KADAR FOSFOR DAUN JARAK PAGAR (Jatropha curcas L.) DAN KORELASINYA DENGAN FOSFOR TANAH TERSEDIA DARI BEBERAPA METODE EKSTRAKSI

ABSTRAKPercobaan untuk mengetahui kesesuaian beberapa metoda uji Ptanah untuk tanaman jarak pagar (Jatropha curcas L.) dan pengaruhberbagai dosis pupuk P terhadap kadar P daun dan berat kering tanamanterhadap jarak pagar telah dilakukan pada tanah Ultisol Citayam, Bogor.Percobaan dilakukan di Rumah Kaca Balai Penelitian Tanaman Rempahdan Aneka Tanaman Industri Pakuwon, Jawa Barat, dari bulan September2006 sampai Juni 2007. Perlakuan terdiri atas dosis P (SP-36), yaitu 0, 50,100, dan 150 mg P O2 5 /kg tanah, yang disusun dalam Rancangan AcakLengkap (RAL) dengan empat ulangan. Hasil penelitian menunjukkanbahwa kadar P daun dan berat kering tanaman jarak pagar meningkatsejalan dengan dosis pupuk P yang diberikan. Peningkatan dosis pupuk Pjuga diikuti oleh peningkatan kadar P tanah yang diekstraksi denganmetoda Olsen-P, Bray-1 P, dan HCl 25%. Nilai-nilai kadar P tanah tersediayang diukur dengan ketiga metoda uji P tanah tersebut mempunyai hubungan yang nyata dengan kadar P tanah yang diekstraksi dengan determinasi (R 2 ) tertinggi ditunjukkan oleh persamaan regresi dari nilai-nilai P tanah dengan metoda Bray-1 P (R 2 = 0.92) dibandingkan denganmetoda Olsen-P dan HCl 25%, yang menunjukkan bahwa metoda ujitanah Bray-1 P lebih sesuai untuk penyusunan rekomendasi pemupukan Puntuk tanaman jarak pagar di tanah Ultisol.Kata kunci: Jatropha curcas L., P daun, metode uji P tanah, hubunganantara P daun dan P tanahABSTRACTA study was conducted to compare the suitability of several soil Ptest methods for physic nut (Jatropha curcas L.) and to determine theeffect of various doses of P fertilizer on the leaf P content and the plant drymatter on Ultisol Citayam, Bogor. The experiments were carried out in aglasshouse from September 2006 up to July 2007. The employedtreatments, namely 0, 50, 100, and 150 mg P O2 5 /kg soil (in form of SP-36),were arranged in a Completely Randomized Design (CRD) with fourreplications. The results showed that the leaf P content and plant drymatter of physic nut on Ultisol increased in line with increasing doses of Pfertilizer applied. Increase of P fertilizer P rates was also followed by theincrease of soil P concentrations extracted by the three soil P test methods(Olsen-P, Bray-1 P, and HCl 25%). The values of available soil P concentration measured by the three soil P test methods had significant relationship with leaf P contents. The highest coefficient of determination (R 2 ) showed by the regression equation of available soil P concentrationmeasured by the Bray-1 P (R 2 = 0,92) compared to those measured by theOlsen-P and HCl 25% methods, indicated that the Bray-1 P method islikely  more  suitable  to  be  used  in  establishing  P  fertilizerrecommendations for the physic nut in Ultisol.Key words: Jatropha curcas L., leaf P, soil P test methods, relationshipbetween soil P and leaf P content

Changes in Soil N, P, K, Rice Growth and Yield Following the Application of Azolla pinnata

Information on the effects of A. pinnata application on changes in nutrient availability and rice yield obtained from paddy fields of the South Lampung, Indonesia is still limited. A study was carried out to investigate the effects of different rates of A. pinnata (0; 2.5, 5.0, 7.5, and 10.0 t/ha) on changes in N, P, K concentrations in paddy soils, N uptake, rice growth and yield. The experiment was conducted on a well-irrigated paddy field that was incorporated with A. pinnata, and then rice seedlings of Ciherang variety had been grown on it from June up to December 2009. The results showed that the application of A. pinnata to the paddy rice fields affected the soil available P, plant height, tiller number, grain number per panicle, and grain yield. The addition of A. pinnata at the rate of 5.0 and 7.5 t/ha had higher rice yield compared with other treatments. The application of A. pinnata at the rate of 7.5 t/ha increased significantly soil available P, indicating that A. pinnata required a fairly high P to grow optimally. The application of A. pinnata at the rate of 7.5 t/ha gave also the highest dry grain yield, suggesting that the application of A. pinnata did not suppress the rice yield, even it might help to conserve fossil fuels and foreign exchange as well as allow more paddy fields that can be fertilized by N. Practically, the application rate of A. pinnata could range 4-8 t/ha, depending on the abundance of the material at the site. Keywords: Azolla pinnata, organic matter, rice growth and yield, soil nutrient

POSISI CONTOH DAUN UNTUK ANALISIS STATUS FOSFOR (P) PADA BIBIT JARAK PAGAR (Jatropha curcas L.) DAN KADAR P TERSEDIA PADA DAERAH PERAKARANNYA

ABSTRAKStatus P pada tanaman dapat diduga dengan menganalisis kadar Ppada daun, karena daun merupakan suatu bagian tanaman yang sangataktif. Untuk itu, diperlukan informasi posisi daun yang sesuai untukdijadikan contoh daun untuk analisis status P tanaman. Percobaan inibertujuan untuk menentukan posisi daun yang sesuai untuk analisis statusP dan mempelajari perbedaan antara kadar P tersedia di tanah dan dirhizosphere, serta hubungannya dengan kadar P daun bibit jarak pagar.Percobaan dilakukan di rumah kaca Balai Penelitian Tanaman Rempahdan Aneka Tanaman Industri (Balittri) Pakuwon, Sukabumi, Jawa Barat,pada September 2006 sampai dengan Juli 2007, disusun dalam rancanganacak lengkap (RAL) dengan 3 (tiga) ulangan. Setiap unit percobaan terdiriatas 20 tanaman. Perlakuan yang diuji adalah: (a) daun ke-1 atau daunyang terletak tepat di bawah kuncup daun yang belum mekar sempurna,(b) daun ke-2 atau daun yang terletak setelah/di bawah daun ke-1, (c) daunke-3, dan (d) daun ke-4. Parameter yang diamati adalah kadar P daun (%),kadar P tersedia di tanah dan rhizosphere yang diukur dengan metodeBray-1 P. Hasil penelitian menunjukkan bahwa daun ke-2 adalah posisidaun yang sesuai sebagai contoh daun untuk analisis status P pada bibitjarak pagar (Jatropha curcas L.). Kadar P di rhizosphere lebih rendahdaripada kadar P di tanah (Bray-1P) yang jauh dari akar jarak pagar. Padadaun ke-2, keeratan hubungan yang ditunjukkan oleh koefisien regresi (R2)antara kadar Bray-1 P di rhizosphere dan kadar P daun jarak pagar (R2 =0.394) lebih tinggi daripada hubungan antara kadar Bray-1 P di tanah dankadar P daun (R2 = 0.371), sehingga untuk keperluan menggambarkanketersediaan P tanah atau untuk melihat hubungan P tanah tersedia dengankadar ataupun serapan P tanaman jarak pagar, akan lebih tepat bila contohtanah yang diambil berasal dari rhizosphere akar tanaman.Kata kunci: Jarak pagar (Jatropha curcas L.), posisi daun, status P, Ptanah tersediaABSTRACTDetermination of leaf sample position for analysis of Pstatus in physic nut (Jatropha curcas L.) seedlings andthe available P in the root zoneStatus of P in plants can be quantified by analyzing concentrationsof the nutrient in leaf as the leaf is the most active plant part. For this,information on appropriate leaf position as samples for analysis of P statusin the plants is needed. A research was conducted with aims to determinean appropriate leaf position of physic nut seedlings and to studydifferences between the concentrations of available P (Bray-1 P) in thebulk soil and the rhizosphere, along with their relationships with theconcentrations of leaf P. The experiment was carried out in a glasshouse ofIndonesian Spices and Other Industrial Crops Research Institute,Sukabumi, West Java, from September 2006 to July 2007. The experimentwas arranged in a completely randomized design with three replications.Each experimental unit consisted of 20 plants. The treatments were: (a) 1stleaf or a leaf located exactly below the shoot, (b) 2nd leaf or a leaf locatedbelow the 1st leaf, (c) 3rd leaf, and (d) 4th leaf. All the leaves were takenfrom the primary branch of the plants. Parameters measured were Pconcentrations in the leaf, P concentrations in the bulk soil and therhizosphere (Bray-1 P). The results showed that the 2nd leaf position wasthe appropriate leaf position to be taken as samples for the leaf analysis ofP status in physic nut (Jatropha curcas L.) seedlings. The concentrationsof Bray-1 P in the rhizosphere were lower than that in the bulk soil, whichis further away from the roots. The R2 values for the relationships betweenthe Bray-1 P concentrations in the rhizosphere and the the 2nd leaf Pconcentrations were higher than that between the Bray-1 P concentrationsin the bulk soil and the 2nd leaf P concentrations, hence, for the objectivesto show the soil P availability or to show the relationships between theavailable soil P and the concentrations or the P uptake by the physic nut, itwill be more accurate if the soil samples are taken from the rhizosphere.Key words: Physic nut (Jatropha curcas L.), leaf position, P status,available soil

Keragaan Penyuluhan Mendukung Usahatani Padi Sawah di Wilayah Lampung

Rice farming is still the economic support of most farmers wetland in the area of Lampung. Efforts to implement innovations related to rice farming tend to still need guidance and counseling. Aspects of extension submitted are expected according to the interests and needs of farmers. How is the extension to farmers in assisting rice farming so far not yet known for certain. Therefore, the purpose of this study is to describe the extent of extension care that occurred in Lampung area related to rice farming. The object of the study is the extension condition in rice production center of Lampung province area covering 16 sub-districts in 3 regencies: Lampung Tengah District (Sub-district: Trimurdjo, Seputih Raman, Seputih Surabaya), South Lampung District (Sub-district: Sragi, Palas, Natar Sub-district), Tanggamus District (Sub-district: Pugung, Talang Padang, Pulau Panggung), Pringsewu District (Sub-distric: Pringsewu, Pardasuka, Sukoharjo, Pagelaran, Banyumas, Gading Rejo, Ambarawa). The source of data is the farmers as the object of extension activities. Method of implementation with survey of data mining through discussion and interview in a structured.Number of respondents 121 farmers. Data and information taken in the form of extension conditions that occurred in the area of study, among others, include aspects of extension, distribution of extension, and so forth. Data analysis and presentation are descriptive statistically. The results of the study indicate that extension activities are still actively conducted on rice farming. Aspects discussed in the extension have a wide spectrum from cultivation to post-harvest, business, fertilizer and so on. Extension models tend to be conventional. Suggestions for institutional extension of agriculture in the future are: (a) Orientation of extension should shift its paradigm from teaching, technology transfer and so on become empowerment of farming society, (b) In the future in doing extension, the officers / counselor besides mastering competence (certification etc) Related to the field of duty then it should also do first based on his own practice experience; (C) Relating to turmoil with the birth of UURI No.23 th.2016 vs.UURI No.16 th.2006, Local Government should immediately by drafting the regulation and the certainty of container extension Keywords :appearance, extension, rice farmingÂ

Diallel Analysis of Cocoa (Theobroma cacao L.) Resistance to Phytophthora palmivora in Indonesia

For the program towards the development of resistant cacao (Theobroma cacao L.) to the black pod rots disease caused by P. palmivora, the diallel crossing analysis is expected can be used to provide genetic parameters on quantitative traits. The objective of the present study was to determine genetic parameters of cacao resistance to the disease caused by P. palmivora, using half diallel crosses. The crosses used five cocoa clones as parental clones (ICCRI 3, TSH 858, DR 1, ICS 13, and Sca 6) having resistance levels from susceptible to resistant. The experiment was arranged in a Randomized Block Design with three replications. The treatments were 10 hybrids (F1) and 5 parental clones. Observation was conducted 3 days after inoculation to the spot area caused by P. palmivora infection. The results showed that there was no interaction between genes in determining the resistance to black pod rots disease caused by P. palmivora. The resistance was more affected by the additive gene action. Characters of resistant to the disease were controlled by the recessive genes. The results in the present study also showed that the dominant genes were more in the parents. It is expected that the opportunity to produce cocoa hybrid owned by ICCRI 3 and Sca 6. Furthermore, the estimated value of broad sense heritability (h2BS) and narrow sense heritability (h2NS) was high for the spot area, while, based on the disease intensity it was moderate to high. Keywords: Cocoa, genetic parameters, resistance, P. palmivor

Influence of Flooding Levels on Changes in C, N and Weight of Rice Straw in a Paddy Soil

It is imperative to have a better understanding of the effects of different flooding levels in paddy soils on changes in soil chemical properties, especially information on the N recovery and N mineralization when the rice straw is incorporated into soil as a source of soil organic matter under tropic conditions, such as in Metro, Lampung. A glasshouse study was carried out to determine the effects of different flooding levels (2.5, 5.0, 7.5, and 10.0 cm) on changes in carbon (C), nitrogen (N) contents and weight of rice straw incorporated into paddy soil. The treatments were arranged in a completely randomized block design with six replications. The results showed that C content of the rice straw at the beginning of the trial was 33–40%. These values decreased 2 weeks after flooding except for the flooding level of 10 cm the C content still decreased until 4 weeks after flooding. And then for all flooding levels the values tended to return to the initial values 8 weeks after flooding. Meanwhile, the N content at the beginning of the trial was 0.56-0.60%. The N contents for all flooding levels increased with increasing time of observation (1.34-1.48%). The C:N ratios for all flooding levels at the beginning of the trial greatly decreased until 2 weeks after flooding. Thereafter, the ratios decreased slightly until 8 weeks after flooding. Furthermore, flooding level of 2.5 cm gave the lowest weight of rice straw 8 weeks after flooding, whereas, flooding level of 10.0 cm gave the highest weight of rice straw, suggesting that the lesser the flooding level, the faster the litter decomposition rate. This confirms other findings that at the depth of 1-2 cm below water surface of a paddy field are an aerobic zone, where the litter decomposed most rapidly. Keywords: Flooding levels, decomposition, C, N, rice stra