like cotyledonary nodes and hypocotyls evolve more ethylene than shoot tips.

Impact of Climate Change on Agricultural Productivity

The emerging uncertainties due to climate change and climatic variability are likely to aggravate the problems of future food security by exerting pressure on agriculture. Simulation models project an increase of 1.8–4.0 °C in global surface air temperatures in the next few decades that will result in large yield reductions in many regions. These increases in temperature will probably offset the likely benefits of increasing atmospheric concentrations of carbon dioxide on crop plants. The researchers face an immense challenge of meeting the needs of future generations in the face of both population growth and climate change. The development of climate smart crops needs to be considered on priority as it will make researchers and farmers proactive for the impending adversaries. However, the development of improved cultivars raised to improve yields and enhance adaptation to climate change will have to be complemented by improved crop and agronomic practices. This chapter focuses on the impact of climate change on growth and yield of the food security crops, viz., rice and wheat. Sustainable agronomic and resource management practices that can contribute to climate change mitigation have also been discussed.

Physiological Response of Maize Under Rising Atmospheric CO2 and Temperature

The projections for future climate change may have a strong influence on agricultural productivity. Maize, being a C4 plant, has evolved to adapt to the atmospheric CO2 concentration with higher photosynthetic efficiency than C3 plants. It is believed that C3 plants would gain a competitive advantage under increasing CO2, but studies indicate that C4 plants sometimes perform better due to improved water use efficiency at the ecosystem level. C4 plant species have higher temperature optima for growth than C3 plants. Temperatures above this range can affect the photosynthetic machinery, thereby decreasing growth. Despite the indication about the improvement in growth of C4 plants under increasing CO2 levels, the contribution of other factors still remains unclear in maize. This compilation is an attempt to highlight the factors and processes affected by climate change in maize and the areas of research that need to be strengthened to understand the underlying mechanisms.