Potensi Alelopati Asystasia gangetica (L.) T. Anderson pada Berbagai Populasi dalam Menekan Pertumbuhan dan Produksi Caisim (Brassica juncea L.)

Abstract

Asystasia gangetica (L.) T. Anderson direkomendasikan sebagai tumbuhan penutup tanah pada tanaman kelapa sawit menghasilkan, namun memiliki senyawa alelopati yang berpotensi menghambat pertumbuhan tanaman. Penelitian bertujuan mengetahui potensi alelopati gulma A. gangetica pada berbagai populasi terhadap pertumbuhan dan produksi caisim. Tanaman caisim digunakan sebagai tanaman uji. Penelitian dilakukan pada Maret hingga Juli 2022 di Agribusiness and Technology Park, IPB. Penelitian ini menggunakan rancangan acak kelompok (RAK) dengan 6 perlakuan dan 4 ulangan. Perlakuan yang diuji yaitu populasi A. gangetica 0, 1, 2, 4, 8, 16 individu per pot. Satuan percobaan berupa pot berukuran 20 cm – 13 cm (diameter – tinggi) dengan isi media tanam 2 kg. Biji A. gangetica ditanam di pot dan pada umur 2 bulan setelah tanaman dipotong setinggi 5 cm dari permukaan media. Caisim ditanam satu minggu setelah pemotongan gulma A. gangetica. Hasil penelitian menunjukkan bahwa perlakuan populasi 1 sampai 16 gulma A. gangetica per pot menekan pertumbuhan vegetatif tanaman caisim. Produksi segar, produksi kering, bobot basah akar, dan bobot kering akar pada perlakuan populasi 16 gulma A. gangetica berturut-turut berkurang sebesar 54,9%, 55,5%, 60,5% dan 54,2% terhadap kontrol. Perlakuan populasi gulma A. gangetica tidak mempengaruhi warna dan kandungan klorofil daun saat panen.

Asystasia gangetica (L.) T. Anderson is recommended as a ground cover for mature oil palms, but has allelopathic compounds that have the potential to inhibit plant growth. The aim of the research was to study allelopathic potential of A. gangetica in various populations on the growth and production of mustard greens. Mustard greens was used as a test plant. The research was conducted from March to July 2022 at the Agribusiness and Technology Park, IPB. This study used a randomized complete block design (RCBD) with 6 treatments and 4 replications. The tested treatment i.e. A. gangetica 0, 1, 2, 4, 8, 16 individuals per pot. The experimental unit was a pot measured 20 cm – 13 cm (diameter – height) with 2 kg of media content. A. gangetica seeds were planted in pots and at the age of 2 months after the plants were cut to a height of 5 cm from the surface of the media. Mustard greens was planted one week after A. gangetica was cut. The results showed that the treatment of populations of 1 to 16 A. gangetica per pot suppressed the vegetative growth of mustard greens. Production fresh weight, production dry weight, root fresh weight, and root dry weight in the treatment population of 16 of A. gangetica reduced by 54.9%, 55.5%, 60.5% and 54.2% respectively, compared with control. The A. gangetica populations treatment did not affect the color and chlorophyll content of the leaves at harvest.