Book of Extended summaries ISDA

International Conference on Reimagining Rainfed Agro-ecosystems: Challenges &
Opportunities during 22-24, December 2022 at ICAR-CRIDA, Hyderabad
contribute to a lower rate of soil moisture depletion. In general, plants with the C4
photosynthesis pathway are more efficient in water use than plants with the C 3 photosynthesis
pathway (Bacon, 2004). Differences in TE among species are well known. However, variation
in TE within a species has been reported in maize (Jyothi et al., 2020) and blakgram (Jyothi et
al., 2017). As a C 4 crop, pearl millet possesses high TE and is well adapted to semi-arid
environments. Hybrid (ICMH-356) and open pollinated variety (OPV, ICMV-221) were
evaluated to understand the variations in water use and transpiration efficiency from sowing to
grain harvest (during Kharif in rainout shelter facility). The experiment was a completely
randomized block design with five replications. Growth observations and water balance in pots
quantified components of whole-plant TE.
Methodology
Transpiration efficiency was determined by gravimetric method with modifications. Whole
plant level TE was determined gravimetrically in 15 litres plastic pots filled with a mixture of
red soil and farm yard manure. Recommended dose of fertilizer was used. Two seeds were
planted per pot and thinned to one plant at 7 days after emergence. The pots were then covered
from both ends with poly bags. A slit was cut in the top bag to permit seedling growth. The slit
was further sealed with a piece of clear adhesive tape. The poly bags were tightly fixed onto
the pots with an elastic band. The initial weight recorded. The pots were weighed every 3 days
(from 7 days after covering with poly bags) and measured quantity of water was supplemented
through a funnel placed into the poly bag and again sealed with tape after watering. When the
plants reached maturity, they were harvested at soil level and final pot weight was recorded.
Individually plants were partitioned into leaves, stems and cobs and the dry weight was
recorded. Total water transpired was calculated by subtracting the final pot weight from the
initial weight and then adding the amount of water that has been applied at regular intervals.
TE biomass and TE seed was calculated by dividing the above ground dry biomass and seed yield
by the amount of water transpired.
Results
The water transpired was 19.02 l/p and 20.84 l/p for OPV (ICMV-221) and Hybrid (ICMH-
356) for the total growth period. The total biomass was 67.3 g/p and 107.9 g/p and seed yield
was 30.81 and 43.6 g/pl for OPV and hybrid respectively. In OPV, TE biomass and TE seed yield
was 3.54 (g biomass/1 water) and 1.61 (g seed/ l water) and increased to 5.17 and 2.09
respectively in hybrid. TEbiomass and TEseed (biomass/seed produced per unit of water transpired)
in hybrid improved by 46.0% and 29.8% respectively. High TE in hybrid was due to enhanced
biomass production (60.3%) and seed yield (41.5%) with extra water use (9.6%) as compared
to OPV (ICMV-221).
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