BHARAT, NARENDER KROHIWALA, PARANJAY2019-11-212019-11-212019-09http://krishikosh.egranth.ac.in/handle/1/5810135857ABSTRACT The present investigation entitled “Studies on the effect of foliar application of plant defense activators on seed yield and quality in radish” was carried out in the Department of Seed Science and Technology, Dr. Y. S Parmar University of Horticulture and Forestry, Nauni, Solan (HP) during 2018-2019. Under this study radish seed crop cv. Japanese white was used and two separate experiments were conducted. Under first experiment there were 13 treatments including control viz., salicylic acid @ 50ppm (T1),salicylic acid @75ppm (T2), salicylic acid @100ppm (T3), jasmonic acid @ 55 ppm (T4), jasmonic acid @ 110 ppm (T5), jasmonic acid @ 165 ppm (T6), butyric acid @ 250ppm (T7), butyric acid @ 500 ppm (T8), butyric acid @ 750ppm (T9), potassium nitrate @ 1% (T10), potassium nitrate @ 1.5% (T11), potassium nitrate @ 2% (T12) and untreated control (T13). Three foliar applications were given, first at initiation of flowering stalk, second at flowering and third at pod development stage. The severity of alternaria blight was recorded lowest (11.79 %) in the plots sprayed with butyric acid @ 750ppm (T9) followed by 13.57 % in salicylic acid @100ppm (T3). The maximum seed yield (1063.71 kg/ha) was observed from salicylic acid @100ppm (T3) which was at par with potassium nitrate @ 2% (T12) in which the yield was 1004.59 kg/ha. The other seed yield parameters like number of siliqua/plant, length of siliqua, number of seeds/siliqua and 1000 seed weight were observed significantly higher i.e. 312.47, 7.43cm, 6.40, 17.36g respectively under salicylic acid @100ppm (T3) which was found at par withpotassium nitrate @ 2% (T12). Seed quality and health testing of harvested seed was also done following standard blotter paper method, roll paper towel method and grow out test. The maximum germination (94%), SVI-I (2,275.59), SVI-II (1,292.45) and other seed quality parameters like seedling length (24.21 cm), seedling dry wt. (13.75 mg), seedling emergence (83.75%), normal seedling (83.25%) and speed of germination (93.08) were found highest in salicylic acid @100ppm (T3) which was followed bypotassium nitrate @ 2% (T12) in which the values for the germination, SVI-I and SVI-II were 93%, 2215.99, 1222.98, respectively and for other seed quality parameters like seedling length, seedling dry weight, seedling emergence, normal seedling and speed of germination were 23.83cm, 13.15mg, 82.75%, 82.25% and 92.84 respectively.The infected seed percent (2.75%) and total seed microflora (24%) observed from salicylic acid @ 100ppm (T3) were also significantly lower as compared to control. In the second experiment, radish seed was subjected to priming treatment with different defense activators.There were 13 treatments viz. salicylic acid @ 25ppm (T1), salicylic acid @50ppm (T2), salicylic acid @75ppm (T3), jasmonic acid @ 55 ppm (T4), jasmonic acid @ 110 ppm (T5), jasmonic acid @ 165 ppm (T6), butyric acid @ 250ppm (T7), butyric acid @ 500 ppm (T8), butyric acid @ 750ppm (T9), potassium nitrate @ 1% (T10), potassium nitrate @ 2% (T11), potassium nitrate @ 3% (T12) and Control (T13). The primed seeds were evaluated for seed quality and health parameters. The maximum germination (95.50%), SVI-I (2217.10) & SVI-II (1248.37) and other parameters were found significantly superior in potassium nitrate @ 2% (T11) which was observed at par with salicylic acid @ 50ppm (T2). Thus it can be concluded from the study that foliar application of plant defense activators like salicylic acid @ 100 ppm or potassium nitrate @ 2% at three stages were effective in reducing the severity of alternaria blight (52.04% & 44.80% respectively) and increasing the seed yield (27.30% & 20.23% respectively) and other seed quality parameters in radish seed crop cv. Japanese white as compared to control. Also seed priming with plant defense activators like potassium nitrate @ 2% or salicylic acid @ 50 ppm were effective treatments in enhancing the seed quality parameters inradish.ennullThesis