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ThesisItem Open Access Characterisation of boron deficient coconut palms (Cocos nucifera L.)(Department of Plantation Crops and Spices, College of Agriculture, Vellayani, 2017) Athulya, S Nair; KAU; Sreekala, G SThe experiment entitled ‘‘Characterisation of boron deficient coconut palms ( Cocos nucifera L.)” was undertaken at farmer’s field in Kalliyoor panchayat of Thiruvananthapuram district during the period from April 2015 to March 2016. The objective of the study was to identify boron deficient coconut palms and predisposing factors responsible for deficiency based on the visual diagnosis and to study the morphological characters of boron deficient and healthy coconut palms. The survey was conducted among hundred coconut palms in Kalliyoor panchayat of Thiruvananthapuram district to identify coconut palms deficient in boron based on visual symptoms listed by CPCRI. Based on the symptoms a ten scale score was developed and boron deficient palms were categorized as mild, moderate and severe intensity and compared with soil and plant boron status . The field, soil , plant characteristics and management aspects of coconut palms deficient in boron were identified based on questionnaire prepared. The morphological and yield parameters were observed at 45 days interval for one year in five palms each from mild, moderate and severe intensity and was compared with healthy palms. The results of the survey showed that the boron deficiency in palms were restricted to age group between 20-45 years grown on red loam soil with pH 6.0-7.5. The deficiency symptoms were common in coconut fields where intercropping was practiced (63 %) and in other fields with poor agronomic management (37 %). Mite and coreid bug attack were prominent ( 89 % and 53 % respectively). Diseases among deficient palms were restricted to 26 percentage and leaf rot was the major one. Common visual symptoms of palms with mild intensity were reduced leaf size, length. hooked leaves, fused leaves, and leaflets with relatively higher internodal Necrotic inflorescence, reduced nut set, poor nut size, nuts with hen and chicken symptoms and crowded crown were prominent in moderate to severely intensity groups. The morphological and yield parameters of selected palms of four groups indicated significant difference between palms of healthy and severe intensity for number of leaves, leaflet internodal length, number of female flowers per bunch of unfertilized inflorescence, opened and unopened spadices, bunches per palm, malformed nuts, volume of nut water, weight of embryo and shell throughout the observation period . The cortical cells of root were loosely packed for boron deficient palms of moderate and severe intensity. Nuts from healthy palms when compared with that from the mild, moderate and severe intensity differed significantly with respect to weight of unhusked nut, weight of husked nut, nuts set per bunch, nuts per palm per year, polar and equatorial diameter of unhusked nut, thickness of husk , weight of opened nut, thickness of meat, weight of kernel ,weight of copra and oil content and the difference was proportional to enhancement in intensity of deficiency. The available boron status in soil and plant were significantly superior in healthy palms. Identification of predisposing factors revealed poor agronomic management, intensive cultivation and low organic matter resulted in B deficieny in Coconut growing areas. The results indicated that B had marked influence in enhancing the yield characteristics of coconut particularly of thickness of meat, weight of kernel, weight of copra, oil content etc. There is a significant reduction in the yield of deficient coconut compared to that of healthy palms. The study thus substantiate the importance of boron in the nutrition of coconut palms.