Kajian Agronomis Kedelai Toleran Naungan di Bawah Kelapa Sawit

Abstract

Soybean production is always below national consumption, one solution is the expansion of soybean crops. Land use among oil palm plantations is an alternative but it is necessary to look for shade resistant soybean varieties that are suitable to be planted and at what age can oil palm plantations be planted in intercropping. The main objective of this study is to obtain selected and high yielding varieties that are able to adapt under the auspices of oil palm planting. The specific purpose of this study was to obtain a pattern of interception of light under the oil palm canopy based on the age of planting; identify morphological, anatomical, physiological and biochemical characters and soybean yield components that are closely correlated due to shade; get the best varieties of soybeans to be planted under oil palm plantations; identify growth and production of soybeans planted under different age-old oil palm plantations with square and triangular cropping systems. This study consisted of 5 stages, namely (1) the pattern of light interception in oil palm plantations by measuring the intensity of light on the palm oil of Tenera varieties from the age of 2 to 20 years (age interval 2 years) by putting 4 Luxmeter at three points namely at left, on the right and in the middle of the row of oil palm trees and the fourth luxmeter placed in the open as a comparison, recording the results for the four tools is carried out simultaneously in the morning, afternoon and evening; (2) the determination of the best varieties under shade based on morphological, anatomical, physiological and production characters by means of six soybean varieties treated at four artificial shade levels of 0% (without shade), 30%, 50% and 70%; (3a) the determination of the best varieties under the shade of the first stage by means of four selected varieties treated at four artificial shade levels of 0% (without shade), 20%, 40% and 60%; (3b) the second stage of planting is the same as planting the first stage using seeds from the first planting seed; (4) agronomic studies of soybean growth and production under 4 and 16 year old oil palm plantations using one tolerant variety (Anjasmoro) and one sensitive variety (Later) based on previous tests, tried with two four eye planting systems and five eyes among palm oil row. The results obtained are the pattern of sunlight penetration in oil palm plantations based on the age of planting can be divided by (a) light shade at the age of 2 - 6 years; (b) heavy shelter at the age of 8-14 years; (c) moderate shelter at the age of 16-20 years. A difference in shade level showed a strong correlation on plant length, leaf area, amount of chlorophyll a and b, amount of light in leaves, clean photosynthesis, flowering age, number of productive branches, the weight of 100 seeds, seed protein content and seed fat content. Morphological and physiological characters do not always correlate with agronomic characters. Seed weight per plant is positively correlated with clean photosynthesis. The dry weight of 100 seeds was positively correlated with plant height, mean segment length, leaf greenery, and total leaf sugar. But increasing leaf area, number of productive branches, and canopy dry weight and getting late at the age of flowering will reduce seed weight per plant and dry weight of 100 seeds. Further tests showed that flowering age and weight of 100 seeds were genetic while the amount of chlorophyll, production per plot, number of pods, number of seeds per plant were strongly influenced by the environment Anjasmoro variety has the advantage of spreading growth so that the amount of light received by the leaves is highest among all varieties and produces clean photosynthesis which is the highest among all varieties tested. The results obtained that Anjasmoro and Pangrango varieties provide the best results when planted under shade, the Tanggamus variety is not good while the Later variety is sensitive to shade. Anjasmoro variety has the advantage of spreading growth so that the amount of light received by the leaves is highest among all varieties and produces clean photosynthesis which is the highest among all varieties tested. The results obtained that Anjasmoro and Pangrango varieties provide the best results when planted under shade, the Tanggamus variety is not good while the Later variety is sensitive to shade In general, the growth and yield of soybeans are lower at the location of oil palm at the age of 16 years (shelter 40-50%) compared to the age of 4 years (shelter 20-30%). Planting soybeans under oil palm shade conditions with a 25 x 25 cm cropping system show better growth and yield compared to the 25 x 25 cm triangle system. Planting soybeans under oil palm shade conditions show that Anjasmoro varieties with large seeds have a higher number of leaves and weigh 100 seeds compared to the Nanti variety with small seeds. The fertility of oil palm plantations increases after being planted with soybeans. Suggestions from this study are based on light interception and the condition of oil palm plantations in fact soybeans can be planted in the rows of ages 2 to 6 years and over 14 years. Although soybean yield was reduced by almost 50% in oil palm plantations aged 16 years but soybeans were still able to produce. In order not to interfere with harvesting activities it is recommended to plant soybeans on dead soils that have been treated twice. Use varieties that have been proven to be genetically high yielding such as Anjasmoro with a 25 x 25 cm cropping system. For the efficiency of land use and ensuring self-sufficiency in soybeans, this is feasible. However, for certain locations with different land problems, an assessment is needed.

Produksi kedelai selalu berada di bawah konsumsi nasional, salah satu solusi adalah perluasan pertanaman kedelai. Pemanfaatan lahan di antara pertanaman kelapa sawit menjadi salah satu alternatif namun perlu dicari varietas kedelai tahan naungan yang cocok ditanam dan pada umur pertanaman kelapa sawit berapa dapat ditanam kedelai secara tumpangsari. Tujuan utama penelitian ini untuk memperoleh varietas terpilih dan berdaya hasil tinggi yang mampu beradaptasi di bawah naungan penanaman kelapa sawit. Tujuan khusus penelitian ini adalah mendapatkan pola intersepsi cahaya di bawah kanopi kelapa sawit berdasarkan umur tanamnya; mengidentifikasi karakter morfologi, anatomis, fisiologis dan biokimia serta komponen hasil kedelai yang saling berkorelasi erat akibat penaungan; mendapatkan varietas terbaik kedelai untuk ditanam di bawah pertanaman kelapa sawit; mengidentifikasi pertumbuhan dan produksi kedelai yang ditanam di bawah pertanaman kelapa sawit yang berbeda umur dengan sistem tanam persegi dan segitiga. Penelitian ini terdiri atas 5 tahap yaitu (1) pola intersepsi cahaya pada pertanaman kelapa sawit dengan mengukur intensitas cahaya pada di bawah kelapa sawit varietas Tenera mulai umur 2 sampai 20 tahun (interval umur 2 tahun) dengan meletakkan 4 buah Luxmeter pada tiga titik yakni di kiri, di kanan dan di tengah barisan pohon kelapa sawit dan luxmeter ke-empat diletakkan di tempat terbuka sebagai pembanding, pencatatan hasil untuk keempat alat dilakukan secara serentak pada pagi, siang dan sore; (2) penentuan varietas terbaik di bawah naungan berdasarkan karakter morfologi, anatomi, fisiologi dan produksi dengan cara enam varietas kedelai diperlakukan pada empat tingkat naungan buatan 0% (tanpa naungan), 30%, 50% dan 70%; (3) penentuan varietas terbaik di bawah naungan pada tanam pertama dengan cara empat varietas terpilih diperlakukan pada empat tingkat naungan buatan sebesar 0% (tanpa naungan), 20%, 40% dan 60%; (4) penanaman kedua sama dengan tanam pertama menggunakan benih keturunan tanam pertama; (5) kajian agronomis pertumbuhan dan produksi kedelai di bawah pertanaman kelapa sawit umur 4 dan 16 tahun dengan cara satu varietas toleran (Anjasmoro) dan satu varietas peka (Nanti) dicobakan dengan dua sistem tanam mata empat dan mata lima di antara barisan kelapa sawit. Hasil yang diperoleh adalah pola penetrasi cahaya matahari pada pertanaman kelapa sawit berdasarkan umur tanamnya dapat dibagi dengan (a) penaungan ringan pada umur 2 – 6 tahun; (b) penaungan berat pada umur 8 - 14 tahun; (c) penaungan sedang pada umur 16 – 20 tahun. Perbedaan taraf penaungan memperlihatkan korelasi yang kuat pada panjang tanaman, luas daun, jumlah klorofil a dan b, jumlah cahaya di daun, fotosintesis bersih, umur berbunga, jumlah cabang produktif, bobot 100 biji, kadar protein biji dan kadar lemak biji. Karakter morfologi dan fisiologi tidak selalu berkorelasi dengan karakter agronomi. Bobot biji per tanaman berkorelasi nyata positif dengan fotosintesis bersih. Bobot kering 100 biji berkorelasi nyata positif dengan tinggi tanaman, rataan panjang ruas, kehijauan daun dan total gula daun. Tetapi meningkatnya luas daun, jumlah cabang produktif, dan berat kering tajuk dan semakin terlambat umur mulai berbunga akan menekan bobot biji per tanaman dan bobot kering 100 biji. Uji lanjut menunjukkan bahwa umur berbunga dan bobot 100 biji bersifat genetis sedangkan jumlah klorofil, produksi per plot, jumlah polong, jumlah biji per tanaman sangat dipengaruhi oleh lingkungan Varietas Anjasmoro mempunyai keunggulan dari pertumbuhannya yang menjalar sehingga jumlah cahaya yang diterima daun tertinggi diantara semua varietas dan menghasilkan fotosintesis bersih yang nyata tertinggi diantara semua varietas yang diuji. Hasil yang diperoleh bahwa varietas-varietas Anjasmoro dan Pangrango memberikan hasil terbaik bila ditanam di bawah penaungan, varietas Tanggamus kurang baik sedangkan varietas Nanti peka terhadap naungan Secara umum pertumbuhan dan hasil kedelai lebih rendah pada lokasi kelapa sawit umur 16 tahun (penaungan 40 – 50%) dibandingkan dengan umur 4 tahun (penaungan 20 – 30%). Penanaman kedelai di bawah kondisi naungan kelapa sawit dengan sistem tanam persegi 25 x 25 cm menunjukkan pertumbuhan dan hasil lebih baik dibandingkan dengan sistem segitiga 25 x 25 cm. Penanaman kedelai di bawah kondisi naungan kelapa sawit menunjukkan varietas Anjasmoro yang berbiji besar mempunyai jumlah daun dan bobot 100 biji lebih tinggi dibanding varietas Nanti yang berbiji kecil. Kesuburan tanah pertanaman kelapa sawit meningkat setelah ditanami kedelai. Saran dari penelitian ini berdasarkan intersepsi cahaya dan kondisi lahan pertanaman kelapa sawit sebenarnya kedelai dapat ditanam pada barisan umur 2 sampai 6 tahun dan di atas 14 tahun. Walau hasil kedelai berkurang hampir 50 % pada pertanaman kelapa sawit umur 16 tahun tapi kedelai masih mampu berproduksi. Agar tidak mengganggu aktivitas panen maka disarankan penanaman kedelai dilakukan pada tanah gawangan mati yang telah diolah tanah dua kali. Gunakan varietas yang telah terbukti secara genetis berdaya hasil tinggi seperti Anjasmoro dengan sistem tanam persegi 25 x 25 cm. Untuk efisiensi penggunaan lahan dan menjamin swa sembada kedelai hal ini layak dilakukan. Namun untuk beberapa lokasi tertentu dengan masalah tanah yang berbeda perlu dilakukan pengkajian.