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Researcher Narayan, Pingale Bhanudas
Advisor Singh, S. D.
Source KrishiKosh-Indian National Agricultural Research System
Content type Text
Educational Degree Doctor of Philosophy (Ph.D.)
File Format PDF
Language English
Subject Domain (in DDC) Social sciences ♦ Social problems & services; associations ♦ Other social problems & services ♦ Natural sciences & mathematics ♦ Life sciences; biology ♦ Ecology
Subject Keyword Quantitative and Qualitative Response of Rice and Maize Crops To Elevated Carbon Dioxide Under Varying Nitrogen Levels ♦ Environmental Science
Abstract Rising atmospheric [CO2] may have significant impact on growth and yield, physiological processes, mineral nutrition and grain quality of many agricultural crops. Crops with the C3 and C4 photosynthetic pathway like rice and maize respectively are very important to global food supply. Various external factors such as temperature, fertilization, irrigation, etc. affect crop growth and development in complex ways. Thus to study interactive effect of CO2 and nitrogen fertilization, rice (C3) and maize (C4) crops were grown under ambient [CO2] (380 ppm, AC) and elevated [CO2] (550 ppm, EC) conditions using free air CO2 enrichment (FACE) facility. Five levels of nitrogen (N0=No external supply, N1= 50 kg ha -1 , N2=100 kg ha -1 , N3=150 kg ha -1 and N4=200 kg ha-1 ) were applied both for AC and EC treatments. Study concludes that, elevated carbon dioxide increased the responsiveness of rice and maize growth to nitrogen application by increasing the response of leaf area to nitrogen application rate. Elevated CO2 enhanced the economic as well as biological yield of both C3 (rice) and C4 (maize) crops irrespective of nitrogen levels, but the growth and yield response to CO2 fertilization was recorded to be higher in C3 crop-rice (12%) compared to C4 crop-maize (7- 9%) across the nitrogen levels. However, nitrogen response in respect of growth and yield of both the crops was found to be higher under elevated CO2 than under ambient CO2 condition. Increase in economic yield of rice and maize under elevated CO2 condition was mainly attributed to marked increase in the number of panicles per pot and slight improvement in grains per panicle, while 1000 grain weight was unaffected under same. In maize, however the CO2 fertilization enhanced the grain yield mainly by improving the number of grains per cob without affecting the number of cobs per plant and 100 grain weight. Rice being a C3 crop showed higher response to EC for net photosynthetic rate than C4 maize at flowering. This suggests that the main challenge is how to enhance sink capacity to utilize the photosynthate concurrently, in order to maximize grain yield under EC. On the other hand, stomatal conductance and transpiration rate was reduced in both the crops. Due to EC, there was slight dilution of nutrient concentration in rice but insignificant in maize. However, total nutrient uptake and their use efficiency in rice and maize was slightly higher due to increase in plant biomass under EC condition. Increased fertilization dose led to nullifying the nutrient dilution effect of EC and maintained the quality of crop biomass. Similarly, the concentration of protein reduced in rice and maize grains under EC could partially be mitigated through higher dose of nitrogen fertilization. Thus, in order to harness growth and yield response of EC viz-a- viz to maintain the quality of crop biomass, the nutrient application level needs to be revised under changing climatic scenario in future.
Educational Use Research
Education Level UG and PG
Learning Resource Type Thesis
Size (in Bytes) 2.32 MB