POSISI CONTOH DAUN UNTUK ANALISIS STATUS FOSFOR (P) PADA BIBIT JARAK PAGAR (Jatropha curcas L.) DAN KADAR P TERSEDIA PADA DAERAH PERAKARANNYA
Authors: RIVAIE A ARIVIN , KARMAWATI ELNA , RUSLI RUSLI 
Published: June 2020

<p>ABSTRAK<br />Status P pada tanaman dapat diduga dengan menganalisis kadar P<br />pada daun, karena daun merupakan suatu bagian tanaman yang sangat<br />aktif. Untuk itu, diperlukan informasi posisi daun yang sesuai untuk<br />dijadikan contoh daun untuk analisis status P tanaman. Percobaan ini<br />bertujuan untuk menentukan posisi daun yang sesuai untuk analisis status<br />P dan mempelajari perbedaan antara kadar P tersedia di tanah dan di<br />rhizosphere, serta hubungannya dengan kadar P daun bibit jarak pagar.<br />Percobaan dilakukan di rumah kaca Balai Penelitian Tanaman Rempah<br />dan Aneka Tanaman Industri (Balittri) Pakuwon, Sukabumi, Jawa Barat,<br />pada September 2006 sampai dengan Juli 2007, disusun dalam rancangan<br />acak lengkap (RAL) dengan 3 (tiga) ulangan. Setiap unit percobaan terdiri<br />atas 20 tanaman. Perlakuan yang diuji adalah: (a) daun ke-1 atau daun<br />yang terletak tepat di bawah kuncup daun yang belum mekar sempurna,<br />(b) daun ke-2 atau daun yang terletak setelah/di bawah daun ke-1, (c) daun<br />ke-3, dan (d) daun ke-4. Parameter yang diamati adalah kadar P daun (%),<br />kadar P tersedia di tanah dan rhizosphere yang diukur dengan metode<br />Bray-1 P. Hasil penelitian menunjukkan bahwa daun ke-2 adalah posisi<br />daun yang sesuai sebagai contoh daun untuk analisis status P pada bibit<br />jarak pagar (Jatropha curcas L.). Kadar P di rhizosphere lebih rendah<br />daripada kadar P di tanah (Bray-1P) yang jauh dari akar jarak pagar. Pada<br />daun ke-2, keeratan hubungan yang ditunjukkan oleh koefisien regresi (R2)<br />antara kadar Bray-1 P di rhizosphere dan kadar P daun jarak pagar (R2 =<br />0.394) lebih tinggi daripada hubungan antara kadar Bray-1 P di tanah dan<br />kadar P daun (R2 = 0.371), sehingga untuk keperluan menggambarkan<br />ketersediaan P tanah atau untuk melihat hubungan P tanah tersedia dengan<br />kadar ataupun serapan P tanaman jarak pagar, akan lebih tepat bila contoh<br />tanah yang diambil berasal dari rhizosphere akar tanaman.<br />Kata kunci: Jarak pagar (Jatropha curcas L.), posisi daun, status P, P<br />tanah tersedia</p><p>ABSTRACT<br />Determination of leaf sample position for analysis of P<br />status in physic nut (Jatropha curcas L.) seedlings and<br />the available P in the root zone<br />Status of P in plants can be quantified by analyzing concentrations<br />of the nutrient in leaf as the leaf is the most active plant part. For this,<br />information on appropriate leaf position as samples for analysis of P status<br />in the plants is needed. A research was conducted with aims to determine<br />an appropriate leaf position of physic nut seedlings and to study<br />differences between the concentrations of available P (Bray-1 P) in the<br />bulk soil and the rhizosphere, along with their relationships with the<br />concentrations of leaf P. The experiment was carried out in a glasshouse of<br />Indonesian Spices and Other Industrial Crops Research Institute,<br />Sukabumi, West Java, from September 2006 to July 2007. The experiment<br />was arranged in a completely randomized design with three replications.<br />Each experimental unit consisted of 20 plants. The treatments were: (a) 1st<br />leaf or a leaf located exactly below the shoot, (b) 2nd leaf or a leaf located<br />below the 1st leaf, (c) 3rd leaf, and (d) 4th leaf. All the leaves were taken<br />from the primary branch of the plants. Parameters measured were P<br />concentrations in the leaf, P concentrations in the bulk soil and the<br />rhizosphere (Bray-1 P). The results showed that the 2nd leaf position was<br />the appropriate leaf position to be taken as samples for the leaf analysis of<br />P status in physic nut (Jatropha curcas L.) seedlings. The concentrations<br />of Bray-1 P in the rhizosphere were lower than that in the bulk soil, which<br />is further away from the roots. The R2 values for the relationships between<br />the Bray-1 P concentrations in the rhizosphere and the the 2nd leaf P<br />concentrations were higher than that between the Bray-1 P concentrations<br />in the bulk soil and the 2nd leaf P concentrations, hence, for the objectives<br />to show the soil P availability or to show the relationships between the<br />available soil P and the concentrations or the P uptake by the physic nut, it<br />will be more accurate if the soil samples are taken from the rhizosphere.<br />Key words: Physic nut (Jatropha curcas L.), leaf position, P status,<br />available soil P</p>