Longest Shoot Length Research Articles

Effects of Light Quality and Intensity on the Carbon Dioxide Exchange Rate, Growth, and Morphogenesis of Grafted Pepper Transplants during Healing and Acclimatization

This study evaluated the influence of light quality and intensity during healing and acclimatization on the CO₂ exchange rate, growth, and morphogenesis of grafted pepper (Capsicum annuum L.) transplants, using a system for the continuous measurement of the CO₂ exchange rate. C. annuum L. ‘Nokkwang’ and ‘Tantan’ were used as scions and rootstocks, respectively. Before grafting, the transplants were grown for four weeks in a growth chamber with artificial light, where the temperature was set at 25/18℃ (light/dark period) and the light period was 14 hours·d -1 . The grafted pepper transplants were then healed and acclimatized under different light quality conditions using fluorescent lamps (control) and red, blue, and red + blue light-emitting diodes (LEDs). All the transplants were irradiated for 12 hours per day, for six days, at a photosynthetic photon flux (PPF) of 50, 100, or 180 μmol·m -2 ·s -1 . The higher PPF levels increased the CO₂ exchange rate during the healing and acclimatization. A smaller increase in the CO₂ exchange rates was observed in the transplants under red LEDs. At a PPF of 180 μmol·m -2 ·s -1 , the CO₂ exchange rate of the transplants irradiated with red LEDs was lowest and it was 37% lower than those irradiated with fluorescent lamps. The CO₂ exchange rates of transplants irradiated with blue LEDs was the highest and 20% higher than those irradiated under fluorescent lamps. The graft take was not affected by the light quality. The grafted pepper transplants irradiated with red LEDs had a lower SPAD value, leaf dry weight, and dry matter content. The transplants irradiated with blue LEDs had longer shoot length and heavier stem fresh weight than those irradiated with the other treatments. Leaves irradiated with the red LED had the smallest leaf area and showed leaf epinasty. In addition, the palisade and spongy cells of the pepper leaves were dysplastic and exhibited hyperplasia. Grafted pepper transplants treated with red + blue LEDs showed similar growth and morphology to those transplants irradiated with fluorescent lamps. These results suggest that high-quality grafted pepper transplants can be obtained by healing and acclimatization under a combination of blue and red lights at a high PPF level.

Effect of Auxins on Shoot and Root Growth in an Endangered Medicinal Plant Guggal [Commiphora wightii (Arnott.) Bhand.

An investigation was carried out to study the effect of IBA and NAA on vegetative propagation of guggal[Commiphora wightii (Arnott.) Bhand.] through cuttings, at Navsari Agricultural University, Navsari. The experiment consists of ten treatments: IBA, NAA and their combination, each at 2000, 4000 and 6000 mg l-1along with control, replicated thrice. Ten cuttings per each treatment and per replication were planted. Planting media used were: sand, soil and vermicompost, in 2:1:1 ratio. Cuttings were dipped for five minutes in solutions of IBA, NAA and their combinations. Cuttings treated with 4000 mg l-1 IBA proved to be the best for shoot and root responses, viz., days taken to first sprouting (11.67 days), number of shoots per cutting (10.27), number of leaves in the longest shoot (44.07), length of longest shoot (51.69cm), diameter of the longest shoot (4.40mm), rooting percentage (61.19), number of primary roots per cutting (15.01), length of the longest primary root (26.36cm), and number of secondary roots (22.37) and length of the longest secondary root (21.40cm) per cutting. It was concluded that IBA @ 4000 mg l-1 was most effective for obtaining maximum shoot and root growth.

Enhanced resistance against Thielaviopsis basicola in transgenic cotton plants expressing Arabidopsis NPR1 gene

Black root rot, caused by Thielaviopsis basicola, is an important disease in several crops including cotton. We studied the response of Arabidopsis NPR1 (AtNPR1)-expressing cotton lines, previously shown to be highly resistant to a diverse set of pathogens, to a challenge from T. basicola. In four different experiments, we found significant degree of tolerance in the transgenic lines to black root rot. Although transformants showed the typical root discoloration symptoms similar to the wild-type control plants following infection, their roots tended to recover faster and resumed normal growth. Better performance of transgenic plants is reflected by the fact that they have significantly higher shoot and root mass, longer shoot length, and greater number of boll-set. Transcriptional analysis of the defense response showed that the roots of AtNPR1-overexpressing transgenic plants exhibited stronger and faster induction of most of these defense-related genes, particularly PR1, thaumatin, glucanase, LOX1, and chitinase. The results obtained in this investigation provide further support for a broad-spectrum nature of the resistance conferred by overexpression of AtNPR1 gene in cotton.

In vitro multiplication of rough lemon (Citrus jambhiri Lush.)

In vitro multiplication of Rough Lemon (Citrus jambhiri Lush.) was carried out from nodal segments to standardize the protocol for mass multiplication under lab conditions. It was found during experimentation that MS medium supplemented with BAP (1.5 mg/L) and malt extract 500 mg/L resulted in maximum culture establishment, number of shoots and length of longest shoot per culture in minimum time during shoot proliferation. The in vitro multiplied shoots could be best rooted in half strength medium supplemented with IBA and NAA (1.0 mg/L) each with 3 % sucrose as carbohydrate source. In vitro formed plantlets were hardened in potting mixture containing sand, soil and FYM (1:1:1) and highest survival (83.33 %) was achieved after transplantation when rooted plantlet leaves were treated with 50 % glycerol as an antitranspirant.

Ethylene inhibitors enhance shoot organogenesis of gloxinia (Sinningia speciosa).

Shoot organogenesis and plant regeneration in Sinningia speciosa were improved using ethylene inhibitors. The leaf explants were cultured on initial shoot regeneration media (MS media with BAP at 2 mg/L + NAA at 0.1 mg/L) supplemented with different concentrations of aminoethoxyvinylglycine (AVG), cobalt chloride (CoCl2), and silver thiosulphate (STS). The addition of AVG, CoCl2, and STS significantly improved the regeneration frequency giving higher shoots per explant and longer shoot length. The highest shoot growth was found when STS at 5 mg/L was incorporated with generation medium, performing highest regeneration frequency with highest number of shoots. This treatment (STS at 5 mg/L) produced 40% more shoots per explant compared to control followed by STS at 10 mg/L with increasing 37% more shoots compared to control. In the cases of AVG and CoCl2 the highest shoot number per explant was found at 1 mg/L. Treated with AVG and CoCl2 at 1 mg/L increased shoot number by 16 and 12%, respectively, compared to control. Ethylene inhibitors could be used as a possible micropropagation and plant transformation protocol in S. speciosa for plant regenerations.

Hybridization and Genetic Improvement of Mulberry Varieties

This research focused on the evaluation of Open Pollinated Varieties (OPVs) for sprouting and rooting characters growth, yield and quality for effective utilization in crop improvement for sustained mulberry biodiversity. The OPVs Alf-004, Alf018, Alf-028, S61-019, S54-019 and the Batac variety were set up in Randomized Complete Block Design with three replications. The four year pooled data were analyzed using the Analysis of Variance across season and DMRT for further test of significance. Correlation analysis was used to determine the association among yield related characters. Number of branches per plant (NoB), length of longest shoot (LLS), plant height (PH), moisture content (MC) and moisture retention capacity (MRC). Propagation characters as to sprouting percentage (s), rooting percent ®, fresh weight of roots (FWR), fresh weight of shoots (FWS), length of roots (LR), length of shoots (LS), root to shoot ratio by weight (RSR wt), root to shoot ratio by length (RSR L) and number of root (NoR) were considered. Results revealed that the best performing mulberry OPVs based on growth, yield, quality and propagation traits are Alf-004, S61-019, S54-019, S61-011 and Alf-025. These varieties are expected to contribute towards a sustained quality mulberry leaf production and biodiversity for the silk industry’s growth and development. Keywords - hybridization, genetic, mulberry varieties

Improvement of shoot morphogenesis in vitro and assessment of changes of the activity of antioxidant enzymes during acclimation of micropropagated plants of Desert Teak

The aim of the study was to develop an improved and rapid regeneration system via axillary shoot proliferation for Tecomella undulata, an important endangered medicinal tree in India. The Murashige and Skoog (MS) medium augmented with different concentrations (0.1, 0.3, 0.5, 0.7, 1.0, 2.5, 5.0, 7.5 and 10.0 μM) of Thidiazuron (TDZ) was tested for the ability to induce axillary shoot development from cotyledonary node explants excised from 7-day-old sterile seedlings. Among the tried concentrations of TDZ, 0.7 μM showed optimum response in inducing maximum number (25.00 ± 2.30) of shoots and shoot length (4.06 ± 0.58 cm) after 3 weeks of incubation. The regenerated shoots when subcultured on MS medium lacking TDZ gave twofold shoot multiplication rate with maximum number (43.00 ± 2.86) of shoots per explant and longer shoot length (7.40 ± 0.34 cm) during the fourth subculture passage. Attempts were also made to study the morphogenetic effect of medium pH and sucrose concentration on axillary shoot induction and proliferation. The highest efficiency of shoot regeneration was recorded in MS medium supplemented with 0.7 μM TDZ and 3% sucrose at pH 5.8 after 3 weeks of culture. Different concentrations of Indole-3-butyric acid (IBA) were tested to determine the optimum conditions for ex vitro rooting of microshoots. The best result was accomplished with IBA (200 μM) pulse treatment given to the basal end of the microshoots for 30 min followed by their transfer in plastic cups containing soilrite and eventually established in natural soil with 80% survival rate. During acclimatization of plants, catalase (CAT) activity increased reaching maximum at 28th day after transplantation, while superoxide dismutase (SOD) activity increased reaching a maximum in the 21 days. Likewise, changes in the glutathione reductase (GR) and Ascorbate peroxidase (APX) were also detected. The observed changes reflect the plant’s capacity to develop antioxidant mechanisms during acclimatization which determine the ability to survive in oxidative stress. The standardized protocol for mass propagation of Tecomella undulata should eliminate the dependence on natural stands of plants for pharmaceutical purposes, and will also serve as a means of conservation as the species is highly overexploited.

Phenotypic Divergence in Mulberry (Morus spp.) Germplasm Collections

To improve mulberry foliage productivity, identification of suitable genes related to agronomically important traits in the available mulberry germplasm is essential. Twenty-five indigenous mulberry accessions representing five different species of Morus from seven diverse parts of the India were evaluated via principal component analysis (PCA) for 22 aboveground and underground morphometric traits and silkworm cocoon yield during 2002–2005 in the agro-climates of Berhampore, West Bengal, India. Significant differences among germplasm accessions were observed for all 22 traits and cocoon yield. Six principal components were identified, which explained >88% of total variation. Though 18 major variables were included in the principal components, longest shoot length, leaf area, intermodal distance, green and dry leaf weight, lamina length, lamina weight, root volume, and fresh and dry root weight were recognized as important variables that had direct effect on silkworm cocoon yield. These 10 variables appeared to be minimal traits for quick selection of mulberry progenies in breeding programs. Four distinct groups of accessions obtained after a cluster analysis were partly associated with their places of origin. In addition, the study highlighted a number of distinctive morphological characters in many of the accessions studied. The identified 10 minimum morphological descriptors were expected to be highly discriminating, thus they would help in quick characterization of mulberry germplasm. In addition, the distantly related germplasm were identified on the basis of cluster analysis and can be utilized in targeted mulberry improvement programs.

Shoot development and plant regeneration from protocorm-like bodies of Zygopetalum mackayi

Stem nodal segments of a sympodial orchid, Zygopetalum mackayi, were used as explants to induce protocorm-like body (PLB) formation on a hormone-free 1/2 Murashige and Skoog (1962) modified medium (1/2MS-0) or 1/2MS supplemented with 0.045–4.54 μM 1-phenyl-3-(1,2,3-thiadiazol-5-yl)-urea [TDZ] in light. After 1 mo of culture, pale to dark green, compact and irregular nodulars of PLBs formed from the explants. For PLB induction, TDZ had no significant effect on the percentage of PLB formation but promoted mean numbers of PLBs per responding explant at 0.045–4.54 μM. For plant conversion, PLBs were transferred onto the same basal medium devoid of TDZ. After 2–3 mo of culture, these PLBs successfully formed shoots and then roots with normal morphology. For PLB proliferation, TDZ has no significant effects on the fresh weight of PLB aggregates, but there is significantly retarded shoot development at 0.45–4.54 μM after 1 mo of culture. When transferring these PLB aggregates onto hormone-free medium for plant conversion, PLBs derived from TDZ-containing medium showed a decrease of shoot length (0.86–2.08 cm in shoot length) compared to those derived from 1/2MS-0 (2.74 cm in shoot length) after 1 mo of culture. Gibberellin A3 [GA3] at 0.29–8.66 μM significantly retarded PLB proliferation, but at 0.03 and 0.29 μM resulted in longer shoot length than the control treatment. Histological studies reveal that shoot development originated from the outer region of PLB aggregates. The young shoots initially connected to each other at their basal tissues with the parental PLBs. Plants were successfully obtained from PLBs and then gradually became more loosely connected with each other as well as with the parental aggregates. Several dozen plants were acclimatized in the greenhouse and showed normal morphology.

Growth Regulators Effects on In Vitro Shoot Regeneration of Sainfoin (Onobrychis Sativa Lam.)

ABSTRACTThe effect of different concentrations of BAP (6-benzylaminopurine)-NAA (a-naphthaleneacetic acid) on in vitro propagation from cotyledon node explant of sainfoin (Onobrychis sativa Lam.) was studied. The developed large numbers of shoots were propagated from explants within 6 weeks on Murashige and Skoog (MS) media. The longest shoot length (6.79 cm) was recorded on MS medium containing 1 mg/l BAP, 0.02 mg/l NAA. The observed difficulties were overcome after pulse treatment with 50 mg/l IBA for 10 min on MS medium for rooting.

Efficient In-Vitro Regeneration from Mature Leaf Explants of Scoparia dulcis L., an Ethnomedicinal Plant

ABSTRACT A plant regeneration protocol via multiple-shoot induction using leaf explants from field-grown mature plants of Scoparia dulcis L. (Scrophulariaceae), an ethnomedicinal plant, was established. Explants were cultured on Murashige and Skoog (MS) medium with different concentrations of 6-benzylaminopurine (BAP, 13.2, 17.6 and 22.2 μM) in combination with indole-3-acetic acid (IAA, 0.5 and 2.8 μM) or napthalene-3-acetic acid (NAA, 0.5 and 2.6 μM). The maximum number of shoots (14.0 ± 1.14) with longest shoot length (2.97 ± 0.18) were obtained directly (without an intervening callus phase) from the leaf explants using a combination of BAP (22.2 μM) and IAA (0.5 μM). BAP used in combination with NAA produced fewer shoots per explant as compared with the use of IAA and the regeneration was mediated by callus formation. For root induction, the elongated shoots were separated and transferred onto MS medium supplemented with indole-3-butyric acid (IBA, 4.9 μM). Rooted plantlets (90%) were successfully transferred to soil in the greenhouse with a 75% survival rate.

The effect of catena position and stump characteristics on the coppice response of three savannah fuelwood species

Fuelwood is still the primary energy source for rural households across the savannah biome of Africa. Coppice growth is an important species-specific trait that strongly influences fuelwood production and regeneration, and yet coppice growth patterns are poorly understood in African savannahs. It is therefore vital that factors affecting coppice growth of species, such as environment conditions and harvesting technique, be better understood in order to develop models for sustainable fuelwood use. This study investigated coppice growth and resource allocation strategies in relation to (1) position along the landscape catena and (2) harvesting technique, for three savannah fuelwood tree species: Dichrostachys cinerea, Albizia harveyi and Combretum collinum. The study was conducted in a dystrophic semi-arid savannah in the far north-east of South Africa. A total of 1146 harvested stumps were sampled in topland and bottomland sites in three locations around a rural village. Stump characteristics (diameter and height) and coppice shoot variables (number of shoots, length and diameter of each shoot, length of longest shoot, and diameter of fattest shoot) were measured for each stump. Three soil samples were taken in each site for physical and chemical analysis. No statistically significant differences were found in soil variables between topland and bottomland sites, probably due to low sample size. Coppice resource allocation strategies varied between species. D. cinerea exhibited a ‘quantity-driven’ strategy, with the production of large numbers of relatively small coppice shoots with high length:diameter ratio (shoot taper function). C. collinum exhibited a ‘quality-driven’ strategy, characterized by the production of a relatively low number of larger coppice shoots. Coppice growth variables for A. harveyi were intermediate between those of the other two species, suggesting a strategy where allocation of resources to the number and growth of shoots is more balanced. However, allocation of resources relative to the size of the cut stem, indexed by total shoot basal area:stump basal area ratio, did not differ significantly between species. Coppice growth was strongly favoured in bottomland sites for D. cinerea, and to a lesser degree, C. collinum. Catenal position had a negligible influence on coppice growth of A. harveyi. Number of shoots produced increased with cutting height for all three species. For all three species the number of shoots increased with stump diameter, and mean shoot size also increased with stump size for D. cinerea. There was a significant negative relationship between stump diameter and total shoot basal area:stump basal area ratio for A. harveyi and C. collinum. A framework for optimizing different coppice growth variables according to species, catenal position and harvesting technique is given.

Aluminum Resistance among Seeded Bermudagrasses

Aluminum toxicity is a major limiting factor for turfgrass establishment and growth when soil pH is <5.0. Limited information on aluminum resistance is available among warm-season turfgrasses and these turfgrasses often grow in the areas with acid soil conditions. The objectives of this study were 1) to evaluate seeded bermudagrass (Cynodon dactylon L.) cultivars for the ability to tolerate a high level of aluminum and 2) to measure the extent of aluminum damage to the root systems. In total, 16 bermudagrass cultivars were evaluated under greenhouse conditions using a solution culture and an acid Tatum soil (Clayey, mixed, thermic, typic, Hapludult). The soil had pH 4.4% and 69% exchangeable aluminum. A concentration of 640 μm aluminum and a pH 4.0 was used for solution culture. The grasses were grown for 28 days in solution culture; 28 days in the acid Tatum soil; and 78 days in the acid Tatum soil before harvesting. Aluminum resistance was determined by measuring the longest root length, the longest shoot length, dry root weight, dry shoot weight, and shoot to root ratio in comparing the control to obtain the relative Al resistance among the cultivars. The results indicate that seeded bermudagrass cultivars differ in their aluminum resistance.

Influence of phenylacetic acid on clonal propagation of Decalepis hamiltonii wight & ARN: An endangered shrub

We have developed a highly efficient two-stage protocol for induction of multiple shoots from single node in vitro shoot tip explants of Decalepis hamiltonii. It was found that phenylacetic acid (PAA) had a synergistic effect on shoot multiplication when treated with N6-benzyladenine (BA). This protocol used PAA for both multiple shoot induction from nodal explants, elongation of primary shoots, and initiation of adventitious shoot formation from primary shoots. Murashige and Skoog medium containing BA (2.22–31.08 μM) and α-naphthaleneacetic acid (0.27–10.74 μM) or PAA (7.34–36.71 μM) was used to initiate shoot formation from nodal explants. The maximum number of shoots per culture was produced on a medium containing 31.08 μM BA and 14.68 μM PAA, while the longest shoot length and nodes were obtained on medium containing 22.2 μM BA and 14.68 μM PAA. Shoots subcultured on MS medium containing 22.2 μM BA and 14.68 μM PAA elongated along with secondary shoot formation. The shoots were rooted on medium containing 9.7 μM indole-3-butyric acid. The plantlets were acclimatized in soil with an 80–90% survival rate under field conditions.

Evaluation of mulberry germplasm based on growth and anatomical parameters

Variability in respect of growth and anatomical parameters were studied in 15 (11 exotic and 4 indigenous) mulberry germplasm accessions. A wide range of variation observed among different accessions both for growth and anatomical parameters. Analysis of variance showed significance at P<0.01 level in all parameters studied. To find out the association, simple correlation was carried out among the different parameters. High significant and positive correlation observed in shoot number per plant, longest shoot length and total shoot length with leaf yield per plant. Single leaf weight showed negative significant correlation with longest shoot length, internodal distance and survival per cent whereas positive significant association with leaf area and moisture per cent. Among anatomical parameters stomatal frequency showed negative significant association with spongy layer thickness and moisture retention capacity. Besides this, all other characters also showed association among themselves.

Etiolation as a pretreatment for in vitro establishment and multiplication of mature chestnut

Localized etiolation of branches in the crown of a 30‐year‐old chestnut tree produced plant material that responded much better to establishment and multiplication in vitro than unetiolated material, whose cultures were very difficult to maintain (response being measured in terms of the percentage of cultures established, the mean number of shoots formed per explant, the number of 8‐mm segments per new shoot, the length of longest shoot in each culture, and the coefficient of multiplication). Only 22% of the initial explants from unetiolated material were successfully established, as against 79% for etiolated material, with similar differences between the coefficients of multiplication of the two lines in successive cultures. Accordingly, partial etiolation of branches is proposed as a suitable pretreatment for in vitro propagation of selected mature trees, when physiologically juvenile materials such as stump sprouts, epicormic shoots or root suckers are not available.