Pengaruh Pupuk NPK, Bahan Organik, dan Aplikasi Carbon Dots Diperkaya Nitrogen terhadap Produksi dan Mutu Benih Padi (Oryza sativa L.)

Abstract

Intensifikasi pertanian membutuhkan benih bermutu untuk meningkatkan produktivitas, namun penggunaan NPK jangka panjang dapat menurunkan kesuburan tanah. Oleh karena itu, pemupukan berimbang dengan bahan organik (BO) dan teknologi pendukung seperti carbon dots (CDs) menjadi strategi yang potensial. CDs bersifat ramah lingkungan, mudah disintesis dari limbah biomassa, dan mampu meningkatkan efisiensi pemupukan. Penelitian ini mengkaji CDs yang disintesis dari kopi (serbuk dan ampas) serta pengaruh apliksinya dengan kombinasi pupuk NPK, dan bahan organik terhadap pertumbuhan, hasil, dan mutu benih padi varietas BK Situbondo 01 Agritan. Percobaan dilakukan pada MK 2023 di Balai Besar Perakitan dan Modernisasi Pertanian Tanama Padi di Sukamandi, Subang, menggunakan Rancangan Split-split Plot dengan faktor pupuk NPK (tanpa NPK, +PK, +NP, +NK, +NPK), bahan organik (pupuk kandang, kompos jerami, tanpa BO), dan CDs (tanpa CDs, +CDs). Hasil penelitian menunjukkan bahwa CDs ampas kopi coffee shop bersifat larut air, berwarna cokelat terang, dan menunjukkan puncak absorbansi UV-Vis pada 300 nm. Doping nitrogen meningkatkan kadar N hingga 16%, menunjukkan efektivitasnya sebagai pembawa nitrogen. Nitrogen terbukti sebagai unsur pembatas utama yang berpengaruh terhadap pertumbuhan dan hasil. Kalium mempertahankan fungsi fotosintesis menjelang panen, sementara fosfor mendukung pengisian biji. Kompos jerami unggul dalam kandungan C dan N, sedangkan pupuk kandang mengandung P dan K lebih tinggi. Aplikasi CDs diperkaya nitrogen efektif meningkatkan pertumbuhan dan mutu benih terutama pada kombinasi +NP atau +NK atau bahan organik, tetapi dapat menimbulkan overstimulasi jika dikombinasikan dengan +NPK. Pemupukan parsial (+NP, +NK) yang dikombinasikan dengan bahan organik dan CDs menghasilkan pertumbuhan dan hasil benih setara dengan +NPK. Kombinasi +NP dan pupuk kandang menghasilkan benih 7,63 t ha?¹, tidak beda nyata dengan +NPK (7,76 t ha?¹). Pupuk kandang memberikan pengaruh paling stabil terhadap pertumbuhan dan hasil. Efisiensi agronomis tertinggi dicapai oleh pupuk fosfor (159,72 kg kg-1 P), diikuti nitrogen (22,58 kg kg-1 N), menandakan bahwa P merupakan faktor pembatas utama di lahan percobaan. Kombinasi nitrogen dan fosfor menghasilkan daya berkecambah, indeks vigor, dan kecepatan tumbuh yang tinggi, ketika ditambahkan dengan bahan organik mampu meningkatkan pengisian biji (bobot 1000 butir, nisbah kariopsis/sekam, berat kering kecambah). Kombinasi +NP dan CDs meningkatkan keserempakan tumbuh. Nitrogen menurunkan intensitas dormansi saat panen, meskipun persistensi dormansi tetap tiga minggu. Pemupukan parsial hara makro (+NP) yang dikombinasikan dengan pupuk kandang dan aplikasi CDs diperkaya nitrogen, direkomendasikan untuk mereduksi ketergantungan terhadap pupuk NPK lengkap tanpa menurunkan hasil dan mutu benih padi.

Agricultural intensification requires high-quality seeds to increase productivity; however, long-term use of NPK fertilizers may reduce soil fertility. Therefore, balanced fertilization involving organic matter (OM) and supporting technologies such as carbon dots (CDs) is a promising strategy. CDs are environmentally friendly, easily synthesized from biomass waste, and have the potential to enhance fertilization efficiency. This study investigates CDs synthesized from coffee (grounds and spent coffee) and their application in combination with NPK fertilizers and organic materials on the growth, yield, and seed quality of BK Situbondo 01 Agritan rice variety. The experiment was conducted during the dry season (DS) of 2023 at the Center for Rice Breeding and Agricultural Modernization in Sukamandi, Subang, using a Split-split Plot Design with three factors: NPK fertilizers (no NPK, +PK, +NP, +NK, +NPK), organic matter (manure, straw compost, no OM), and CDs (without CDs, with CDs). The results showed that CDs derived from spent coffee grounds from coffee shops were water-soluble, light brown in color, and exhibited a UV-Vis absorbance peak at 300 nm. Nitrogen doping increased the nitrogen content up to 16%, indicating its effectiveness as a nitrogen carrier. Nitrogen was identified as the primary limiting nutrient influencing growth and yield. Potassium played a role in maintaining photosynthesis near harvest, while phosphorus supported grain filling. Straw compost was superior in C and N content, whereas manure had higher P and K levels. Application of nitrogen-enriched CDs effectively enhanced growth and seed quality, especially when combined with +NP, +NK, or organic materials, but could cause overstimulation when combined with full +NPK. Partial fertilization (+NP, +NK) combined with organic matter and CDs resulted in plant growth and seed yield comparable to full +NPK. The combination of +NP and manure produced a seed yield of 7.63 t ha?¹, which was not significantly different from +NPK (7.76 t ha?¹). Manure provided the most stable effects on growth and yield. The highest agronomic efficiency was achieved with phosphorus fertilizer (159.72 kg kg?¹ P), followed by nitrogen (22.58 kg kg?¹ N), indicating phosphorus as the main limiting factor in the experimental site. The combination of nitrogen and phosphorus resulted in a high germination rate, vigor index, and growth rate. When combined with organic matter, it enhanced grain filling (as indicated by 1000-grain weight, caryopsis/hull ratio, and seedling dry weight). The +NP and CDs combination improved germination uniformity. Nitrogen reduced dormancy intensity at harvest, although dormancy persistence remained at three weeks. Partial macronutrient fertilization (+NP), combined with manure and application of nitrogen-enriched CDs, is recommended to reduce dependence on complete NPK fertilization without compromising rice seed yield and quality.