Sugarcane Seedlings Research Articles

RESPON BIBIT BUD SETT TEBU PADA PERKECAMBAHAN DAN PERTUMBUHAN TERHADAP PERLAKUAN LAMA PENYIMPANAN DAN PERENDAMAN ZPT SEBELUM TANAM

Sugarcane problems in germination will effect on growth and the yield that is not optimal. The solution obtained from these problems is plant growth regulators soaking and storage time bud sett seedling before planting. This study used a factorial experimental method with the first factor being storage time consisting of 3 levels, namely 0 days (control), 1 day, and 2 days. The second factor was PGR soaking which consisted of control (without PGR soaking), NAA + IBA, and IAA . The experiment was carried out in a completely randomized design with 3 replications. The results of the observations were analyzed by means of variance at the 5% level and the DMRT test to determine the differences between treatments. The combination of storage time and soaking PGR treatments affected the germination of sugarcane seedlings. Control treatment, NAA+IBA , IAA soaking and 1-day storage,germinated faster than the same treatment and stored for 2 days, even seedling soaked in PGR did not germinate. The NAA+IBA, IAA soaking treatment and 1 day storage had better growth than the same treatment, without storage and 2 days storage.The length of storage and soaking of several PGRs before planting gave the same effect on the age of shoots and the number of shoots.
 
 Key words : Sugarcane bud sett, plant growth regulators soaking, storage time, IAA,IBA, NAA

POTENSI DAN ANALISA BIAYA PENYEDIAAN BIBIT TEBU (Saccharum officinarum L.) UNGGUL SECARA IN VITRO DI PT. GUNUNG MADU PLANTATIONS

<p><em>Sugarcane productivity included cane yield and sugar extracted rate (rendemen) fluctuated annually. The main causes of low sugarcane productivity is quality of planting material with no high sugar extracted rate (sugar rendemen) potential, resistance to pests and diseases, stability production, tolerance to climate changed and early age of harvest. For increasing of the yield productivity and producing a superior sugarcane planting material with competitiveness cost, the vegetative propagation through in vitro culture technique via shoot tip culture was carried out. The objective of this research is to produce a superior sugarcane planting in vitro and analyze the costs required. The research was carried out at the Tissue Culture Laboratory, PT. Gunung Madu Plantations (GMP) in March-May 2021. The research stages started from the preparation of explant source plants, sterilization of explants and tools, manufacture of stock solutions and planting media, subculture, and analysis of the costs needed to provide superior sugarcane seeds. The results showed that the basal swelling of explants, increasing the number of shoots, root elongation, and the method of providing superior sugarcane seeds from apical shoot explants in vitro were relatively more competitive with the price of plantlets per culture tube contained 10 clones costly were Rp. 20,328, compared with conventional propagation methods. with the price of sugar cane seedlings material were Rp 1,603/stem.</em></p>

Rapid Multiplication of Sugarcane Seedlings of PSJT 941 Variety from Tissue Culture Using Ethephon and Paclobutrazol

<p>Indonesia's sugar self-sufficiency was targeted since 2014 but the target has not been reached yet. One of the major constraints is the limited healthy seedlings available for new sugarcane area expansion. The mass production of healthy sugarcane seedlings may be achieved by rapid multiplication of tissue culture-derived seedlings using plant growth regulators (PGR) applied in the nursery house. The aim of this study was to determine the effect of ethephon and pacloburazol (PBZ) on the growth and seedling multiplication of sugarcane PSJT 941 variety. The research was carried out in the nursery house at Pasuruan Experimental Station, Indonesian Sugarcane Research Center. This study was arranged using a randomized block design with three replications. The treatments included (a) 3.5 ml/l ethephon, (b) 7.0 ml/l ethephon, (c) 1.5 ml/l PBZ, (d) 3.0 ml/l PBZ, and (e) control (without application of neither ethephon nor PBZ). The results showed that the highest number of shoots per clump was obtained from 3.0 ml/l PBZ treatment (8.7 shoots/clump) after 3 months of application. In the contrary, PBZ reduced the plant height compared with control and ethephon. Ethephon and PBZ treatments improved seed multiplication 8–52 times, much higher than the control that produced seed multiplication value six times. Further study is necessary to obtain optimal PBZ concentration for better stem height by decreasing the PBZ inhibition effect on stem growth.</p>

Manganese toxicity-induced chlorosis in sugarcane seedlings involves inhibition of chlorophyll biosynthesis

Manganese (Mn) toxicity-induced leaf chlorosis limits crop production in acidic soils, but its underlying mechanisms remain unknown. The effects of excessive Mn on chlorophyll (Chl) biosynthesis in sugarcane (Saccharum officinarum L.) leaves were investigated. Under Mn treatment, Chl concentration decreased with Mn accumulation and chlorosis appeared in expanding leaves. Before that, levels of the initial Chl precursor 5-aminolevulinic acid (ALA) and its downstream intermediates decreased, whereas magnesium-protoporphyrin IX monomethyl ester (MgPME) accumulated. Overaccumulation of Mn in leaves downregulated the ALA biosynthetic gene GluTR (encoding glutamyl-tRNA reductase) and MgPME conversion gene MgPMEC (encoding MgPME cyclase), upregulated the ALA biosynthesis inhibitor FLU (encoding FLUORESCENT), but had no significant effect on the expression of other Chl biosynthetic genes. The above Mn-induced changes of Chl precursors and expression of corresponding genes commenced before the Chl decline and leaf chlorosis, and were reversed by ALA supplementation. Thus, excessive Mn-induced chlorosis in sugarcane is mediated by a Chl-biosynthesis disorder resulting from the inhibition of ALA synthesis and MgPME conversion.

Pengaruh Asam Humat terhadap Karakteristik Morfologi Tebu (Saccharum officinarum L.) Varietas Bululawang

Sugarcane (Saccharum officinarum L.) is a plantation crop that is used as raw material for the consumer sugar and industrial sugar. The need for sugar is increasing every year but is not matched by an increase in sugarcane production due to several factors including cultivation management that is not optimal. Sugarcane production begins with good nursery management, including using genetic of seeds and the right planting media. One alternative to improve the quality of growing media is to use humic acid (HA) as a soil enhancer. This study aims to determinate the effect of giving HA on the morphological characteristics of sugarcane seedlings of Bululawang variety (BL). This research was carried out in an integrated laboratory greenhouse at the Polytechnic LPP Yogyakarta from Maret to July 2021. This study used a non-factorial completely randomized design (CRD) with five treatments and three replications consisting of P0 (control), P1 (25 ml.polybag-1), P2 (50 ml.polybag-1), P3 (75 ml.polybag-1), and P4 (100 ml.polybag-1). The morphological characteristics observed is plants height (cm), number of leaves (strands), stem diameter (mm) and longest root length (cm). the results of the study were analyzed using ANOVA at the 5% level and continued using the Duncan Multiple Range Test (DMRT) at the 5% level. The result showed the effect on morphological characters on all observation variables where the P3 treatment had the best growth and morphological characters, so that in general the additional of HA affected the morphological characteristics of sugarcane seedlings of BL varieties.

Composted Sewage Sludge Application in a Sugarcane Seedling Nursery: Crop Nutritional Status, Productivity, and Technological Quality Implications

Composted sewage sludge (CSS) contains large amounts of organic matter and nutrients and can be used as an organic fertilizer to improve growth, yield, and quality of sugarcane. However, there is a lack of information regarding the impact of CSS application on sugarcane seedling performance in nursery environments. A field study was conducted using a randomized complete block design to evaluate the development, nutritional status, productivity, and technological quality of sugarcane seedlings after CSS application with or without mineral fertilizer. Morphological variables (stem height, diameter, and number, as well as leaf area), technological attributes (total recoverable sugar: ATR; quantity of sucrose in sugarcane juice: Pol; Brix: percentage (weight/weight) of soluble solids contained in juice; TAH: tons of sugar per hectare), nutritional status, and sugarcane productivity were evaluated. Treatments did not influence morphological and technological variables except for TAH but did positively alter nutritional status and seedling productivity. The application rates of 5.0 and 7.5 Mg ha−1 of CSS with or without mineral fertilizers (MF) provided the greatest increase in crop productivity. Our results indicate that CSS can be a sustainable nutritional management option in sugarcane seedling nurseries, resulting in greater crop productivity at lower mineral fertilization rates.

Composted Sewage Sludge Application Reduces Mineral Fertilization Requirements and Improves Soil Fertility in Sugarcane Seedling Nurseries

Sugarcane demands large amounts of nutrients to reach a high level of productivity. Nutrients are generally supplied by mineral fertilizers, but their high costs and negative environmental impacts have generated interest in greater use of organic nutrient sources such as composted sewage sludge (CSS). In this study, we evaluated changes in soil chemical properties after the application of CSS or CSS/mineral fertilizer (MF) combinations to soil containing sugarcane seedlings under nursery conditions. Treatments included: T1: conventional mineral fertilization (MF) without application of CSS, T2: 100% of the recommended MF (06–30–24); T3: application of 2.5 Mg−1 CSS; T4: 5.0 Mg−1 CSS, T5: 7.5 Mg−1 CSS, T6: 2.5 Mg−1 CSS and 50% MF, T7: 5.0 Mg−1 CSS and 50% MF, T8: 7.5 Mg−1 CSS and 50% MF, T9: 2.5 Mg−1 CSS and 100% MF, T10: 5.0 Mg−1 CSS and 100% MF, T11: 7.5 Mg−1 CSS and 100% MF. Soil chemical properties were evaluated from the soil surface (0.0–0.25 m) and subsurface (0.25–0.50 m) horizons. The results showed that the increase in CSS application did not affect soil organic matter content at either depth, while Zn concentrations increased in the soil subsurface horizon. The application of CSS at 5.0 Mg ha−1 with or without 50% MF resulted in the highest pH values, sum of bases, cation-exchange capacity, P, K, Ca, Mg, Cu, and Zn in surface horizons. The use of CSS as an organic fertilizer in sugarcane nurseries improves soil fertility, reduces mineral fertilizer requirements, and, thus, facilitates the sustainable disposal of sewage sludge.

Cloning and functional analysis of <italic>ScGA20ox1</italic> gibberellin oxidase gene in sugarcane

<p id="C3">GA20-oxidase (GA20ox) is a key rate-limiting enzyme in the synthesis of gibberellic acid (GA), but the biological function and expression pattern of gene <italic>GA20ox1 </italic>in sugarcane remain unknown. In this study, we cloned GA20-oxidase gene (<italic>ScGA20ox1</italic>) from the sugarcane variety ROC22 sequence by RT-PCR and RACE, which had a total length of 1574 bp and a complete open reading frame (ORF) of 1125 bp that encoded 375 amino acids. The ScGA20ox1 protein is a hydrophilic protein with a molecular weight of 42.3 kD, an iscelectric point (pI) of 5.95, and no transmembrane structure or signal peptide. Real-time fluorescence quantitative analysis revealed that <italic>ScGA20ox1</italic> had the highest expression levels in stems, medium in the leaves, and the lowest in roots of sugarcane seedlings. Drought stress, low temperature stress, and GA₃ treatment change the expression patterns of <italic>ScGA20ox1</italic> in different tissues. <italic>ScGA20ox1</italic> was transformed into Arabidopsis via Agrobacterium-mediated transformation. Transgenic <italic>Arabidopsis thaliana</italic> plants with overexpressed <italic>ScGA20ox1</italic> were obtained from the transformed <italic>Arabidopsis thaliana via</italic> Agrobacterium-mediated transformation, which showed a phenotypic variation of plant height and internode length increase. In conclusion, <italic>ScGA20ox1</italic> was involved in sugarcane’s growth as a crucial regulator in response to abiotic stress and the phenotypic variation of overexpressed transgenic <italic>Arabidopsis thaliana</italic> changed, which would lay a theoretical basis for future in-depth studies on <italic>ScGA20ox1</italic>’s biological function and analysis of the molecular mechanism of sugarcane plant shape regulation.

The alleviation of manganese toxicity by ammonium in sugarcane is related to pectin content, pectin methyl esterification, and nitric oxide

AbstractCoexistence of ammonium () with manganese (Mn) in acid soils may facilitate the alleviation of Mn toxicity to plants. However, the effect of on Mn toxicity and the corresponding mechanisms are unclear. In this study, the effects of and nitrate () on Mn toxicity, cell wall properties, and nitric oxide (NO) signaling in sugarcane were compared. alleviated Mn‐induced chlorosis in sugarcane seedlings and increased seedling biomass compared with . Exogenous application of decreased the root cell wall pectin content and methyl esterase (PME) activity, but increased the degree of root pectin esterification (PMD). These changes were accompanied by reductions in the Mn content in roots, leaves, root cell wall, and cell wall pectin. An analysis of adsorption kinetic revealed less Mn‐adsorption capacity in cell walls extracted from ‐fed than from ‐fed sugarcane. Mn induced NO accumulation in sugarcane roots, but ‐fed seedlings accumulated less NO. Exogenous application of the NO donor sodium nitroprusside increased the Mn content of root cell wall pectin in ‐fed sugarcane, while the NO scavenger 2‐(4‐carboxyphenyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxid decreased the Mn content in ‐fed sugarcane. These treatments eliminated the difference in the pectin Mn content between ‐fed and ‐fed sugarcane, as did a similar treatment with the nitrate reductase inhibitor tungstate, which decreased root cell wall pectin content and NO accumulation. These results suggest that (i) alleviates Mn toxicity in sugarcane by reducing root pectin accumulation and root cell wall PME activity, thereby increasing cell wall PMD and decreasing both the Mn‐binding capacity of cell wall and Mn accumulation, and (ii) NO mediates the accumulation of both pectin and Mn in response to different forms of nitrogen. The physiological mechanisms underlying the alleviation of ammonium on Mn phytotoxicity were clarified, which provided important implication for agricultural production and ecosystem functioning in acid soil.

Transcriptome Analysis Reveals a Gene Expression Pattern That Contributes to Sugarcane Bud Propagation Induced by Indole-3-Butyric Acid.

Sugarcane is a cash crop that plays an integral part in the sugar industry. The Sustainable Sugarcane Initiative (SSI) has been adopted globally, ensuring enough and aiming for more yield, helping increase disease-free sugarcane cultivation. Single-bud seeds could be the best approach for sugarcane cultivation. Indole-3-butyric acid (IBA) is a rooting agent utilized significantly in seedling propagation. Greenhouse experiment results discovered the significant growth promotion in sugarcane seedlings and accumulation of plant hormones at 100 ppm IBA. Next, we performed transcriptomic analysis of sugarcane buds using RNA sequencing and compared their gene expression during root development due to affect of IBA (100 ppm). A total of 113,475 unigenes were annotated with an average length of 836 bp (N50 = 1,536). The comparative RNA-seq study between the control (CK) and IBA-treated (T) buds showed significant differentially expressed unigenes (494 upregulated and 2086 downregulated). The IBA influenced major biological processes including metabolic process, the cellular process, and single-organism process. For cellular component category, cell, cell part, organelle, membrane, and organelle part were mainly affected. In addition, catalytic activity and binding were primarily affected in the molecular function categories. Furthermore, the expression of genes related to plant hormones and signaling pathways was analyzed by qRT-PCR, which was consistent with the RNA-seq expression profile. This study provides new insights into the IBA response to the bud sprouting in sugarcane based on RNA sequencing, and generated information could help further research on breeding improvement of sugarcane.

Weed interference periods in pre-sprouted sugarcane seedlings

The aim of this study was to determine the period prior to interference (PPI), the critical-period of interference prevention (CPIP), and the total-period of interference prevention (TPIP) in sugarcane in the pre-sprouted seedlings (PSS) system, in coexistence with Cyperus rotundus and other weeds, adopting a loss of 5% in yield. The treatments corresponded to seven coexistence periods and seven weed control periods: 0–30, 0–60, 0–90, 0–120, 0–150, 0–180, and 0–240 days after planting (DAP). The cultivar used was IACSP95-5000. Until 26 DAP, weeds did not compete with sugarcane. From 26 to 68 DAP, weeds competed with sugarcane. Thus, it is considered that from 68 DAP, weed control is no longer necessary because increased periods of control do not result in significant yield gains. The results showed a 26 days PPI, 26–68 days CPIP, and 68 days TPIP, adopting a loss of 5% in yield, for weed competition with sugarcane in the PSS system. There was a reduction of 8.22% in sugarcane yield per day of coexistence and an increase of 11.37% per day of control.

Micrometeorological Modification Promoted by Photoselective Meshes and Supplementary Lighting in the Production of Pre-sprouted Sugarcane Seedlings

Micrometeorological Modification Promoted by Photoselective Meshes and Supplementary Lighting in the Production of Pre-sprouted Sugarcane Seedlings

ScMT10, a metallothionein-like gene from sugarcane, enhances freezing tolerance in Nicotiana tabacum transgenic plants

Sugarcane (Saccharum spp. hybrid) is of tropical origin, yet generally cultivated in subtropical areas. Cold stress is a major environmental factor that impairs the production of sugarcane in that area. Metallothioneins, a family of small, cysteine-rich proteins, are proved to be involved in metal homeostasis and detoxification and thus alleviate stress-induced ROS accumulation. Here, a cDNA clone deducing a single Cys-rich domain type 2 metallothionein-like protein, designated ScMT10, was isolated from sugarcane. The level of ScMT10 expression was up-regulated by salicylic acid (SA), cold, and oxidative stress (H2O2) in sugarcane seedlings, but it was down-regulated in response to abscisic acid (ABA), methyl jasmonate (MeJA), heavy metal ions (Cu2+, Cd2+), and salinity. Transgenic tobacco (Nicotiana tabacum) plants (ScMT10-OE) showed a remarkable enhancement in freezing tolerance compared with wild-type plants (WT). Furthermore, ScMT10-OE tobacco showed a lower electrolyte leakage, reduced malondialdehyde contents, and slower ROS (including H2O2) accumulation under freezing stress and retained higher proline, soluble sugar, and relative chlorophyll content compared to WT plants. The expression profiles of ScMT10 in the transgenic tobacco were similar to those in sugarcane seedlings under different stresses. Besides, the level of H2O2 in the ScMT10-OE plants was comparable to that observed in WT plants under heavy metal, salt, and drought stress. Therefore, the transgenic plants did not perform better than WT plants under those stresses. Taken together, we present a hypothesis that ScMT10 was exclusively and positively involved in the cold stress-induced accumulation of reactive oxygen species (ROS). The over-expression of ScMT10 in tobacco decreased the contents of endogenous ROS, MDA, and relative electric conductivity. It increased the accumulation of proline, soluble sugar, and relative chlorophyll under freezing stress, which alleviated the oxidative damage to the cell membrane during freezing exposure. ScMT10 can be considered as a candidate gene for cold-tolerance trait improvement.

Functional Investigation of Plant Growth Promoting Rhizobacterial Communities in Sugarcane.

Plant microbiota are of great importance for host nutrition and health. As a C4 plant species with a high carbon fixation capacity, sugarcane also associates with beneficial microbes, though mechanisms underlying sugarcane root-associated community development remain unclear. Here, we identify microbes that are specifically enriched around sugarcane roots and report results of functional testing of potentially beneficial microbes propagating with sugarcane plants. First, we analyzed recruitment of microbes through analysis of 16S rDNA enrichment in greenhouse cultured sugarcane seedlings growing in field soil. Then, plant-associated microbes were isolated and assayed for beneficial activity, first in greenhouse experiments, followed by field trials for selected microbial strains. The promising beneficial microbe SRB-109, which quickly colonized both roots and shoots of sugarcane plants, significantly promoted sugarcane growth in field trials, nitrogen and potassium acquisition increasing by 35.68 and 28.35%, respectively. Taken together, this report demonstrates successful identification and utilization of beneficial plant-associated microbes in sugarcane production. Further development might facilitate incorporation of such growth-promoting microbial applications in large-scale sugarcane production, which may not only increase yields but also reduce fertilizer costs and runoff.

Biochar as an alternative substrate for the production of sugarcane seedlings

ABSTRACT Biochar, which has emerged as an important form of the transformation and final disposal of biomass, can be used directly in soil or in seedling nurseries. In this study, the use of biochar of different particle sizes and percentages was evaluated in replacement to a conventional substrate used in the production of sugarcane seedlings. To this end, an experiment was carried out based on a completely randomized design, with a 5 × 4 factorial scheme, consisting of five different percentages of biochar (with 0, 25, 50, 75, and 100% v/v substitution of the conventional substrate) and four particle sizes (&lt;1, 2, 4, and 9 mm), with nine repetitions. As seedling growth variables, the average sprouting time, sprouting speed index, plant height, leaf number, leaf length, and width + 2, as well as the dry mass of the aerial parts and roots were evaluated. Irrespective of the percentage of commercial substrate replaced with biochar, sprouting time was found to be shorter when 6-mm-diameter biochar particles were used. With respect to the sprouting speed index, it was found that regardless of particle size, the highest value occurred when biochar was used to replace 42% of the commercial substrate. The substitution of the commercial substrate with biochar had the effect of reducing the growth of sugarcane seedlings.

Integrasi Pembibitan Tanaman Tebu Tunas Tunggal dan Budi Daya Ikan Lele

This study evaluates the feasibility of integration of the single-bud sugarcane and catfish farming system and the growth rate of both plants and fish. The observation started from September to November 2020. The design used was randomized with one factor. The treatments used were cultivation of single-bud sugarcane in polybags, hydroponic single-bud sugarcane cultivation, integration of single-bud sugarcane-catfish, and catfish cultivation. The results showed that the growth of sugarcane seedlings and the catfish indicate that the integrated cultivation system of sugarcane-catfish is feasible to apply. Such an integration system produces a better number of leaves, stem diameter, leaf area, and root length than the cultivation system of sugarcane seedlings in polybags. The weight of the canopy and the root of sugarcane seedlings in the integration system is also noticeable greater than the sugarcane seedlings cultivated in the polybag. In addition, the rate of catfish growth in the integration system is better than catfish's ordinary cultivation.&#x0D; &#x0D; Keywords: hydroponic, integration farming system, single bud sugarcane planting

Chemical management of Cyperus rotundus L. and other weeds at sugarcane in PSS system

Among the main weeds with difficult to control in the sugarcane fields can be cited purple nutsedge (Cyperus rotundus L.). This specie was observed in the seed bank in sugarcane fields harvested with or without burning. The objective of this study was to evaluate the efficacy of herbicides in pre-sprouted seedlings (PSS) of sugarcane in the control of C. rotundus and other weeds. The work was carried out in the field, in a randomized complete block design, and four replications. The treatments corresponded to the herbicides applied in pre-planting: sulfentrazone (800 g a.i. ha-1), diclosulam (193.17 g a.i. ha-1), imazapic (133 g a.i. ha-1) and imazapyr (500 g a.e. ha-1); post-planting: halosulfuron (112.5 g a.i. ha-1), ethoxysulfuron (135 g a.i. ha-1), MSMA (1,975 g a.i. ha-1) and 2,4-D (1,340 g a.e. ha-1); besides a control treatment weeding and another without weeding. The symptoms of injury on sugarcane plants, percentage of weed control, variables related to agronomic performance of sugarcane, and yield were evaluated. The herbicides diclosulam, imazapic, and imazapyr caused serious damage to the crop. The halosulfuron, ethoxysulfuron, MSMA, and 2,4-D did not cause symptoms of injury to sugarcane, however, the treatments had a reduced yield due to the low weed control. The sulfentrazone treatment obtained the second highest yield but with effective weed control (&gt;70%) up to 45 days after planting. The best controls were obtained with pre-planting treatments; however, herbicide positioning studies should be performed in relation to PSS.

Azospirillum Brasilense Application in Pre-Sprouted Seedlings (PSS) of Sugarcane

The use of sugarcane pre-sprouted seedlings (PSS) of high quality is a key factor for success of sugarcane production system in Brazil, and the use of plant growth-promoting bacteria (PGPB) can be decisive in obtaining high-quality seedlings. However, it is not known which rate of inoculant containing Azospirillum brasilense should be used. Thus, this study was conducted to evaluate the efficiency of Azospirillum brasilense inoculation and establish the optimal rate of inoculant application on the development of sugarcane PSS (Saccharum officinarum). Pre-sprouted seedlings from commercial hybrids IACSP95-5000, RB855035, RB855536, and RB867515, produced from individual buds (mini-sets) of 3.0 cm were transplanted at 12 days after sprouting into 290 mL tubes. Treatments were arranged in completely randomized design, in 4 × 5 factorial scheme: four genotypes (IACSP95-5000, RB867515, RB855035 and RB855536) and five rates of commercial inoculant AzoTotal®, containing the strains AbV5 and AbV6 [0 (control); 0.5; 1.0; 2.0 and 4.0 mL per tube], four replicates. The inoculant rates increased the plant height, shoot dry matter, root dry matter, total dry matter, height: diameter ratio, and Dickson quality index of PSS of the genotypes IACSP95-5000, RB855035 and RB867515, as well as an increase in number of leaves and stalk diameter of RB855035 and RB867515. The genotype RB855536 has no response to application of inoculant containing A. brasilense during the production phase of pre- sprouted seedlings. The optimal application rate of inoculant containing A. brasilense for production of high-quality pre-sprouted sugarcane seedlings varies between 2 and 3 mL of inoculant per seedling. Keywords: Saccharum officinarum. Diazotrophic bacteria. Nitrogen. Inoculation. Resumo O uso de mudas pré-brotadas (MPB) de cana-de-açúcar (Saccharum officinarum) de qualidade é fator chave para sucesso da produção de cana-de-açúcar no Brasil e o uso de bactérias promotoras de crescimento de plantas pode ser determinante na obtenção de mudas de qualidade. Entretanto, não se tem conhecimento da dose ideal de inoculante contendo Azospirillum brasilense. Este estudo foi conduzido com o objetivo de avaliar a eficiência da inoculação de Azospirillum brasilense e estabelecer a dose ideal no desenvolvimento de MPB de cana-de-açúcar. MPB de quatro variedades de cana-de-açúcar, oriundas de minirrebolos de 3,0 cm foram transplantadas aos 12 dias após a brotação para tubetes de 290 mL. Os tratamentos foram dispostos em delineamento casualizado, esquema fatorial 4 × 5: quatro variedades (IACSP95-5000, RB867515, RB855035 e RB855536) e cinco doses do inoculante comercial AzoTotal®, contendo as estirpes AbV5 e AbV6 [0 (controle); 0,5; 1,0; 2,0 e 4,0 mL por tubetes], com quatro repetições. As doses de inoculantes resultaram no aumento da altura das plantas, matéria seca da parte aérea, matéria seca das raízes, matéria seca total, relação altura: diâmetro e no índice de qualidade de Dickson das MPB das variedades IACSP95-5000, RB855035 e RB867515, além de resultar no aumento do número de folhas e diâmetro do colmo das variedades RB855035 e RB867515. A variedade RB855536 não responde à aplicação de inoculante durante a fase de produção de MPB. A dose ótima do inoculante para na produção de MPB de qualidade pode variar entre 2 e 3 mL de inoculante por muda. Palavras-chave: Saccharum officinarum. Bactérias diazotróficas. Nitrogênio. Inoculação.

DEVELOPMENT OF A MACHINE FOR CUTTING SUGAR CANE BUDS

This research aims to manufacture and test a machine for cutting sugar cane buds to develop mechanization of the stage of preparing sugarcane seedlings in the nursery. The developed machine consists of a frame, cutting unite, electric motor, and power transmission system. This machine will save the time, effort and costs spent on cutting reeds by traditional methods at farmers. The machine cuts the sugarcane stalks that are used as seeds and which contain undamaged buds, the operator cuts the groups of sprouts by the bud cutting machine. The machine has been tested at three transmission ratios to cutting rate of R1 = 22, R2 = 32, and R3 = 40 buds/min. The results of preliminary tests revealed that the machine achieved the skipping, percentage of damaged, cutting efficiency, and productivity was (4.09, 7.19, 11%), (2.37, 5.39, and 8.99%), (97.63, 94.61, 91%), (1266, 1782, 2136 bud/hr.) at the cutting rate R1, R2, and R3 respectively. The total costs for operating the machine are 50.3 L.E./h to at the highest cutting rate R3.

Optimizing selection indices in sugarcane seedlings

AbstractSelection of superior clones in sugarcane (Saccharum spp.) breeding programs follows a multistage process, starting in the first stage with selection of seedlings grown from seeds obtained from crosses. Effective selection of seedlings is important but notoriously difficult. Selection validity is affected by experimental error variation and interplant competition effects and is also complicated by the need to consider many different traits that affect economic value of cultivars (e.g., cane yield, sugar content, fiber content, disease resistance, etc.). In this study, we developed an optimized protocol for selection of sugarcane seedlings that balances the desire to maximize genetic gains but also be cost and labor efficient. A population of seedlings in commercial sugarcane breeding programs was first evaluated in a field trial (Stage 1). A subset of the population was then taken at random and grown in a subsequent trial (Stage 2) for evaluation in small plots. Minor modifications to application of the complete selection index that would greatly reduce labor requirements but have only a small impact on reducing genetic gains were then explored, to identify optimal selection protocols for routine application in commercial breeding programs. A procedure is recommended for routine selection of seedlings that involves (a) selection of families based on an index of four traits (stalk diameter, stalk height, trashiness, and pith rating, all derived from measurements of a small sample of seedlings in each family), followed by (b) sequential measurement and culling of individual seedlings in each selected family based on (in order) trashiness, stalk diameter, and pith rating.