Number Of New Cultivars Research Articles

Micropropagation of Minor Fruit Crops of India: A Review

Micro-propagation refers to the technique of in vitro multiplication of plants in a short duration using any plant parts (nodes, leaves, flowers, seeds etc.) under aseptic conditions. It is advantageous over vegetative propagation and its application in horticultural aspects. It is well-proven method of surplus production of elite identical plants in a controlled environment which are uniform, stable, disease-free, true-to-type and are independent of any seasonal restrictions or limitations. India is homeland to diverse of significant but minor fruit crops such as Indian gooseberry, (Emblica officinalis Gaertn.), Karonda (Carissa carandas L.), Bael (Aegle marmelos Corr.), Jamun (Syzygium cuminii L.), Jackfruit (Artocarpus hetrophylous L.) which bear high nutritional, medicinal, therapeutic values and of great commercial importance (medicinal, food and cosmetics). Due to a paucity of desirable planting materials, the commercial production process for these crops is restricted. Micropropagation has the potential to significantly increase the number of new cultivars or genotypes of such fruit crops. The objective of this review study is to compile existing research work done on the micropropagation of these underutilized fruit crops.

Yield Potential of Machine-Transplanted Rice and Correlation of Crop-Growing Rate during Grain-Filling Stage

Not enough attention has been paid to the comparison in yield performance and N responsiveness between hybrid rice and inbred rice using the large number of new cultivars released after 2000 under machine transplanting. Field experiments were conducted in 2017 and 2018; 48 widely planted rice cultivars included four groups, namely indica hybrids (IHs), japonica inbreds (JIs), indica-japonica hybrids (IJHs), and indica inbreds (IIs) that were transplanted by machine with three nitrogen fertilizer levels (0, 150, 300 kg ha−1). The average yield of the hybrids (IHs, IJHs) was higher than that of JIs or IIs with a higher crop-growing rate (CGR) during the total growth duration, regardless of the N application level; moreover, longer total growth duration was responsible for the higher yield in IJHs than in IHs. The IHs had a large gap yield which mainly came from the genetic improvement in the CGR during the grain-filling stage. The yield gap was relatively small in JIs, and longer growth duration combined with optimal daily mean temperature during the grain-filling stage was the critical factor for high yield. The JIs or IJHs had higher yield under the N300 level, while the response of IHs to nitrogen varied with different cultivars. Cultivars with higher CGR during the grain-filling stage had higher yield under the N300 level. In conclusion, this study suggests that high CGR during the grain-filling stage may be a vital trait for the development of rice with high yield and high N responsiveness at machine transplanting.

Establishing Pollination Requirements in Japanese Plum by Phenological Monitoring, Hand Pollinations, Fluorescence Microscopy and Molecular Genotyping.

The Japanese plum cultivars commonly grown are interspecific hybrids derived from crosses between the original Prunus salicina with other Prunus species. Most hybrids exhibit gametophytic self-incompatibility, which is controlled by a single and highly polymorphic S-locus that contains multiple alleles. Most cultivated hybrids are self-incompatible and need pollen from a compatible donor to fertilize their flowers. Establishing pollination requirements in Japanese plum is becoming increasingly important due to the high number of new cultivars with unknown pollination requirements. In this work, a methodology for the determination of pollination requirements in Japanese plum-type hybrids is described. Self-(in)compatibility is determined by hand-pollinations in both the field and in the laboratory, followed by monitoring pollen tube elongation with fluorescence microscopy, and also monitoring fruit maturation in the field. Selection of pollinizer cultivars is assessed by combining the identification of S-genotypes by PCR analysis with the monitoring of flowering time in the field. Knowing the pollination requirements of cultivars facilitates the selection of cultivars for the design of new orchards and allows the early detection of productivity problems related with pollination deficiency in established orchards.

Determination of Self- and Inter-(in)compatibility Relationships in Apricot Combining Hand-Pollination, Microscopy and Genetic Analyses.

Self-incompatibility in Rosaceae is determined by a Gametophytic Self-Incompatibility System (GSI) that is mainly controlled by the multiallelic locus S. In apricot, the determination of self- and inter-(in)compatibility relationships is increasingly important, since the release of an important number of new cultivars has resulted in the increase of cultivars with unknown pollination requirements. Here, we describe a methodology that combines the determination of self-(in)compatibility by hand-pollinations and microscopy with the identification of the S-genotype by PCR analysis. For self-(in)compatibility determination, flowers at balloon stage from each cultivar were collected in the field, hand-pollinated in the laboratory, fixed, and stained with aniline blue for the observation of pollen tube behavior under the fluorescence microscopy. For the establishment of incompatibility relationships between cultivars, DNA from each cultivar was extracted from young leaves and S-alleles were identified by PCR. This approach allows establishing incompatibility groups and elucidate incompatibility relationships between cultivars, which provides a valuable information to choose suitable pollinizers in the design of new orchards and to select appropriate parents in breeding programs.

Chilling and Heat Requirements of Temperate Stone Fruit Trees (Prunus sp.)

Stone fruit trees of genus Prunus, like other temperate woody species, need to accumulate a cultivar-specific amount of chilling during endodormancy, and of heat during ecodormancy to flower properly in spring. Knowing the requirements of a cultivar can be critical in determining if it can be adapted to a particular area. Growers can use this information to anticipate the future performance of their orchards and the adaptation of new cultivars to their region. In this work, the available information on chilling- and heat-requirements of almond, apricot, plum, peach, and sweet cherry cultivars is reviewed. We pay special attention to the method used for the determination of breaking dormancy, the method used to quantify chilling and heat temperatures, and the place where experiments were conducted. The results reveal different gaps in the information available, both in the lack of information of cultivars with unknown requirements and in the methodologies used. The main emerging challenges are the standardization of the conditions of each methodology and the search for biological markers for dormancy. These will help to deal with the growing number of new cultivars and the reduction of winter cold in many areas due to global warming.

Self-(in)compatibility, S-RNase allele identification, and selection of pollinizers in new Japanese plum-type cultivars

Japanese plum (Prunus salicina Lindl.) exhibits gametophytic self-incompatibility, a prezygotic reproductive barrier that inhibits the growth of self-pollen tubes in the style, preventing self-fertilization. This reaction of incompatibility is genetically controlled by a multiallelic locus (S). When the S allele in the pollen grain is the same as either of the two S alleles expressed in the pistil, the pollen tube arrests its growth in the style preventing fertilization. Most Japanese plum-type cultivars are self-incompatible and need cross-pollination with compatible cultivars coincident at flowering. In the last years, an important renewal of plant material is taking place, with the introduction of a number of new cultivars from breeding programs of different countries whose objectives include self-compatibility. In South Africa, the ARC Infruitec/Nietvoorbij program has released a series of new cultivars that are being introduced in the main producing countries. However, their adaptability to other areas with different climatic conditions is unknown. In this work, the pollination requirements of twelve cultivars from ARC-Infruitec program is determined, analyzing their behavior in Extremadura (Spain), one of the main producing areas in Europe. For this purpose, for each cultivar, pollen viability has been evaluated through in vitro pollen germination, self(in)compatibility has been determined by the observation of pollen tube growth in self-pollinated flowers under the microscope, and S-alleles have been identified by PCR analysis. The time of flowering has been monitored over five years. The selection of adequate pollinizers were done by assigning the cultivars to their corresponding incompatibility group and comparing their time of flowering. These results can be extrapolated to other areas where these cultivars are newly introduced, although additional data of flowering dates may be required for each zone.

Identification of Self-Incompatibility Alleles by Specific PCR Analysis and S-RNase Sequencing in Apricot.

Self-incompatibility (SI) is one of the most efficient mechanisms to promote out-crossing in plants. However, SI could be a problem for fruit production. An example is apricot (Prunus armeniaca), in which, as in other species of the Rosaceae, SI is determined by an S-RNase-based-Gametophytic Self-Incompatibility (GSI) system. Incompatibility relationships between cultivars can be established by an S-allele genotyping PCR strategy. Until recently, most of the traditional European apricot cultivars were self-compatible but several breeding programs have introduced an increasing number of new cultivars whose pollination requirements are unknown. To fill this gap, we have identified the S-allele of 44 apricot genotypes, of which 43 are reported here for the first time. The identification of Sc in 15 genotypes suggests that those cultivars are self-compatible. In five genotypes, self-(in)compatibility was established by the observation of pollen tube growth in self-pollinated flowers, since PCR analysis could not allowed distinguishing between the Sc and S8 alleles. Self-incompatible genotypes were assigned to their corresponding self-incompatibility groups. The knowledge of incompatibility relationships between apricot cultivars can be a highly valuable tool for the development of future breeding programs by selecting the appropriate parents and for efficient orchard design by planting self-compatible and inter-compatible cultivars.

A Novel Grafting Technique: Tender Twig Grafting (TTG) in Bougainvillea Comm. ex Juss.

Bougainvillea Comm. ex Juss. attracted much attention all over the world due to its ornamental, medicinal and commercial importance. In India, many national research institutes has carried out research for development of different varieties. As a result, a large number of new cultivars have been developed in India. Hybridization, chemical mutagens and tissue culture are common methods of propagation and variety development in Bougainvillea but unfortunately, scientist have not paid much attention towards grafting methods for multicolour Bougainvillea flowering on a single plant. The author have working since many years on multicolour Bougainvillea with Tender Twig Grafting (TTG) with more than 75% success rate. This paper dealt with the practical approach and technique used for the development of ornamentally much demanded multicolor flowering of Bougainvillea on single stock.

Optimizing Production in the New Generation of Apricot Cultivars: Self-incompatibility, S-RNase Allele Identification, and Incompatibility Group Assignment.

Apricot (Prunus armeniaca L.) is a species of the Rosaceae that was originated in Central Asia, from where it entered Europe through Armenia. The release of an increasing number of new cultivars from different breeding programs is resulting in an important renewal of plant material worldwide. Although most traditional apricot cultivars in Europe are self-compatible, the use of self-incompatible cultivars as parental genotypes for breeding purposes is leading to the introduction of a number of new cultivars that behave as self-incompatible. As a consequence, there is an increasing need to interplant those new cultivars with cross-compatible cultivars to ensure fruit set in commercial orchards. However, the pollination requirements of many of these new cultivars are unknown. In this work, we analyze the pollination requirements of a group of 92 apricot cultivars, including traditional and newly-released cultivars from different breeding programs and countries. Self-compatibility was established by the observation of pollen tube behavior in self-pollinated flowers under the microscope. Incompatibility relationships between cultivars were established by the identification of S-alleles by PCR analysis. The self-(in)compatibility of 68 cultivars and the S-RNase genotype of 74 cultivars are reported herein for the first time. Approximately half of the cultivars (47) behaved as self-compatible and the other 45 as self-incompatible. Identification of S-alleles in self-incompatible cultivars allowed allocating them in 11 incompatibility groups, six of them reported here for the first time. The determination of pollination requirements and the incompatibility relationships between cultivars is highly valuable for the appropriate selection of apricot cultivars in commercial orchards and of parental genotypes in breeding programs. The approach described can be transferred to other woody perennial crops with similar problems.

New developments in fiber hemp (Cannabis sativa L.) breeding

Fiber hemp (Cannabis sativa L.) is a sustainable and high yielding industrial crop that can help to meet the high global demand for fibers. Hemp can be grown for fiber, seeds, and/or for dual purpose in a wide range of geographic zones and climates. Currently the main hemp producing regions in the world are China, Europe, and Canada. The number of new cultivars developed for each of these regions has gradually increased, with each region producing its own typical hemp cultivars for different purposes. In this article, the state of the art of fiber hemp breeding programs in Europe, China, and Canada are reviewed. The breeding strategies and tools used in the breeding of hemp cultivars are discussed. We also provide an overview of genetic diversity in hemp for different traits. In addition, the current knowledge of the main breeding goals for fiber hemp, which are an improvement of fiber quality and fiber yield, breeding for specific cannabinoid profiles, control of flowering behavior, male flowering control, and breeding of cultivars for specific environments are evaluated. Lastly, we discuss the inestimable value of next generation technologies to breed new hemp cultivars that are suitable for a biobased economy.

HORTICULTURAL PLANT BREEDING: PAST ACCOMPLISHMENTS, FUTURE DIRECTIONS

HORTICULTURAL PLANT BREEDING: PAST ACCOMPLISHMENTS, FUTURE DIRECTIONS

Aglaonema Cultivars Differ in Resistance to Chilling Temperatures

Abstract Aglaonema is considered one of the most chilling sensitive tropical ornamental foliage plants. However, information on resistance of the ever-increasing number of new cultivars to chilling temperatures is not available. In this study, the chilling response of 12 Aglaonema cultivars was evaluated after exposure to 1.7, 7.2, or 12.8C (35, 45, or 55F) for 24 hours. Results showed that a high degree of genetic variation existed among the cultivars. The cultivar ‘Silver Queen’ demonstrated the greatest sensitivity to chilling with 30% of leaves injured at 12.8C (55F). In contrast, three new cultivars, ‘Emerald Star’, ‘Stars’, and ‘Jewel of India’, were the most resistant, each showing no visible injury at 1.7C (35F). Data also indicated that chilling injury to young leaves was much less pronounced than in either mature or old leaves. Additionally, chilling sensitivity of the cultivars was reduced by pre-exposure to cooler temperatures that were slightly above the chilling range.

Identification of Tall Fescue Cultivars by Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis of Seed Proteins

Tall fescue (Festuca arundinaceae Schreb.) is a cool‐season grass used widely for turf and forage. There is a steady increase in the number of new cultivars of tall fescue that are released through the effort of plant breeders. Most of these cultivars are closely related in pedigree and are similar phenotypically. As a result, identification of tall fescue cultivars has become increasingly cumbersome. The purpose of this study was to develop an electrophoretic procedure which will aid in routine identification of different cultivars of tall fescue. We isolated salt‐soluble globulins and alcohol‐soluble prolamines from nine tall fescue cultivars and resolved them by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE). Salt soluble globulins were very similar in their polypeptide profiles and hence offered little promise in cultivar identification. However, SDS‐PAGE analysis of seed prolamines effectively differentiated the tall fescue cultivars on the basis of presence and absence of unique polypeptides. Subtle differences in the banding patterns of prolamines of closely related cultivars were enhanced by computer assisted densitometer scans. The results of this study indicate that SDS‐PAGE analysis of alcohol‐soluble prolamines can be used as a rapid and reliable method for identification of tall fescue cultivars.

EVALUATION OF NEW HERBAGE CULTIVARS

Some basic principles of herbage cultivar evaluation are outlined. Particular emphasis is placed on the development of procedures which are realistic and relevant to New Zealand farming systems. The importance of regional differences, the zrazing animal; level of soil fertility, management factors, compatibility in mixtures and feeding value are illustrated by examples from different sites within New Zealand and overseas. The high cost involved in the detailed evaluation of the large number of new cultivars now being developed illustrates the need for a continual review oE the effectiveness of current procedures. Suggestions for improvements are made

A HISTORY OF THE INTRODUCTION OF TIMOTHY AND COCKSFOOT INTO ALTERNATE HUSBANDRY IN BRITAIN

The first recorded sowing of American timothy seed in England was in 1743, but the event was otherwise without significance since nothing further was heard of this sowing. The stimulation of interest in timothy began with the sowing by Bartholomew Rocque in the late summer of 1763 of the seed received by the London Society of Arts from America. There was during the first years some confusion regarding its vegetative characters, and also in recognizing the difference between the flowering heads of timothy and those of meadow foxtail (Alopecurus pratensis). A hindrance to progress in the use of timothy arose, without doubt, from lack of experience, and lack of suitable implements to provide the fine, firm, clean seed‐bed required. Midsummer sowing may have contributed to failure, for timothy establishes itself best in a moist soil. Timothy seems to have maintained a rather modest place during the 19th and early 20th centuries. The first real progress was made after 1920 when the agronomic potential of the valuable material among our indigenous populations of grasses was appreciated and developed into a number of new cultivars adapted to current needs.