Induksi Toleransi terhadap Cekaman Kekeringan dengan PerlakuannPriming dan Coating plus Nutrisi Mikro pada Benih Jagung (Zea mays L.)

Abstract

Cekaman kekeringan merupakan salah satu cekaman abiotik utama yang mempengaruhi perkecambahan, pertumbuhan, dan produksi tanaman jagung. Benih bermutu tinggi diperlukan dalam menghadapi cekaman kekeringan. Peningkatan mutu benih dan toleransi terhadap cekaman kekeringan dapat diinduksi melalui perlakuan priming dan coating pada benih. Tujuan penelitian ini yaitu (1) untuk memperoleh perlakuan priming dan coating plus nutrisi mikro pada benih jagung dalam meningkatkan toleransi terhadap cekaman kekeringan fase perkecambahan, dan (2) meningkatkan pertumbuhan tanaman dan produksi pada kondisi cekaman kekeringan di rumah kaca. Penelitian dilaksanakan pada bulan April 2023 hingga Juni 2024 di Laboratorium Ilmu dan Teknologi Benih, Departemen Agronomi dan Hortikultura, Fakultas Pertanian, IPB, serta rumah kaca Cikabayan, IPB. Benih jagung yang digunakan varietas Lamuru dan Sukmaraga, keduanya peka kekeringan. Benih jagung diperoleh dari UPBS Balai Penelitian Tanaman Serealia, Maros, Sulawesi Selatan. Penelitian terdiri atas dua percobaan. Percobaan pertama menggunakan varietas Lamuru, disusun menggunakan rancangan petak terbagi dengan rancangan kelompok lengkap teracak (RKLT) empat ulangan. Petak utama adalah tingkat cekaman kekeringan yang terdiri atas dua taraf yaitu kontrol (tanpa cekaman) dan cekaman kekeringan dengan 10% PEG 6000. Anak petak adalah perlakuan benih yang terdiri atas 12 taraf yaitu kontrol (benih tanpa perlakuan), hydropriming, osmopriming 10% PEG, priming 6 mM Si, priming 0,075 mM Se + 10 mM Zn, priming 6 mM Si + 0,075 Se + 10 mM Zn, priming 0,8 mM melatonin, seed coating 1% natrium alginat (NaAlg), seed coating + 0,732 g Si/kg benih, seed coating + 0,014 g Se + 2,875 g Zn/kg benih, seed coating + 0,732 g Si + 0,014 g Se + 2,875 g Zn/kg benih, dan seed coating + 0,186 g melatonin/kg benih. Perlakuan terbaik hasil percobaan pertama digunakan pada percobaan kedua di rumah kaca. Percobaan kedua disusun menggunakan rancangan petak-petak terbagi dengan RKLT tiga ulangan. Petak utama adalah tingkat cekaman kekeringan yang terdiri atas dua taraf yaitu 100% kapasitas lapang (KL) sebagai kontrol dan 60% KL sebagai perlakuan cekaman kekeringan. Anak petak adalah varietas terdiri atas dua taraf yaitu Lamuru dan Sukmaraga. Anak-anak petak adalah perlakuan benih yang terdiri atas tiga taraf yaitu kontrol (benih tanpa perlakuan), priming Si + Se + Zn, dan seed coating + Si + Se + Zn. Hasil percobaan pertama menunjukkan bahwa cekaman kekeringan dengan 10% PEG menurunkan nilai parameter perkecambahan benih jagung. Perlakuan benih dengan nutrisi mikro (Si, Se, Zn) melalui seed priming dan coating meningkatkan viabilitas dan vigor benih jagung pada kondisi cekaman kekeringan yaitu daya berkecambah, kecepatan tumbuh benih, bobot kering akar, bobot kering kecambah normal, dan laju pertumbuhan kecambah. Pada kondisi normal, seed coating + Si + Se + Zn mampu meningkatkan bobot kering kecambah normal jagung. Hasil percobaan kedua, cekaman kekeringan 60% KL menurunkan pertumbuhan dan produksi tanaman jagung. Varietas Lamuru memiliki tinggi tanaman lebih rendah dan pada 60% KL diameter batang lebih kecil pada awal pertumbuhan, namun diameter batang lebih besar dibandingkan Sukmaraga pada 100% KL enam minggu setelah perlakuan cekaman. Varietas Lamuru memiliki kandungan prolin daun lebih tinggi, namun memiliki aktivitas enzim SOD lebih rendah dibandingkan Sukmaraga. Varietas Lamuru memiliki tinggi tanaman lebih rendah disebabkan hanya memiliki korelasi positif dengan kandungan protein terlarut, sedangkan Sukmaraga berkorelasi positif dengan protein terlarut dan aktivitas enzim SOD. Perlakuan priming Si + Se + Zn meningkatkan tinggi tanaman jagung varietas Lamuru pada 60% KL, sedangkan seed coating + Si + Se + Zn meningkatkan jumlah daun satu minggu setelah cekaman dan setelahnya tidak ada lagi pengaruh. Perlakuan seed priming dan coating plus nutrisi mikro meningkatkan kandungan prolin daun varietas Lamuru pada 100% KL, namun pada kondisi 60% KL hanya dapat ditingkatkan dengan perlakuan seed coating. Perlakuan seed coating meningkatkan kandungan prolin daun varietas Sukmaraga pada 100% KL, sedangkan pada kondisi 60% KL dapat ditingkatkan dengan perlakuan seed priming dan coating. Perlakuan seed coating plus nutrisi mikro meningkatkan kandungan protein terlarut daun jagung varietas Sukmaraga pada 100% KL, sedangkan seed priming plus nutrisi mikro meningkatkan kandungan protein terlarut varietas Lamuru pada 60% KL. Perlakuan seed coating plus nutrisi mikro menurunkan kadar MDA pada varietas Sukmaraga. Perlakuan seed priming dan coating plus nutrisi mikro meningkatkan laju fotosintesis pada kondisi 60% KL dan pada varietas Lamuru, sedangkan hanya perlakuan seed priming plus nutrisi mikro yang dapat meningkatkan laju fotosintesis pada varietas Sukmaraga. Perlakuan seed priming dan coating plus nutrisi mikro meningkatkan kadar air relatif daun. Perlakuan seed priming plus nutrisi mikro meningkatkan bobot kering akar varietas Lamuru, sedangkan perlakuan seed priming dan coating plus nutrisi mikro meningkatkan bobot kering akar varietas Sukmaraga pada 100% KL. Perlakuan seed priming dan coating plus nutrisi mikro mampu meningkatkan bobot kering akar varietas Lamuru pada kondisi 60% KL. Penggunaan seed priming dan coating plus nutrisi mikro Si + Se + Zn belum mampu meningkatkan produksi jagung.

Drought is a major abiotic stress that affects the germination, growth, and production of maize. High-quality seed is essential to face drought stress conditions. Improvement of seed quality and tolerance to drought stress can be induced by seed priming and coating. This research aimed (1) to obtain seed priming and coating plus micronutrients of maize in improving tolerance to drought stress during the germination phase, and (2) to improve the plant growth and production under drought stress in a greenhouse. This research was conducted from April 2023 to June 2024 at the Seed Quality Testing Laboratory, Department of Agronomy and Horticulture, Faculty of Agriculture, IPB, and in a greenhouse at Cikabayan, IPB. The maize seeds used in this research were Lamuru and Sukmaraga varieties, both are drought sensitive. Maize seed obtained from the Seed Source Management Unit (UPBS) of Cereal Crops Research Institute, Maros, South Sulawesi. This study consisted of two experiments. The first experiment used the Lamuru variety and was performed in a randomized complete block design (RCBD) with a split-plot arrangement and four replications. The main plot was drought stress level, which consisted of two levels, i.e., control (non-stress) and drought stress by 10% PEG 6000. The subplot was seed enhancement treatments which consisted of 12 levels: control (untreated seed), hydropriming, osmopriming 10% PEG, priming 6 mM Si, priming 0.075 mM Se + 10 mM Zn, priming 6 mM Si + 0.075 Se + 10 mM Zn, priming 0.8 mM melatonin, seed coating 1% NaAlg, seed coating + 0.732 g Si/kg seed, seed coating + 0.014 g Se + 2.875 g Zn/kg seed, seed coating + 0.732 g Si + 0.014 g Se + 2.875 g Zn/kg seed, and seed coating + 0.186 g melatonin/kg seed. The best treatment resulting from the first experiment was used in the second experiment in the greenhouse. The second experiment was performed in an RCBD with a split-split plot arrangement and three replications. The main plot was drought stress level, which consisted of two levels, i.e., 100% field capacity (FC) as control and 60% FC as drought stress treatment. The subplot was varieties, which consisted of two levels, i.e. Lamuru and Sukmaraga. The sub-sub plot was seed enhancement treatments, which consisted of three levels, i.e., control (untreated seed), priming 6 mM Si + 0.075 Se + 10 mM Zn, and seed coating + 0.732 g Si + 0.014 g Se + 2.875 g Zn/kg seed. The first experiment showed that drought stress under 10% PEG reduced the germination parameters of maize seed. Seed treatment with micronutrients (Si, Se, Zn) through seed priming and coating improved the viability and vigor of maize seed under drought stress conditions, such as germination percentage, speed of germination, root dry weight, seedling dry weight, and seedling growth rate. Under normal conditions, seed coating + Si + Se + Zn improved the seedling dry weight of maize. In the second experiment, drought stress under 60% FC reduced maize growth and production. Lamuru had a lower plant height, and under 60% FC had a smaller stem diameter in the early growth, however it had a bigger stem diameter than Sukmaraga under 100% FC six weeks after imposed stress. Lamuru had higher leaf proline content, whereas it had lower superoxide dismutase (SOD) enzyme activity than Sukmaraga. Lamuru had lower plant height due to only having a positive correlation with soluble protein content, while Sukmaraga had positive correlations with soluble protein content and SOD enzyme activity. Seed treatment with priming Si + Se + Zn improved the seedling height of the Lamuru variety under 60% FC, while seed coating + Si + Se + Zn improved the number of leaves first week after stress treatment, and after that, there was no more influence. Seed treatment with priming and coating increased the leaf proline content of Lamuru under 100% FC, while it could only be increased by seed coating under 60% FC. Seed coating increased the leaf proline content of Sukmaraga under 100% FC, while it could be increased by seed priming and coating under 60% FC. Seed coating increased the leaf-soluble protein content of Sukmaraga under 100% FC, while seed priming increased the soluble protein content of Lamuru under 60% FC. Seed coating decreased the MDA content of Sukmaraga. Micronutrients integrated in seed priming and coating increased the leaf photosynthesis rate under 60% FC and increased in the Lamuru variety, while only seed priming increased the leaf photosynthesis rate of the Sukmaraga variety. Seed priming and coating treatments increased the relative water content of leaves. Seed priming increased the root dry weight of the Lamuru variety, while seed priming and coating increased the root dry weight of the Sukmaraga variety under 100% FC. Micronutrient seed priming and coating increased the root dry weight of the Lamuru variety under 60% FC. The use of seed priming and coating plus Si + Se + Zn did not improve the maize production.