Evidence for an interaction effect during in vitro rooting of oil palm (Elaeis guineensis Jacq.) somatic embryo-derived plantlets

Abstract

In vitro rooting of oil palm shoots derived from somatic embryos was achieved through a single-phase protocol in which three shoots are cultured in the same culture tube on an α-naphtaleacetic acid-enriched culture medium. Rooting performance was dependent on both the genetic origin and initial size of the shoot explants. All shoots from a given tube showed a tendency to give roots of the same type, independent of the original size of the explant. Whatever the clonal line, longer-size shoots (Ltype: >9 cm) showed higher rooting rates than medium-size (M-type: 7-9 cm) and short-size ones (S-type: 5-7 cm). When groups of three shoots from the same clonal line were rooted together in the same culture tube, the combination of plant size within the group impacted overall quality of rooting. Within triplets of shoots containing more than one short individual, the probability of obtaining adequate rooting was low. Similarly, when more than one long shoot was included in the triplet rooting, quality was also poor. By avoiding such combinations, the rate of wellrooted plantlets increased by 25%, with a maximum of 66% when triplets of S/M/L combination were used. Smaller shoots, which usually showed poor rooting performance, were therefore found to benefit from the presence of their neighbors. This interaction between the sizes of individuals in a given tube was found to be associated with a withintube correlation effect, a phenomenon previously described as "event coupling," which was estimated using a distorted binomial-type distribution of probabilities. The resulting calculation of a coupling factor (average r=0.60) explains the behavior of shoots within the same culture tube and their average rooting performance. Modeling of the interactions that occurred during in vitro rooting is described here and is recommended for improvement of this critical step in micropropagation.

Pembentukan akar in vitro planlet kelapa sawit (Elaeis guineensis Jacq.) dalam medium cair dengan penambahan auksin In vitro rooting of oil palm (Elaeis guineensis Jacq.) plantlets in a liquid medium supplemented with auxins

“…Planlet yang telah memiliki sistem perakaran yang baik akan lebih cepat tumbuh dan berkembang saat diaklimatisasi (Hazarika, 2003). Konan et al (2007) menggunakan tiga planlet kelapa sawit per tabung kultur pada medium padat dengan NAA 1 mg/L yang menghasilkan persentase pembentukan akar terbaik sebesar 66%. Untuk produksi komersial, persentase pembentukan akar planlet kelapa sawit ini masih perlu ditingkatkan.…”

“…Akar primer berwarna putihkekuningan atau putih-kecoklatan dengan akar sekunder berwarna putih sebagaimana ditunjukkan pada Gambar 3B. Konan et al (2007) berhasil menginduksi akar planlet kelapa sawit secara in vitro dalam medium MS padat modifikasi yang ditambah dengan NAA 1 mg/L. Keragaan atau kelas akar terbaik diperoleh pada umur 12 minggu.…”

“…Hasil rata-rata kelas akar yang diperoleh pada penelitian tersebut adalah kelas A sebesar 47%, kelas B sebesar 24% dan kelas C sebesar 29%. Perbedaan penentuan kelas akar pada penelitian ini dibandingkan pada penelitian Konan et al (2007) adalah adanya akar primer dengan pertumbuhan akar sekunder yang cukup baik atau lebat meskipun panjangnya < 3 cm. Bahkan ada beberapa akar primer yang jumlahnya lebih dari dua dengan pertumbuhan akar sekunder yang cukup banyak.…”

EX VITRO ROOTING OF OIL PALM (Elaeis guineensis Jacq.) PLANTLETS DERIVED FROM TISSUE CULTURE

“…Some of the plantlets are not able to form roots although they have future radicles. If the plantlets have already good aerial parts (shoots), root induction can be done in vitro in the laboratory with rooting frequency of 66-92% (Rival et al 1997;Konan et al 2007;Ibrahim et al 2009;Nizam and Te-chato 2009;Riyadi and Sumaryono 2010) or ex vitro during acclimatization period in the greenhouse or nursery.…”

EFFECT OF GAMMA IRRADIATION ON THE GROWTH AND DEVELOPMENT OF SAGO PALM (Metroxylon sagu Rottb.) CALLI

“…However, results reported by Sumaryono et al (2012) revealed that increasing the concentration of sucrose or other carbohydrates did not favor the growth and vigor of sago plantlets. Rooting of the plantlets was conducted in liquid medium as commonly performed in oil palm plantlets (Konan et al 2007). Good vigor and root system of plantlets increased the survival rate of plantlets during acclimatization.…”