Keragaan Source dan Sink Tiga Varietas Kacang Tunggak (Vigna unguiculata (L.) Walp)

Abstract

Kacang tunggak (Vigna unguiculata (L.) Walp) merupakan tanaman setahun yang berasal dari Sub Saharan Afrika. Di daerah asalnya, tanaman ini merupakan peringkat kedua setelah kacang tanah sebagai kelompok kacangkacangan. Produksi kacang tunggak di Indonesia relatif rendah yaitu hanya 1,5–2 ton/ha. Hanya ada sedikit informasi tentang varietas kacang tunggak berdaya hasil tinggi, keragaan dan aktivitas source-sink, dan bagaimana meningkatkan produksi dan produktivitas kacang tunggak. Informasi mengenai hubungan source dan sink yang berhubungan dengan pengisian biji pada varietas-varietas kacang tunggak di Indonesia masih sangat terbatas. Hubungan source dan sink pada tanaman ditentukan oleh keragaan dan aktivitas source serta keragaan, aktivitas dan kompetisi diantara sink. Parameter pengamatan meliputi karakter morfologi, karakter fisiologi dan komponen hasil produksi. Karakter morfologi yang diamati meliputi jumlah bunga pertandan, jumlah tandan bunga, jumlah bunga jadi polong, dan jumlah buku, bobot kering tajuk, dan. Karakter fisiologi yang diamati meliputi rasio tajuk akar, total biomassa tanaman, kandungan klorofil, nilai kehijauan daun, suhu daun, laju fotosintesis, konduktansi stomata, laju pertumbuhan tanaman, laju asimilasi bersih dan kandungan karbohidrat total. Komponen hasil produksi meliputi bobot polong kering pertanaman, panjang polong, jumlah biji perpolong, bobot biji kering pertanaman, bobot 100 biji dan produktivitas. Pemeliharaan tanaman meliputi penyiraman, penyiangan, serta pengendalian hama dan penyakit. Kacang tunggak dipanen saat polong pada 10% populasi tanaman dalam satu tandan sudah mengering dan polong berubah warna menjadi kecoklatan. Pemanenan dilakukan mulai umur 10 minggu setelah tanam dan seterusnya setiap satu minggu sekali sampai tanaman berumur 14 minggu setelah tanam (mst). Penelitian ini dirancang dengan menggunakan Rancangan Kelompok Lengkap Teracak (RKLT) satu faktor. Faktor yang diamati adalah varietas. Varietas kacang tunggak yang digunakan yakni V1 (Arghavan IPB), V2 (Albina IPB) dan V3 (Uno IPB). Perlakuan diulang sebanyak 4 kali sehingga terdapat 12 satuan percobaan. Analisis data dilakukan menggunakan analysis of variance (ANOVA) pada taraf 5%. Data kuantitatif yang diperoleh dianalisis menggunakan uji F. Jika hasil yang diperoleh signifikan maka dilakukan uji lanjut dengan metode Duncan Multiple Range Test (DMRT) pada taraf nyata α = 5%. Selain itu dilakukan juga uji korelasi antara seluruh karakteristik tanaman terhadap produksi polong. Hasil penelitian ini menunjukkan bahwa potensi hasil biji kering kacang tunggak berkisar 20,28 – 23,98 g dan produktivitas yang dihasilkan pada varietas Arghavan sebesar 0,87 ton ha־¹, varietas Albina sebesar 0,88 ton ha־¹, varietas Uno sebesar 0,79 ton ha־¹. Hal tersebut berbeda atau lebih rendah dengan deskripsi varietas kacang tunggak, pada varietas Albina memiliki potensi hasil berkisar antara 3,88 – 4,69 ton ha־¹, varietas Arghavan berkisar antara 1,92 – 2,35 ton ha־¹ dan varietas Uno berkisar antara 5.47-5.78 ton ha־¹. Ketiga varietas yang digunakan dalam penelitian ini tidak menunjukkan perbedaan kapasitas source- ii sink pada laju fotosintesis, konduktansi stomata, laju pertumbuhan tanaman, laju asimilasi bersih dan produksi per tanaman. Perbedaannya hanya pada bobot 100 biji dimana varietas Albina memiliki bobot paling tinggi 14,16 g/100 biji. Potensi hasil produksi varietas Albina, Arghavan dan Uno masih rendah dibandingkan dengan potensi hasil yang tercantum dalam deskripsi varietas.

Cowpea (Vigna unguiculata (L.) Walp) is an annual plant originating from Sub-Saharan Africa. In its area of origin, this plant is ranked second after peanuts in the legume group. Cowpea production in Indonesia is relatively low, only 1.5–2 tons/ha. There is little information on high yielding cowpea varieties, source-sink activities and capacities, and how to increase cowpea production and productivity. Information on source and sink relationships related to seed filling in cowpea varieties in Indonesia is still very limited. The relationship between source and sink in plants is determined by performance and activity of the source as well as performance, activity and competition between the sink. Parameters observed include morphological characters, physiological characters, and production yield components. Morphological characters observed included the number of flower bunches, number of flower bunches, number of flower pods, and number of nodes, crown dry weight,. Physiological characteristics observed included root canopy ratio, total plant biomass, chlorophyll content, leaf greenness value, leaf temperature, photosynthetic rate, stomatal conductance, plant growth rate, net assimilation rate, and total carbohydrate content. Yield components include dry pod weight planted, pod length, number of seeds per pod, dry seed weight planted, 100 seed weight, and productivity. Plant maintenance includes watering, weeding, and pest and disease control. Cowpeas were harvested when the pods in 10% of the plant population in one bunch had dried and the pods had turned brown in color. Harvesting is done from the age of 10 weeks after planting and so on once every week until the plants are 14 weeks old after planting. This study was designed using a one-factor Completely Randomized Block Design (CRBD). The observed factor is variety. The cowpea varieties used were V1 (Arghavan IPB), V2 (Albina IPB), and V3 (Uno IPB). The treatment was repeated 4 times so that there were 12 experimental units. Data analysis was performed using analysis of variance (ANOVA) at the 5% level. The quantitative data obtained were analyzed using the F test. If the results obtained were significant, a further test was carried out using the Duncan Multiple Range Test (DMRT) method at a significant level of α = 5%. In addition, a correlation test was also carried out between all plant characteristics on pod production. The results of this study indicate that the yield potential of dry cowpea seeds ranges from 20.28 – 23.98 g and the productivity produced in the Arghavan variety is 0.87 tons ha־¹, the Albina variety is 0.88 tons ha־¹, the Uno variety is 0.79 tonnes ha־¹. This is different or lower than the description of cowpea varieties, the Albina variety has a yield potential ranging from 3.88 – 4.69 tons ha־¹, the Arghavan variety ranges from 1.92 – 2.35 tons ha־¹ and the Uno variety ranged from 5.47-5.78 tonnes ha־¹.The three varieties used in this study showed no difference in source-sink capacity in photosynthetic rate, stomatal conductance, plant growth rate, net assimilation rate, and production per plant. The difference is only in the weight of 100 seeds whereas the Albina variety has the highest weight of 14.16 g/100 seeds. The yield potential of the Albina, Arghavan, and Uno varieties is still low compared to the yield potential listed in the description of the variety.