Seed Hydropriming Duration for Potential Seedling Vigour in Pigeon Pea [Cajanus cajan (L.) Millsp.], Sunflower (Helianthus annuus L.) and Rice (Oryza sativa L.)

Abstract

Background: In the climate change scenario, the increasing frequency of drought is the major constraint for crop yields. Under rainfed conditions, the most vulnerable stage of the crop cycle is seed germination and seedling establishment. One of the approaches to enhance the seedling establishment is hydropriming or seed hardening. Hydropriming is a recommended practice for rainfed crops to improve the appropriate crop stand and productivity. For effective hydropriming, the priming duration is crucial because a lesser duration of priming will be ineffective, a longer duration will damage the seed coat, embryonic axis and the seed will fail to germinate. The detailed investigation on optimal priming duration in major pulse (pigeon pea), oilseed (sunflower) and cereal (rice) is scanty. Methods: Hence, the effect of priming duration on the imbibition rate and seedling establishment in major pulse (pigeon pea, cv. BRG-5), oilseed (sunflower hybrid, KBSH-78) and food crop (rice, cv. MTU-1001) was conducted in the laboratory, Department of Crop Physiology, University of Agricultural Sciences, Bangalore, India during the year 2020. The experiment was laid out in a completely randomized design with 14 soaking period treatments and five replications for imbibition studies and three replications for seedling establishment in the field. Result: The imbibition rate was rapid in the beginning hours and reached zero by 10 to 12 hours. The cumulative imbibition of 30-40% was attained in the first 2-3 hours of priming in pigeon pea and sunflower and 11 hours in rice. Similarly, 2-3 hours of hydropriming resulted in higher SVI-II (field establishment), but a 7-8 hour period of priming showed the highest seedling growth and seedling vigor index in all three crops. Therefore, 3-hour hydropriming is critical and can be extended to 7-8 hours for better seedling establishment in pigeon pea, sunflower and rice.