Vol. 10, Issue 10 (2021)

Author(s):
BL Dudwal, BR Meena, SK Dudwal and AC Shivran

Abstract:
Rainfed agriculture, where crop production is exclusively dependent upon rainfall, covers about 80% of the world’s cropland, contributes 60% of the cereal grains and generates livelihood in rural areas (Samara, 2002) [16]. About 43% of 97 m ha rainfed lands are dryland in India with less than 75 cm annual rainfall. “Drylands are not only thirsty but hungry too”. The primary constraints to agricultural production in dryland areas are lack of suitable soil and water management technologies as a result of highly fragile ecosystems which further have been worsened presently due to the global climate change (NRAA, 2007) [8]. Hence, saving single droplet of water and maintaining sustained fertility levels is the great challenge in drylands. Use of transpirant suppressants and plant growth regulators would be one amongst the several alternatives in this regards (Ansary M. A. 2011) [2]. Transpiration accounts for a phenomenal loss of water from the crops as nearly 99% of the water absorbed by plants is lost through this mechanism (Prakash and Ramchandran, 2000) [17]. Transpiration can be retarded either by increasing resistance of stomata and boundary layer or by decreasing vapour pressure gradient. Materials applied to the transpiring plant surface with the aim of reducing water loss from the plants are called anti-transpirants and also known as “transpiration suppressants”. Broadly, four types of transpiration suppressants, viz. reflective, stomata closing, film forming and growth retardant types are common to reduce the rate of transpiration in arid and semi-arid zones. Plant growth regulators are organic compounds occurring naturally in plant as well as synthetic, which in small amounts is effective to arrest excessive vegetative growth, flower and fruit shedding and control of flowering thereby resulting in increased crop yields. The transpiration suppressants treated plants exhibit higher relative water content, water potential and lower temperature of leaves than control (Ansary et al., 2005) [1]. Among the transpiration suppressants, Kaolin recorded the highest leaf albedo and gained popularity in dryland research (Rana et al., 2006) [14] Hence, transpiration suppressants could be used to optimize yield levels under uneven and irregular distribution of rainfall for better crop growth, yield and water use efficiency under dry land environment. However, further extensive research works on proper sources and concentrations, timings and frequencies of application of transpiration suppressants for different crops are really needed to make the dryland farming more productive on long-run.