Late Maturing Cultivars Research Articles

Potato Stem Density Effects on Canopy Development and Production

Controlled environment studies with potato frequently assume responses from single-stem potato plants can be extrapolated to the field where multiple-stemmed plants are common. Controlled environment studies were conducted to characterize differences in canopy growth, development, and dry matter production between single- and multiple-stemmed potted potatoes. Leaf area distribution was influenced by stem density, with main stem and apical lateral branch leaf area being 150% to 200% larger in triple-stemmed (3S) versus single-stemmed (1S) pots (P < 0.01), while basal lateral branch leaf area was 50% less (P < 0.01). Basal lateral branches were more developed in 1S pots with longer branch lengths, more leaf area, and higher orders of branching. In a second experiment, more leaves were initiated in higher-density pots; however, individual leaf areas were approximately 50% smaller than those in 1S pots. Total leaf area and total, vegetative, and tuber dry matter production were unaffected by stem density in either experiment on a per pot basis. Development and growth of lower basal lateral branches in the 1S potato canopy offset any initial advantage in leaf numbers in the multiple-stemmed plants. These results appeared to validate the assumption that, given a late maturing cultivar and adequate nutrition, responses from single-stemmed plants can be extended to multiple-stemmed plants when expressed on a production area basis. These findings have practical considerations for potato researchers who conduct growth chamber experiments and potato modelers.

Optimal timing of fungicide applications for the control of Podosphaera leucotricha, the causal agent of peach rusty spot in Serbia

Peach rusty spot has regularly occurred in Serbia in recent years, causing significant economic losses in the production of late maturing cultivars (Summerset, Suncrest, Fayette and O?Henry). Concerns regarding the etiology of this disease have been solved using molecular identification and cross-pathogenicity tests, which have proved that peach rusty spot is caused by Podosphaera leucotricha. The usual recommended strategy for its control, by multiple treatments starting from petal fall phenophase, has not proved satisfactory in agro-ecological conditions in Serbia. After testing the fungicide efficacy, a three-year study was carried out to determine the precise treatment terms and make the control of P. leucotricha more efficient. The investigation was conducted in the conditions of natural infection in a Summerset cultivar orchard at the locality of Bela Crkva, during the period 2006-2008. Nine different variants of both single and mixed treatments were tested, covering six defined peach growth phenophases - from green top, until the phenophase of second fruit falling. In the conditions of high levels of natural infection in the control plots, in all three investigation years the most efficient was the variant in which kresoxim-methyl was applied three times: in green top, pink bud and full bloom phenophases (91.69 - 91.92%), followed by the variant of treatments in the phenophases of rose bud, full bloom and petal fall (86.3-87.87%) and the variant of two treatments, performed in the phenophases of pink bud and full bloom (79.3-83.09%). The other tested variants showed significantly lower efficiency. The results obtained could significantly contribute to better peach fruit production, without losses caused by peach rusty spot which is commercially very important disease in Serbia.

A deep-coverage BAC library for Ponkan mandarin and its further use in screening ethylene regulated genes

A deep-coverage bacterial artificial chromosome (BAC) library of Yanxiwanlu Ponkan, a late maturing cultivar, was constructed and evaluated. Results showed that the library contained a total of 61,000 clones. Restriction analysis indicated that the DNA insert sizes ranged from 30 to 170 kb with an average of ∼82 kb. No empty clone was found. Therefore, the library should cover ∼13.6-fold of the citrus genome. Continuous sub-cultivation of 5 randomly chosen clones for up to 100 generations showed no detectable change in their restriction profiles. To demonstrate the application of the library in discovery of genes, 7 ethylene-regulated genes were screened by PCR amplification from hierarchically pooled library clones with gene-specific primers. Five positive clones, each representing a different gene, were thus identified from 3840 clones. Sequencing of the clones showed that all of them matched the expected genes, indicating that the library was highly representative.

Estimating the contribution of nitrogen from legume cover crops to the nitrogen nutrition of grapevines using a 15N dilution technique

Cover cropping is increasingly being used as a form of sustainable soil management in grapevine (Vitis vinifera L.) production. The objective of the current study was to determine the effect of a legume cover crop on a set of growth and production variables of a vineyard, and to quantify the relative importance of legume nitrogen (N) as a source of N for the vine plants and to compare this to the current recommended practice of annually applying 40 kg fertilizer-N ha-1. The study was carried out in a 5-yr-old vineyard cv. Cabernet Sauvignon at the Cauquenes-INIA Experimental Center in one of the wine production areas of Chile. The treatments were: control without cover crop (C); a legume mixture of early maturing cultivars of subterranean clover (Trifolium subterraneum L.) and burr medic (Medicago polymorpha L.) (EMC); or a legume mixture of late maturing cultivar of subterranean clover and balansa clover (T. michelianum Savi) (LMC). Average inputs of legume N generated by the EMC and LMC treatments represented 112 and 161 kg above-ground legume N ha-1yr-1, respectively. Grape dry matter production was increased significantly (P ≤ 0.05) by 48–61% and the amount of N accumulated in grape bunches was enhanced by 74–105% after 2 years of legume cover crop. However, no significant (P > 0.05) effects of cover cropping were observed on vine leaf, canes, roots or trunk biomass. To estimate the relative contribution of legume and fertilizer N to the N nutrition of grapevines 15N-enriched fertilizer (10 atom% 15N excess) was applied to the soil in micro-plots within all treatments as two split applications of 20 kg N ha-1. The 15N composition of vines grown with or without cover crops were subsequently compared. Any measured reduction in the 15N enrichment of the tissues of cover cropped vines relative to the nil cover crop control was assumed to have resulted from the uptake of legume N. Recovery of 15N in vine plant parts was used to calculate the efficiency of use of fertilizer N. Surprisingly the 15N data indicated that the fruit had the lowest reliance upon legume N for growth (only 7–13% cf 14–56% of the N in other organs), even though grape bunches were the only plant part to positively respond to the cover cropping treatments. This suggested that either the temporal patterns of N mineralization in soil and N uptake by vines over the growing season was such that much of the mineral N utilized during fruit development was not directly derived from legume residues, or that N remobilized from other plant parts within the vines was the major source of N for grape production rather than N newly assimilated from soil. The amount of legume N estimated to be recovered by cover cropped vine plants (12–15 kg N ha-1), was similar to the calculated contribution from 40 kg of fertilizer-N applied to vines (11-12 kg ha-1). This amount of N represented <10% of the amounts of N annually returned to the soil in above-ground legume material in the case of the cover cropping treatments, and was equivalent to a recovery of 27–30% of the N applied in fertilizer.

Impact of Developmental Maturity of Soybean on the Seasonal Abundance of Soybean Aphid (Hemiptera: Aphididae)

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), alternates between a primary overwintering host (buckthorn, Rhamnus sp.) and a secondary summer host (soybean, Glycine max). Selection of soybean cultivars with different maturity groups may provide growers with a management tool for A. glycines, either directly through its effect on summer populations that cause economic damage or indirectly through its effect on the production of migrants that disperse to the primary host in fall. This study investigated the abundance and seasonality of A. glycines on soybean cultivars with different maturity rates in central Indiana. The abscission of soybean foliage occurred earlier for early maturing than late maturing cultivars, but no other consistent difference in development or yield was detected among the cultivars tested in this study. The abundance of aphids did not vary consistently among cultivars when soybean was most susceptible to economic damage. A laboratory assay evaluating the larviposition preference of A. glycines alate females, combined with a 7-yr survey documenting the colonization of buckthorn by winged aphids, indicated that the production of gynoparae on soybean began in mid-September and continued until leaf abscission. The abundance of aphids during this period was higher on late maturing cultivars than on early maturing cultivars in both 2006 and 2008, whereas no significant effect was detected in 2007. Altogether, these results suggest that planting early maturing soybean cultivars has little effect on damage by aphids on the current season crop but may reduce the number of fall migrants to the primary host.

Risk assessment for volunteer and seedling GM potatoes in the northernmost European growing areas

Commercial production of genetically modified (GM) potatoes (Solanum tuberosum L.) could represent a risk to conventional production if volunteer plants develop from tubers or true seeds that survive until the following growing season. We studied such risks under northernmost European conditions and monitored the effects of cultivar, tuber size and tuber depth in the soil on winter survival at MTT Agrifood Research Finland, Jokioinen (61°06′N, 23°02′E) from 2004–2007. Tubers of two non-GM cultivars, Saturna and Asterix, and two size classes, 25–30 mm and 45–50 mm, were planted at depths of 10 and 20 cm in autumn, soon after harvest. In winters 2004–2005 and 2005–2006 all tubers planted in the soil in autumn were killed by frost. In 2005–2006, the field was covered by up to 30–40 cm of snow and the minimum soil temperatures ranged between −0.4oC and −0.9oC, but only 0.0–3.5% of the tubers survived and there was no difference between cultivars, tuber sizes and planting depths. Under laboratory conditions compared with −2.0°C and −2.5°C, treatment at −3.0°C for 72 h resulted in significantly lower survival rate of the tubers (8.2%). Asterix, a late maturing table potato cultivar, was more resistant to low temperatures than the processing cultivar Saturna. In general, volunteer tubers are not currently a significant risk for coexistence of GM and conventional potato production in northern Europe due to the cold winter conditions but also due to possibilities to control the sporadic volunteers from the next crop. However, we noted that seedlings initiated from true potato seed are able to produce tubers despite the short growing season. Such a risk could be reduced by accepting only non-berry-producing GM cultivars for cultivation.

Effect of intercropping summer and spring maize on photosynthesisand yield of summer maize

Three cultivars of maize (the early maturity cultivar of "Luyuandan14", the medium maturity cultivar of "Yedan22" and the late maturity cultivar of "Yedan13") were selected to study the effect of maize cultivars on the photosynthetic characteristics and yield of summer maize intercropped with spring maize and monocropped one. The results show that late maturity spring maize cultivar reduces leaf area, light interception rate, chlorophyll content, nitrate reductase activity, and the rate of photosynthesis of summer maize after anthesis under intercropping. To further analyze the relationship between photosynthetic characteristics and the yield of summer maize, the concept of "photosynthetic productivity product (PPP)" was developed. PPP is the product of two or more factors including photosynthetic leaf area, photosynthetic capacity and photosynthetic duration. Compared with single photosynthetic character, PPP is more significantly correlated with yield. Furthermore, the arithmetic product of leaf area, ear leaf chlorophyll contentand days after anthesis, and that of leaf area, photosynthetic rate of ear leaf and days after anthesis are more closely related to yield than the arithmetic product of leaf area and days after anthesis. In conclusion therefore, the differences in yield under different cropping systems are the common actions of photosynthetic leaf area, capacity and duration. Thus medium maturity cultivars of spring maize and late maturity cultivars of summer maize are beneficial to total yield under intercropping. PPP provides a new and efficient analytical dimension for yield and quality superiority in intercropping.

Soybean Seed Yield Performances under Different Cultural Practices

This study was carried out to investigate the yield response of 2 soybean (Glycine max (L.) Merrill) cultivars to different planting dates and plant populations and to examine the relationships of seed yield with leaf area index (LAI) and total dry matter (TDM) during the vegetative and reproductive periods for planting dates, plant populations, and cultivars. Two soybean cultivars, A-3127 (early maturity group, MG-III) and 1530 (late maturity group, MG-IV), were planted in 2 planting dates; mid-April and mid-May during 2005 and 2006 at high (660,000 plant ha^{-1}) and low (330,000 plant ha^{-1}) plant populations. Plantings in mid-April increased seed yield by about 10.0%-13.5% compared with mid-May plantings. High plant populations produced 17.7% higher seed yield than the low population. Seed yield of the late maturity cultivar was more than that of the early maturing cultivar. Significant and positive relationships between seed yield and LAI were evident for planting dates at all growth stages in 2005 and 2006. Seed yields at high and low plant populations were negatively and significantly correlated with LAI at vegetative stage (V_5), but positively and closely related to LAI at reproductive stages (R_4 and R_6) in both experimental years. The relationships between seed yield and LAI with early and late maturity cultivars were significant and positive at all growth stages except the V_5 growth stage in both 2005 and 2006. Seed yield was positively and significantly correlated with TDM at all growth stages for planting dates, plant populations, and cultivars.

Analysis of genetic diversity among Indian niger [Guizotia abyssinica (L. f.) Cass.] cultivars based on randomly amplified polymorphic DNA markers

Randomly amplified polymorphic DNA (RAPD) markers were used to estimate genetic diversity among 18 cultivars of niger from India. Total genomic DNA was extracted and subjected to RAPD analysis using 80 arbitrary 10-mer primers; 17 primers were selected, which yielded a total of 124 bands, 41.20% of them polymorphic. None of the primers produced unique banding pattern for each cultivar. RAPD data were used to calculate a Squared-Euclidean Distance matrix which revealed a minimum genetic distance between cultivars JNC-6 and N-48 and a maximum distance between IGP-76 and JN-30. Based on the distance matrix, a cluster analysis was done using a minimum variance algorithm. The dendrogram generated, based on Ward's method, grouped 18 niger cultivars into two major clusters. The first cluster consisted of early maturing cultivars ( e.g. N-129 and N-134; 80-90 days), and the second of late maturing cultivars ( e.g. GA-8 and GA-9; 135-145 days). The present study shows that there is high diversity among the niger cultivars tested and indicates the potential of RAPD markers for identification and maintenance of niger germplasm for crop improvement purposes.

Determination of Cultivar Coefficients for the CSM-CROPGRO-Peanut Model Using Variety Trial Data

Detailed growth analysis and developmental data are normally required for calibration of crop simulation models in order to determine the cultivar coefficients that correspond to the unique characteristics of each crop and cultivar. The objective of this study was to evaluate the suitability of using variety trial data in which no phenology data were collected for estimating the cultivar coefficients for the CSM-CROPGRO-Peanut model. We selected three peanut cultivars of different maturity, which are commonly grown cultivars in the southeastern U.S. The cultivars were an early maturity cultivar (Virugard), a medium maturity cultivar (Georgia Green), and a late maturity cultivar (C-99R). The variety trial data for these cultivars were obtained from the research reports on variety performance tests conducted in three locations in Georgia from 1994 to 2001. A similar cultivar in the same maturity group was used as a starting point from which to calibrate each of the cultivars. Synthetic cultivars with corresponding values for the different combinations of the selected cultivar coefficients were created for the CSM-CROPGRO-Peanut model; the model was then run for each of these cultivars. The set of coefficients for the synthetic cultivar that produced the lowest root mean square error (RMSE) between simulated and observed yield from the variety trials was adopted as the final values for the candidate cultivar. The accuracy of the cultivar coefficients was evaluated using data on plant growth, development, and yield that were collected during the 2005 growing season in a research station and two farmers' fields in southwest Georgia. Our results demonstrated that variety trial data in which no phenology data have been collected could be used successfully to derive cultivar coefficients for the CSM-CROPGRO-Peanut model. Simulated values of various development and growth parameters were in good agreement with their corresponding observed values for almost all parameters that were evaluated. At final harvest, the RMSE between observed and simulated yield components was 259 kg ha-1 for seed yield, 301 kg ha-1 for pod yield, and 608 kg ha-1 for aboveground biomass. The calibration procedure described in this article could facilitate the estimation of cultivar coefficients for new peanut cultivars if local variety trial data are available.

POTATO CULTIVARS SUSCEPTIBILITY TO POTATO LATE BLIGHT (PHYTOPTHTORA INFESTANS)

The main aim of this research was to determine the susceptibility of Lithuanian selection potato cultivars to late blight. Late blight infection was different in potato groups with various maturities. In early potatoes disease spread was more intensive, and slower in late maturity cultivars. The intensity of potato blight spread in various maturity potato cultivars depends not only on their earliness, but their biologic traits as well. Late blight research has been conducted in the potato breeding program - for the creation of biological-mathematical prognosis models of late blight. Potato cultivar 'Aista' has high resistance to P. infestans . 'Aista' is recommended for growing on ecologic farms.

Influence of Md-ACS1 allelotype and harvest season within an apple germplasm collection on fruit softening during cold air storage

Previous studies have demonstrated a relationship between Md-ACS1 allelotype and apple fruit softening at ambient temperatures. The present study was undertaken to further examine the influence of this allelotype ( -1/1, -1/2 or -2/2) and its interaction with harvest season (early or late) on changes in internal ethylene concentrations (IEC) and fruit softening during cold air storage. This was carried out by describing natural differences found among old apple cultivars/species and modern commercial cultivars. For late maturing cultivars, Md-ACS1-1/1 was firmer at harvest than Md-ACS1-2/2 with the heterozygote intermediate. However harvest firmness showed no differences among for the early season Md-ACS1 allelotypes. The Md-ACS1-2/2 allelotype had a slower rate of postharvest IEC increase and flesh softening compared with Md-ACS1-1/1 and -1/2 allelotypes, and late maturing cultivars had a slower rate of fruit softening than early maturing cultivars, which was independent of postharvest IEC. All three late season allelotypes and early season Md-ACS1-2/2 were firmer after storage than early season Md-ACS1-1/1 and -1/2 allelotypes, reflecting differences in both harvest firmness and softening rates . While cultivar variation in final firmness could be explained partially through Md-ACS1-mediated postharvest ethylene increases and subsequent softening, much more variation was accounted for by their differences in harvest firmness. These results are discussed in relation to strategies for breeding cultivars with superior flesh textures that are maintained during storage.

Forage Production and Nutritive Value of Oat in Autumn and Early Summer

Oat (Avena sativa L.) grown for forage in the northern USA usually is sown in spring and harvested in early summer, with rapid decline in quality after boot stage. This study was conducted to determine if there are differences in forage yield and forage quality between summer sown–autumn harvested and spring sown–early summer harvested oat, and to determine whether seasonal effect is similar among oat cultivars that vary in maturity classification. Oat was sown in summer 2001 and spring 2002 at two locations in Wisconsin and harvested in autumn and early summer, respectively. Oat sown in August produced 6.7 Mg ha−1 of forage when harvested 77 d later, about 1.0 Mg ha−1 less than that obtained from spring sown oat harvested 77 d after sowing. Autumn forage yield was similar among oat cultivars due to decreasing daylength and temperature. Maturation of summer‐sown oat was delayed, resulting in 10 to 15% less neutral detergent fiber (NDF), 18% greater digestibility, and 250% greater water soluble carbohydrate (WSC) concentration than spring‐sown oat. High WSC levels are of particular importance since oat forage harvested in autumn will likely be stored as silage due to poor drying conditions in autumn. Differences in forage quality among cultivars and between spring and autumn oat forage are associated with maturity differences. Oat sown in late summer, and especially the leafy, late maturing cultivar ForagePlus, can supplement high quality forage production in autumn.

The impact of cell division and cell enlargement on the evolution of fruit size in Pyrus pyrifolia.

Dramatic increases in fruit size have accompanied the domestication of Pyrus pyrifolia. To evaluate the contribution of cell division and cell enlargement in the evolution of fruit size, the following study was conducted. Three wild Pyrus and 46 cultivated Pyrus pyrifolia cultivars were selected to examine cell number/size at time of pollination and at time of fruit harvest. The period of cell division was estimated by logarithmic curve of the increasing pattern of cell number, and its correlations with maturation period and final fruit size were analysed. Final fruit size is directly related to the number of cells produced in the period immediately following pollination. Late-maturing cultivars are larger than earlier-maturing cultivars and this is due to an extended period of cell division. The evolution of fruit size in P. pyrifolia has mainly resulted from shifts in the ability of cells to divide rather than to enlarge.

Avaliação da tolerância de cultivares de soja à ferrugem asiática no oeste da Bahia

A utilização de tolerância como forma de controle da ferrugem da soja (Glycine max), causada pelo fungo Phakopsora pachyrhizi, pode ser uma alternativa viável, visto que a resistência qualitativa tem-se mostrado instável, em função da variabilidade do fungo. Este trabalho foi realizado na região oeste da Bahia, na safra 2003/04, com objetivo de avaliar a tolerância das principais cultivares de soja utilizadas na região. Foram avaliadas quatro cultivares de ciclo precoce [MG/BR 46 (Conquista), Emgopa 315, BRS Corisco e M-SOY 8411] e quatro cultivares de ciclo tardio (BRS Barreiras, M-SOY 9350, FT 106 e BRS Sambaíba). A tolerância foi quantificada pela diferença de produtividade entre subparcelas tratadas e não tratadas com fungicida. As cultivares MG/BR 46 (Conquista) e M-SOY 8411 apresentaram diferenças de rendimento não significativas, no entanto, essa característica não pôde ser atribuída à tolerância, em função da baixa severidade observada no ensaio. Essa diferença pôde ser atribuída a escape, uma vez que, no momento em que a ferrugem obteve valores mais elevados de severidade, as duas cultivares já estavam na fase final de desenvolvimento. Embora a severidade máxima observada no ensaio tenha sido baixa (30,5% para a cultivar BRS Barreiras), com exceção das cultivares MG/BR 46 (Conquista) e M-SOY 8411, as demais cultivares avaliadas apresentaram diferença significativa entre as subparcelas tratadas e não tratadas com fungicida, mostrando ausência de tolerância das principais cultivares comerciais cultivadas no oeste da Bahia. Neste trabalho, foi observado que as cultivares de ciclo precoce apresentaram reduções de produtividade inferiores às de ciclo tardio.

Tolerância à interferência de plantas competidoras e habilidade de supressão por cultivares de soja: I. Resposta de variáveis de crescimento

Características morfofisiológicas diferenciais de plantas podem influenciar as relações de competição entre cultura e plantas daninhas. O objetivo do presente trabalho foi avaliar a influência das características de plantas de quatro cultivares de soja sob competição ou não com outros dois cultivares de soja, simulando espécies daninhas dicotiledôneas, durante a fase vegetativa de crescimento. Para isso, conduziram-se dois experimentos: um em vasos, visando fornecer subsídios quanto ao crescimento inicial das plantas de soja; e outro em campo, a fim de acompanhar características de crescimento das plantas. Em campo, foram comparados os seguintes fatores e tratamentos: três condições de competição (ausência de plantas concorrentes; presença de plantas dos cultivares de soja BRS 205 ou Cobb); e quatro cultivares reagentes de soja à competição (IAS 5, BR-16, CD 205 e Fepagro RS-10). Cultivares de soja apresentaram variações na velocidade de emergência e de crescimento inicial de plantas. A presença de plantas concorrentes, independentemente das características próprias, afetou a ramificação da soja. Os cultivares Fepagro RS-10 e BR-16 apresentaram rápido crescimento durante a fase inicial de desenvolvimento; CD 205, ao contrário, mostrou lento crescimento nesta fase. Cultivares de soja de ciclo precoce cobriram com mais rapidez o solo durante os primeiros 45 dias do que os tardios.

Cotton Tolerance to Hoplolaimus columbus and Impact on Population Densities.

Glyphosate-tolerant transgenic-cotton cultivars were evaluated for tolerance to Hoplolaimus columbus in field experiments conducted from 2001 to 2003. The studies were arranged in a split-plot design that included treatment with 1,3-dichloropropene at 42 liter/ha to establish fumigated versus nonfumigated subplots with cultivars as whole plots. Cotton cultivars were divided by relative maturity into two separate but adjacent experiments in order to facilitate cotton defoliation, with 10 early-maturity and 5 late-maturity cultivars. Fumigation was effective in suppressing H. columbus population densities and increased cotton lint yield. The cultivar-fumigation interaction was significant for early-season cotton cultivars but not for late-season cultivars. A tolerance index ([yield of nontreated/yield of treated] × 100) was used to compare cultivar differences. Both groups of cultivars expressed significant levels of tolerance to H. columbus, but late-season cultivars tended to yield more than early-season cultivars in infested fields.

Content of low molecular weight carbohydrates in vining peas ( Pisum sativum) related to harvest time, size and brine grade

Knowledge of how the content of low molecular weight carbohydrates (LMWC), including the raffinose family oligosaccharides (RFO; raffinose, stachyose and verbascose), changes in unripe peas ( Pisum sativum) around harvest time, is today limited. An early and a late maturing cultivar of peas were harvested with 24 h of each other on seven different occasions, of which three were chosen for this study. The pea samples were divided into three groups by size and brine grading, and then analysed with regard to the content of low molecular weight carbohydrates. The content of raffinose and stachyose increased in all groups during a period of 5 days. Peas that sank (sinkers) in the brine grading test had a higher content of raffinose and stachyose and a lower content of sucrose than floating peas, indicating that sinkers have reached a greater degree of maturation. The content of verbascose remained the same or decreased during the study period. In conclusion, the date of harvesting green peas for freezing affects the contents of RFO.

Effects of Planting Date on the Growth and Yield of Two Potato Cultivars Grown from Microtubersand Conventional Seed Tubers

This study clarified the effect of planting date on the growth and yield of potato (Solanum tuberosum L.) plants grown from conventional seed tubers (CT) and microtubers (MT). CT of about 50 g and MT of 1 to 3 g of early (Kitaakari) and late (Norin 1) maturity cultivars were planted at Hokkaido University, Sapporo, Japan, on May 13, June 4 and June 25, and their growth and yields were investigated. The linear increase in leaf area index started later, but thereafter was higher in MT plants than in CT plants, irrespective of cultivar and planting date. Tuber formation was later in MT plants than in CT plants of both cultivars, but this difference was smaller on the last planting date. The linear increase in tuber dry weight started later in MT plants than in CT plants, but the rate of increase was similar in MT and CT plants of both cultivars and on all planting dates. Delaying the date of planting reduced the tuber yield, mainly because of the shortening growing period in MT and CT plants. The reduction in tuber yield and growing period was greater for the late cultivar Norin 1 compared with the early cultivar Kitaakari of CT and MT plants. Despite the climatic variations among the planting dates, MT plants yielded 71 to 90% of tuber fresh weight relative to CT plants, suggesting that MT are a good alternative as propagules for potato cultivation in countries where seed production is difficult.

추파용 호밀 품종의 파종기에 따른 Feekes scale에 의한 생장발달 분석

본 연구는 파종기가 다른 추파호밀의 Feekes scale에 의한 생장발달을 분석하기 위하여 수행하였다. 시험배치는 10처리 3반복의 분할구배치로 주구에는 9월 30일과 10월 15일의 파종시기를, 세구로는 'Kodiak', 'Koolgrager', 'Danko', 'Homil22', 'Olhomil' 품종을 두었다. 초장은 조기파종이 만기파종보다 높았으며, 공시품종간에는 조생품종이 가장 높았다. 분얼경수는 조기파종시에 48.0개로 만기파종시의 24.3개보다 높았으며, 공시품종간에는 만생품종이 다른 품종보다 높게 나타났다. 생장발달 분석에 있어서 조기파종이 만기파종보다 3일 빨랐다. 조기파종시에는 조생품종인 'Olhomil'이 만생품종인 'Danko' 보다 숙기가 빨랐으며, 만기파종시에도 조생품종인 'Olhomil' 및 'Koolgrager'가 빠른 숙기를 보여주었다. 그러므로 시험에서 얻은 결론은 추파용 호밀의 생장과 발달단계를 Feekes scale로 비교한 결과 'Olhomil' 및 'Koolgrazer'는 조생종,'Homil22'는 중생종 그리고 'Kodiak' 및 'Danko'는 만생종으로 분류가 가능했다. This experiment was carried out to assess the growth and development of five rye(Secale cereale L.) cultivars based on the Feekes scale in relation to sowing date at the Experimental Livestock Farm, Seoul National University(SNU), Suwon from 30 September 2001 to 4 May 2002. The experiment was conducted in split plot design with three replications. The main plots consisted of two sowing date such as early(30 September) and late(15 October). The subplots consisted of rye cultivars of five different maturity groups such as 'Kodiak', 'Koolgrazer', 'Danko', 'Homil22' and 'Olhomil'. The plant height of early sowing rye cultivars was higher than that of late one. Among the rye cultivars tested, plant heights of early maturing cultivars were higher than those of the other cultivars. The tiller number at early sowing(48.0) was higher than that of late(24.3), however, late maturing cultivars were higher than those of the other cultivars among the rye cultivars tested. Growth and development in the early sowing were generally three days earlier than those of late sowing cultivars. Growth and development in 'Olhomil' rye cultivars was earlier than 'Danko' rye cultivars when sown in early, but 'Olhomil' and 'Koolgrazer' rye cultivars showed an early maturity than 'Danko' rye when sown in late. Therefore, the developmental stages of winter rye cultivars could be categorised the following maturity; 'Olhomil' and 'Koolgrazer' are early in maturity, 'Homil22' is medium, and 'Kodiak' and 'Danko' are late in maturity.