Book of Extended summaries ISDA

International Conference on Reimagining Rainfed Agro-ecosystems: Challenges & Opportunities
during 22-24, December 2022 at ICAR-CRIDA, Hyderabad
In Assam, Tomato is usually grown during the rabi season as a rainfed crop. The soil moisture
fluctuation and low temperature during the critical crop growth stages are the major limiting
factors hindering the growth and yield of the tomato crop in Assam. Lowering both soil and air
temperatures below 17ºC during the rabi season in Assam is a common phenomenon, which is
detrimental to the growth and development, and yield of the tomato. Moreover, the daily
minimum temperature goes below 10ºC for about two months (Mid -December to Mid -
February), which adversely affects the reproductive stage of the tomato crop planted at the
normal time. On the other hand fruit production of tomato is gradually dropped as the
temperature increased by the end of the winter season. However, these problems can be
nullified up to an extent with the adoption of suitable adaptation strategies like microclimatic
modification with alteration of planting dates and application of mulches. The use of mulches
modifies the microclimate of the crop by altering not only the soil hydrothermal as well as
radiation regimes at the soil surface and within the crop canopy. Generally, polythene mulches
increase both maximum and minimum soil temperatures (Ham et al., 1993), whereas, organic
mulches decrease maximum but increase minimum soil temperature (Teasdale and Mohler,
1993) as compared to un-mulched soil. Thus, modification of the thermal environment for
increasing the yield of tomato crops seems to be very important. The study hypothesized that
the mulching and altering dates of planting would create a congenial microclimate for matching
growing periods to fit in the required microclimatic conditions and also for better growth,
development, and yield of the crop. The investigation was planned to study the effect of
modified thermal regimes on the yield of the Tomato under varying microenvironments.
Methodology
The study was carried out at the Experimental Farm of Assam Agricultural University, Jorhat,
Assam (26°42'39" N and 93°15'39" E) during rabi, 2019-20. Tomato cultivar Arka
Rakshak was grown under rainfed conditions in the split-plot design with four dates of planting
(P 1: 25th October, P 2: 14 th November, P 3: 3 rd December, and P 4: 8 th January) and three
mulching treatments (M0: Non-mulch, M1: Rice straw mulch and M2: Black polythene). Daily
meteorological data of maximum and minimum temperatures during the crop growth period
were collected from the Department of the university and converted to weekly values according
to Standard Meteorological Weeks (43 rd to 19 th weeks, 2019-20). Micrometeorological
observations such as daily morning and evening soil temperature were recorded in representing
plots. Growth parameters and phenological observations were recorded periodically. The
accumulation of heat unit (GDD) from sowing to the end of the harvest and HUE was
computed for different treatments following Medhi et al., (2019). The accumulated Day
temperature during the crop growth period was also calculated following Venkatraman (1968).
The fruit yield at maturity was recorded from a 1 m 2 area from each plot as well as from the
whole plot. Thermal indices were utilized for studying the cause-effect relationship.
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Ecosystem based approaches for climate change adaptation, ecosystem services, integrated farming system models, Land
degradation neutrality