Fertilizer Cultivar Research Articles

Rhizome and stolon development of bermudagrass cultivars in a transition-zone environment

ABSTRACTBermudagrass (Cynodon spp.) is a warm season turfgrass that spreads by stolons and rhizomes. The present study aimed to increase knowledge on development of stolons and rhizomes in fertile (‘LaPaloma’ and ‘Yukon’) and sterile (‘Patriot’ and ‘Tifway’) cultivars of bermudagrass. A plot trial was established in May 2013 in Legnaro, northeastern Italy. Fertile cultivars were seeded while sterile cultivars were established by vegetative plugs. Turf samples were collected from autumn 2013 until summer 2015 on March, July, and October. Total length of stolons and rhizomes was measured and total dry weight was determined. The concentration of starch in stolons and rhizomes in October was also determined. The stolon and rhizome density per unit area, the rhizome specific weight, and the rhizome/stolon length and weight ratios were calculated. Sterile cultivars had higher stolon and rhizome density compared to fertile cultivars for both length. In all cultivars, the production of stolons was favoured over that of rhizomes and rhizomes began to develop more in the second season after establishment. Cultivars did not differ significantly in starch content, indicating no relationship between stolon and rhizome density and carbohydrate reserve accumulations.Abbreviations: LD: length density per unit area; WD: weight density per unit area; SW: specific weight; LR: rhizome-to-stolon length ratio; WR: rhizome-to-stolon weight ratio; TS: total starch per unit area

Improvement of mineral nutrient content of tomato through selection of cultivars and soil fertility

Depleted soil fertility and high-yielding cultivars have been associated with low nutrient contents in vegetables. This study explored if elemental nutrient concentrations in tomato (Lycopersicon esculentum Mill.) can be increased through selection of cultivars and nutritional regimes. Cultivars with different phenotypes of heirloom and modern origins were studied in field experiments in two years. Chemical fertilizer (10-10-10), compost, and an organic fertility regime of soybean meal, bone meal, and potassium sulfate were assessed for their effects on growth and composition of fruits of the cultivars. Differences in nutrient concentrations between modern or heirloom cultivars or among fertility treatments were small or non-significant. Differences among individual cultivars for each element were large with some cultivars having nearly twice the concentrations of nutrients of others and with considerable uniformity in cultivar rankings among the elements. This work suggests that cultivars can be selected for production of nutrient-dense tomatoes.

Effect of different phosphorus fertilizer sources, cultivar and soil type on growth performance of soybean

The objective of the study was to determine the effects of phosphorus fertilizer source, soil type, cultivar and season on the growth of soybean plant. The 3 x 2 x 2 factorial experiment fitted in a complete randomized design was conducted during spring and autumn seasons. The experiment comprised three sources of phosphorus fertilizer which were control, single superphosphate and organic phosphate. The two soil types used were sand clay loam and loam sand soil. The two cultivars used in this study were DM 4670RR and DM 5953RSF. Measured parameters were plant height, number of leaves per plant, chlorophyll content, fresh shoot mass and root length. Soil type had significant effect (P≤0.05) on number of leaves per plant, chlorophyll content index, fresh shoot mass and root length. Soybean planted in sand clay loam had significantly higher leaf number, chlorophyll content, shoot mass and root length than soybean planted in loam sand soil. Interaction of phosphorus source x cultivar x planting season had significant effect (P≤0.05) on soybean plant height, number of leaves per plant and fresh shoot mass. In this study, the growth performance of soybean depended on soil type.

不同育性三角梅品种之间的形态、花粉活力、造访昆虫及黄酮醇含量的比较研究

不同育性三角梅品种之间的形态、花粉活力、造访昆虫及黄酮醇含量的比较研究

English

Common bean (Phaseolus vulgaris L.) is an important food and cash crop in southwest Ethiopia with multiple uses. Productivity of the crop is, however, low at national as well as regional levels, mainly due to low soil fertility. Phosphorus (P) deficiency is particularly important in acid soils of southwest Ethiopia affecting growth and yield of seed legumes in general and that of common beans in particular. Therefore, a field experiment was conducted to assess the response of common bean cultivars to P application on Nitisols of Jimma in 2016 main cropping season. The treatments consisted of three common bean cultivars (Ibbado, Tatu, and Remeda) and four P fertilizer rates (0, 23, 46, and 69 kg P2O5 ha-1). The experiment was laid out in a Randomized Complete Block Design in a factorial arrangement replicated three times. Results indicated that interaction effects of cultivars and P rates significantly (P < 0.01) influenced phonological parameters, growth parameters, dry biomass yield and seed yield. The highest dry biomass yield (5874 kg ha-1) and seed yield (2821 kg ha-1) were obtained from the treatment combination of cultivar Tatu and 69 kg P2O5 ha-1. The P use efficiency parameters (recovery efficiency, agronomic efficiency) were also significantly affected by the interaction effect of cultivar and P application rate. Cultivar Tatu was found to be more P efficient at P rate of 23 kg P2O5 ha-1. In conclusion, the study pointed out that common bean cultivars responded differently to the various P application rates suggesting the possibility of exploiting cultivar differences to combat P deficiency under acidic conditions. Phosphorus at rate of 23 kg ha-1 will be recommendable for P-efficient cultivar based on phosphorus use efficiency parameters. Accordingly, farmer who has no capacity to buy fertilizer cultivar Tatu was recommended to specific soil of study area. However, since the data is only for one season and location repeating the experiment across location may be helpful to validate the results. Key words: Common bean, phosphorus use efficiency, seed yield, and soil acidity.

Relationships between flower position, shoot structure and fertility for the main Tunisian almond cultivar ‘Achaak’

The Tunisian almond cultivar 'Achaak' is the most important in terms of market demand and fruit quality but unfortunately it is commonly considered as a low producing genotype. Some observations have indicated that this may be due to the lack of some major technical growing practices. However no much data is available to give a scientific explanation for this problem. The objective of this study is to analyze the fertility of the flowers of this cultivar according to flower position and to describe its fruiting structures in comparison to the highly fertile Italian cultivar 'Tuono'. Architectural details of three branches on three trees were described and inventoried. Each branch was characterized (age, length and diameter) and their composition was registered (shoots, spurs, flower buds, fruit). There was a clear divergence in the architecture of the two cultivars and this provided information regarding some problems with 'Achaak'. In 'Tuono' a majority of highly fertile flowers and consequently fruits were present on spurs while 'Achaak' bore mainly on lateral or long 1-year-old shoots with the presence of some short shoots that only cropped once. Additionally, this result provided valuable information for improving the productivity of the 'Achaak' cultivar by applying specific tree training systems and orchard management practices.

Bio-Material Analyses of Two Canola Cultivars Applied with Foliar Surfactant

This study explores canola production in the south eastern United States in order to successfully adapt to the market demand for high valued oilseeds. Two primary objectives were established, determining yield response, and oil quality of harvested seed. Two canola cultivars were evaluated for production in a Piedmont soil (Mecklenburg Sandy Clay Loam) at NC A&T State University research farm located in Greensboro, NC (Guilford County). The study was conducted using a split-plot design with the main plot factor cultivar (Virginia and DKW 46-15), and subplot factor fertilizer rate: (N-P2O5-K2O) in (kg/ha) 0-0-0 (T1), 70-28-84 + Soysoap (T2), 14056-168 (T3) and 140-56-168+Soysoap (T4). Canola oil was extracted using a soxhlet apparatus. For both seed and oil yield response, the effects of fertilizer treatment and cultivar were significant influences. Seed and oil yield response was statistically higher for DKW 46-15 compared to the Virginia cultivar. Application of treatment T4 will maximize oil and seed yield compared to treatments T2 & T1 fertilizer treatments. Higher erucic fatty acid concentrations were found in oil originating from Virginia seeds compared to DKW 46-15. Based on yield response and fatty acid composition, DKW 46-15 might better serve the bio-material feedstock supply chain compared to the Virginia cultivar when produced in the piedmont region of North Carolina.

Assessment of organic and conventional soil fertility practices and cultivar selection on mineral nutrient accumulation in field-grown lettuce

ABSTRACTDepleted soil fertility and high-yielding cultivars have been associated with low mineral nutrient contents in vegetables. This study explored if mineral nutrient concentrations of lettuce (Lactuca sativa L.) can be increased though selection of cultivars and management of soil fertility. Cultivars including butterhead, romaine, and loose-leaf phenotypes of heritage and modern origins were studied. Conventional, compost, and organic regimes were assessed. Elements in whole heads were determined. Heritage cultivars had about 7% higher magnesium, sulfur, copper, and iron (Mg, S, Cu, and Fe) concentrations than modern cultivars with no differences occurring for phosphorus, potassium, calcium, sodium, zinc, manganese and boron (P, K, Ca, Na, Zn, Mn, and B). Differences for each element occurred among phenotypes and fertilization but with no consistent trends. Head weight had only minor effects on nutrient concentrations, but total accumulation increased with head size. Some cultivars had nearly twice the accumulation of nutrients as others. This work suggests that cultivars can be selected for production of nutrient-rich lettuce.

Sorghum production systems and constraints, and coping strategies under drought-prone agro-ecologies of Ethiopia

Sorghum is one of the most important cereal crops worldwide after wheat, rice, maize and barley. Examining the present socio-economic conditions of sorghum-producing farmers in different agro-ecologies in Ethiopia is of importance for the design of improvement strategies. The objectives of this study were to evaluate the sorghum production system and patterns, major production constraints and related coping strategies in north-eastern Ethiopia. Twelve sorghum-growing villages in the North Welo, South Welo and Waghemra districts were surveyed. Descriptive statistics and a generalised additive model were used for data analysis. Constraints affecting the productivity of sorghum include moisture stress, insect pests, striga, farmland shortage, poor soil fertility, diseases, and low-yielding local cultivars. Among the constraints, drought at the grain-filling stage was identified as the most important production problem in the target region. The productivity of sorghum was also hindered by the use of local drought-tolerant but low-yielding landraces, because farmers had been forced to abandon high-yielding and late-maturing landrace cultivars because of the frequent occurrence of drought. To enhance sorghum productivity, farmers’ knowledge and practices, and production constraints need to be integrated from the initial stages of breeding and technology development.

Assessment of mineral nutrient concentrations of lettuce in response to cultivar selection and fertilization in greenhouse production

ABSTRACTMineral nutrient contents in vegetable-based foods are a concern in human diets, and depleted soil fertility and high-yielding cultivars are associated with low nutrient contents. This study explored if mineral nutrient concentrations of lettuce (Lactuca sativa L.) can be increased though selection of cultivars and nutritional regimes in greenhouse production. Cultivars including butterhead, romaine, and loose-leaf phenotypes of heritage and modern origins were studied. Hoagland solution, a commercial inorganic fertilizer, and a commercial organic fertilizer were the nutrient regimes. Heritage cultivars had about 10% higher phosphorus, potassium, calcium, magnesium, and zinc (P, K, Ca, Mg, and Zn) concentrations than modern cultivars. Differences in elemental concentrations occurred among phenotypes and nutritional regimes but with no consistent trend among elements for phenotypes or regimes. Some cultivars had twice the concentrations of nutrients of other cultivars. This work suggests that cultivars can be selected for production of mineral nutrient-rich lettuce.

THE SOUTH AFRICAN DECIDUOUS FRUIT INDUSTRY'S APPLE ROOTSTOCK SCENARIO AND CURRENT INITIATIVES

Trials conducted from 1967 in the main producing areas of South Africa confirmed M793 to be the best standard size apple rootstock, while M7 (susceptible to woolly apple aphids (w.a.a.) and suckering) and MM106 (susceptible to Phytophthora) were conditionally recommended as semi-dwarfing rootstocks. The high vigour MM109 is recommended for soils of low fertility and spur type cultivars. At this stage there is an urgent need for further improved, precocious, productive, yield efficient rootstocks. They must also be resistant to w.a.a. and Phytophthora infections, adaptable to various soil types and climates, suitable for high intensive orchards and less labour intensive. Much emphasis has been placed on trials with new generation rootstocks, especially specific selections of the Geneva® series. This article will discuss the situation over the past 10 years by showing trends in rootstock sales from nurseries. Progress with initiatives to improve the apple rootstock situation in South Africa is discussed.

TRAINING SYSTEM AND ROOTSTOCK AFFECT YIELD, FRUIT SIZE, FRUIT QUALITY AND CROP VALUE OF SWEET CHERRY

A 1999 field trial compared ‘Hedelfingen’, ‘Lapins’, and ‘Sweetheart’ cherry cultivars on Gisela 5, (Gi.5), Gisela 6, (Gi.6) and MxM.2 rootstocks each planted in six cherry training systems (Central Leader-336 trees/ha, Spanish Bush-673 trees/ha, Slender Spindle-897 trees/ha, V-997 trees/ha, Marchant-1,035 trees/ha, and Vertical Axis-1,196 trees/ha). A second 2002 trial compared ‘Lapins’ and ‘Regina’ cultivars on Gi.5, Gi.6, Gi.12 and Mazzard seedling rootstocks each planted in four cherry training systems (Quad Axis-598 trees/ha, Spanish Bush-748 trees/ha, Central Leader-748 trees/ha, and Vertical Axis-997 trees/ha). After 11 years tree size in experiment 1 was smallest with Gi.5, intermediate with Gi.6 and largest with MXM.2. In experiment 2 after 8 years, trees on Gi.5 were the smallest, followed by trees on Gi.6, G.12 and Mazzard which were the largest. Trees on all three Gisela stocks were much more precocious than either MXM2 or Mazzard. Cumulative yield after 11 years with experiment 1 or after 8 years with experiment 2 were highest for trees on Gi.5 followed by Gi.12, Gi.6, Mazzard and MXM.2. With the self fertile cultivars, ‘Sweetheart’ and ‘Lapins’, Gi.5 induced excessive production which resulted in small fruit size. However, with the self infertile cultivar, ‘Regina’, Gi.5 was the only rootstock which induced commercially acceptable high yields of large fruit. Although Gi.12 was a vigorous tree, it had much greater precocity and productivity than Mazzard. Average fruit size was largest on Gi.12 and Gi.6, intermediate on MXM.2 or Mazzard and smallest on Gi.5. Among training systems, the Vertical Axis system had the highest cumulative yield per hectare followed by the V, the Slender Spindle, the Spanish Bush, the Quad Axis, the Marchant, and the Central Leader. Cumulative yields largely reflected density. Fruit size was largest with the Central Leader, Quad Axis and Spanish Bush, intermediate with the Slender Spindle and Marchant system and smallest with the V and the Vertical Axis. Fruit soluble solids were highest with the Central Leader and Quad Axis and lowest with the Spanish Bush and the Marchant. Cumulative crop value was highest for the V in experiment 1 and for the Vertical Axis in experiment 2.

Agronomic practices to reduce leaf spotting and Fusarium kernel infections in durum wheat on the Canadian prairies

May, W. E., Fernandez, M. R., Selles, F. and Lafond G. P. 2014. Agronomic practices to reduce leaf spotting and Fusarium kernel infections in durum wheat on the Canadian prairies. Can. J. Plant Sci. 94: 141–152. Fusarium head blight (FHB) has become an important disease of durum wheat [Triticum turgidum L. ssp. durum (Desf.) Husn] in the humid and sub-humid regions of the prairies along with leaf spots, black point and red smudge. Together, they contribute to lower grain yields and grain quality. The study objective was to determine the effect of seeding rate, nitrogen (N) fertilizer rate, fungicidal treatment, and cultivar on disease severity, crop development, grain yield and quality in durum. A four-way factorial design was used with two seeding rates (150 and 300 viable seeds m−2), two N rates (75 and 100% of recommended rate), three cultivars (AC Avonlea, AC Morse and AC Navigator), four fungicide treatments (no application, propiconazole at flag leaf, tebuconazole at anthesis, and propiconazole at flag leaf followed by tebuconazole at anthesis) and three locations (two in Saskatchewan and one in Manitoba) from 2001 to 2003. There were no interactions among fungicide, seeding rate, N fertilizer and cultivar for all measured variables. Foliar fungicide treatments resulted in greater kernel weight, grain yield and test weight than the no-fungicide treatment. The application of tebuconazole at anthesis did not reduce the amount of FDK in the harvested grain. The application of a fungicide increased the percentage of kernels infected by black point from 0.38% to over 0.50% and red smudge from 0.54 to 0.61%. Two fungicide applications increased red smudge to 0.85%. Grain yield increased by 2.4% when the seeding rate was increased from 150 to 300 plants m−2. Increasing N fertilizer rate increased grain yield by 5.2%, protein concentration by 5.4% and hard vitreous kernels (HVK) by 2.6%, but decreased test weight by 0.5%. Cultivar selection had the largest effect on FDK. In conclusion, effects of a fungicide application on durum wheat did not interact with selection of seeding rates, cultivars or N rates used in this study.

Minimizing invasive potential of Miscanthus × giganteus grown for bioenergy: identifying demographic thresholds for population growth and spread

Spatial demographic models offer a powerful tool for quantifying risk of invasive spread by bioenergy crops. Our results suggest that sterile and fertile cultivars of M. × giganteus have markedly different invasive potential and therefore should be considered separately in management and policy decisions. Feral populations of sterile M. × giganteus would need to experience frequent and severe disturbance to pose a significant invasion risk, indicating that they should be grown well away from riparian areas prone to streambank scouring. In contrast, cultivars of M. × giganteus bearing fertile seed may be very difficult, if not impossible, to contain.

Impact of geographical locations on Mentha spicata antibacterial activities

Medicinal plants produce secondary metabolites that are responsible for their therapeutic properties but the presence of these molecules and conversely their activities is affected by environmental factors like geographical location, fertility of cultivar, part used, season and time of collection. The present study is based on the impact of geographical location on the antibacterial activities of Mentha spicata L. The samples of the plant were collected from eight different locations of Khyber Paktoonkhwa (KPK) province of Pakistan, which included districts of Swat, Mardan, Charsada, Swabi, Peshawar, Kohat, Karak and Bannu. The samples were subjected to hydroalcoholic extraction followed by fractionation with n-hexane, chloroform, ethyl acetate and n-butanol in order of increasing polarity so as to separate the metabolites on the basis of their solubility in respective solvents. A broth macrodilution method was utilized to evaluate the minimum inhibitory concentrations (MIC’s) of the samples against six bacteria (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexenari). The results of the study indicated B. subtilis and S. aureus to be the most sensitive bacteria (MIC = 0.06 – 0.125 mg/ml) while the Gram-negative bacteria were having moderate activities (MIC = 0.06 – 0.5 mg/ml). The samples obtained from the higher altitude regions (Swat, Swabi) and fertile cultivars (Charsada, Peshawar, Mardan) were found to be more effective as far as the antibacterial activities are concerned that signify a positive impact of geographical location and richness of land with respect to nutrients. Key words: Mentha spicata, Lamiaceae, antibacterial activity.

Assessing genetic variability in male sterile and low fertile citrus cultivars utilizing simple sequence repeat markers (SSRs)

Understanding phylogenetic relationships and genetic diversity in citrus are important in clarifying genetic relationships, characterizing germplasm and the registration of new cultivars. In this study, the genetic diversity of 28 accessions of citrus including male sterile, sterile, low fertile and fertile cultivars were investigated using eight pairs of simple sequence repeat markers (SSR) markers, which in total, 54 polymorphic alleles with an average of 4.2 alleles per primer were detected. The lowest number of alleles was observed in TAA27, CTT01, CCSM18 and ATC09 loci with only three alleles and the highest number of alleles was observed in TAA15 locus with eight alleles. Polymorphic information content (PIC) values changed from 0.34 (AG14) to 0.90 (CCSM18). Genetic similarities among accessions were calculated according to Jaccard similarity index and used to construct a dendrogram based on the unweighted pair group method using arithmetic averages (UPGMA) which put the 28 samples into four major groups (A, B, C and D). The cultivars of male sterile satsuma mandarin were clustered into group A; those of orange, grapefruit and Page (a complex hybrid) into group B; mandarin cultivars into group C; and lemon Lisbon into group D. Genetic analysis of sterile and low fertile citrus, provide useful information for further breeding programs, collection, preservation and utilization. Key words : Male sterility, genetic diversity, SSR markers, citrus.

Heavy-ion beam-induced sterile mutants of verbena (Verbena*hybrida) with an improved flowering habit

Sterile mutants of Verbenahybrida were isolated at high frequency from nodal cultures of developed plants irradiated with heavy-ion beams. Sixty four in vitro-cultured nodes of fertile cultivars 'Temari Sakura' (FS), 'Temari Coral Pink' (FC) and 'Temari White' (FW) were irradiated with 1 to 10Gy of 14 N-ion beam (1890MeV). Lateral shoot development of FS, FC and FW was not affected by irradiation with up to 10Gy. After open-pollination, shoots with inflorescence forming unenlarged ovaries were selected and propagated several times by cutting. Shoots were grown to flowering and the selection process for isolating stable sterile mutants was carried out by the same method. Finally, one mutant out of 104 FS lateral shoots (5Gy), one mutant out of 115 FC shoots (5Gy) and 3 mutants out of 108 FC shoots (10Gy) were successfully isolated. With the exception of sterility all these mutants showed normal morphology. Two sterile mutants SS and SC, which were isolated from 5Gy-irradiated FS and FC, respectively, were characterized by their flowering habits. These two mutants grew well, had a larger number of inflorescences, and a better longevity compared with their parental cultivars. These results show that heavy-ion beam irradiation is an excellent tool for isolating sterile mutants without alterations in others important traits at a high frequency. In addition, the characterization of SS and SC indicated that they have different sterile phenotypes: male and female gametes of SS are non-functional, in contrast, SC exhibits self- incompatibility, which results in mutants unable to produce seeds.

Homeotic-like modification of stamens to petals is associated with aberrant mitochondrial gene expression in cytoplasmic male sterile OguraBrassica juncea

We have previously reported correction of severe leaf chlorosis in the cytoplasmic male sterile Ogura (also called Ogu) Brassica juncea line carrying Ogura cytoplasm by plastid substitution via protoplast fusion. Two cybrids obtained from the fusion experiment, Og1 and Og2, were green and carried the plastid genome of B. juncea cv. RLM198. While Og1 displayed normal flower morphology comparable to that of its euplasmic B. juncea counterpart except for sterile anthers, Og2 retained homeotic-like floral modification of stamens to petal-like structures and several other floral deformities observed in the chlorotic (Ogu) B. juncea cv. RLM198 (or OgRLM). With respect to the mitochondrial genome, Og1 showed 81% genetic similarity to the fertile cultivar RLM while Og2 showed 93% similarity to OgRLM. In spite of recombination and rearrangements in the mitochondrial genomes in the cybrids, expression patterns of 10 out of 11 mitochondrial genes were similar in all the three CMS lines; the only exception was atp6, whose expression was altered. While Og1 showed normal atp6 transcript similar to that in RLM, in Og2 and OgRLM weak expression of a longer transcript was detected. These results suggest that the homeotic-like changes in floral patterning leading to petaloid stamens in Og2 and OgRLM may be associated with aberrant mitochondrial gene expression.

Characterisation of an environmentally induced genic male sterile line of indica rice (Oryza sativa spp. Indica)

Environmentally induced genic male sterility has been successfully used in a 2-line system to produce hybrid rice, with the potential to further increase yield. Elite sterile lines need to be developed for a target production environment to successfully use this novel male sterility system. In this study, a new male sterile line, B06S, identified by Jiangxi Agricultural University, China, was characterised for its flowering characteristics, male fertility behaviour, and the inheritance of male sterility. Flowering characteristics were observed in a sterility-inducing season in Nanchang, China. Compared with the typical fertile cultivars Gui99 and Zhongfu906, B06S started flowering at about the same time, had a slightly longer plant flowering duration (18 days) and a similar panicle flowering duration (6 days), and took longer (6 days) to reach 90% flowering spikelets. Also, at the day of peak flowering, B06S started flowering about 2 h earlier and had an earlier peak flowering time (10.00 am), and the percentage of spikelets flowering before noon was slightly lower (83.8%). Spikelet flowering of B06S lasted 5 h, which was more than 2 h longer than the existing sterile lines. Although B06S showed similar openness to other typical sterile lines (PA64S and 595S), it had a higher stigma exsertion rate (82.5%), larger stigma area (0.92 mm2), and longer stigma viability (4 days). Both pollen and spikelet were completely sterile for more than 75 consecutive days when the environmental temperature was above 24°C, otherwise they would have been fertile. Fertility was slightly influenced by photoperiod. Increased fertility was induced when photoperiod was shorter than 11 h per day. Genetic analysis using the F2 and BC1 populations of 6 crosses indicated that male sterility of B06S was predominantly controlled by a recessive major gene. B065S can be grown in large quantity in the winter nursery in Hainan Island, China. A number of crosses combinations between B065S and indica cultivars had significantly higher yield than the best widely grown hybrids in Jiangxi and other parts of China with similar climates. The best early maturing (B06S × 458) and late maturing (B06S × Gui99) hybrids had 8.9 and 10.3% higher yield than the best currently used hybrids (Jinyou402 and Jinyiugui99, respectively), and will be released in 2007.

Nitrogen fertilizer optimization and cultivar selection for rice grown near mountainous slopes in Orissa, India

Degradation of the natural resource base has led to decline in crop yields or stagnation that caused food shortages at varying degrees among mountain families. Rice, the major staple food in Asia, is suffering from lack of suitable cultivar and N fertilizer management, when grown near mountainous slopes under rain-fed agro-ecosystem. An investigation through a field experiment and simulation study was conducted at United Nations University, Tokyo to select suitable rice cultivars and N fertilizer level for the rice grown near mountainous slopes in Orissa, India. The field experiment was conducted during wet season (June to November) of 2001 at Kasiadihi village of Dhenkanal district, Orissa, India with eight popular rice cultivars of medium (120–130 d) and long duration (135–150 d) group and four N levels (0, 40, 80 and 120 kg·ha−1). Highest grain yield of 5,680 kg·ha−1 was obtained from cultivar Ranjit of long duration group followed by 4,730 kg·ha−1 from cultivar Mahamaya of medium duration group, across N levels. CERES-Rice model was used to simulated grain yield of these two selected cultivars using historical weather data of the past 18 years (1983–2000). Long duration cultivar Ranjit registered higher yield with lower stability as compared medium duration cultivar Mahamaya over the past 18 years. An optimum N fertilizer level of 80 kg·ha−1 was recommended for rice grown under rain-fed ecosystem near mountainous slopes in Orissa, India to attain optimum yield potential of cultivar.