IN VITRO STUDIES ON MICROGRAFTING TECHNIQUE IN TWO CULTIVARS OF CITRUS TO PRODUCE VIRUS FREE PLANTS

Abstract This study was carried out to assess the potential use and applicability of micrografting technique for the development of virus free nursery in citrus. Some techniques that tend to increase the grafting success were employed. MS media added with 3%, 5% and 7% sugar was used in combination with two grafting methods e.g., inverted-T incision and surface placement in Kinnow mandarin and Succari sweet orange. The grafting was carried out under aseptic conditions by using15 days old etiolated seedlings of rough lemon. Shoot tips (1-2 mm) and 3-leaf primordia (0.3-0.5 mm) were taken from the fresh shoot flushes and grafted in vitro. Higher grafting success of 34.7% was recorded with inverted-T incision than surface placement which gave 26.7% successful micrografts. A total of 21% successful micrografts were achieved at 3% sugar level which increased significantly to 33% with increase in sugar level to 5% in both cultivars. Overall, Kinnow mandarin showed relatively better response in combination with inverted-T incision and produced 33.3% successful micrografts. Succari sweet orange responded maximum with surface placement method and yielded 30.7% successful micrografts

Morphological characterization of pakistani date palm (Phoenix dactylifera l.) genotypes

Twenty Pakistani date palm cultivars from nine different geographical regions were characterized to estimate the polymorphism and possible similarity level. Nineteen morphological traits were explored and subjected to principal component analysis (PCA), cluster analysis (CA) and correlation index. The results brought out important differences in phenotypic characters in all date palm cultivars. Principal component analysis (PCA) indicated that all quantitative traits along with number of wings, frequency of wings, seed surface and seed shape were highly divergent. Similarly cluster analyses (CA) also revealed morphological variability among date palm cultivars and, some relationship and heterogeneity was also observed within cultivars of the same origin

Role of temperature, moisture and Trichoderma species on the survival of Fusarium oxysporum ciceri in the rainfed areas of Pakistan

It has been observed in the present study that when spores of Trichoderma harzianum (Th-2) isolate were applied in the sandy clay loam soil and continuously incubated for 4 months at 25 degrees C and 35 degrees C and at three water potentials, -0.03 MPa, -0.3 MPa and <-50 MPa, it has resulted in significantly reduced (P<0.05), growth of Fusarium oxysporum ciceri (Foc) on branches of chickpea plant. The pathogen population was greatly reduced in the moist soil (43 MPa) when compared with the wet soil (-0.03 MPa) at both temperatures which was indicated by greater colonization and growth of T. harzanum-2 on the branch pieces of chickpea plants. The pathogen was completely eradicated from the chickpea branch pieces, after 6 months at 35 degrees C in the moist soil. In air-dry soil (<-50 MPa), Foc survived in 100% of the branch pieces even after 6 months at both temperatures. When chickpea plant branch pieces having pathogen was sprayed with Th-2 antagonistic isolates of Trichoderma spp., the Th-2 isolate killed the pathogen up to minimum level (10-12%) after 5 months at 35 degrees C in the sandy clay loam soil. It can be concluded that in chickpea growing rainfed areas of Pakistan having sandy clay loam soil, Foc can be controlled by using specific Trichoderma spp., especially in the summer season as after harvest of the crop the temperature increased up and there is rainfall during this period which makes the soil moist. This practice will be able to reduce the inoculum of Foc during this hot period as field remain fallow till next crop is sown in most of the chickpea growing rainfed areas of Pakistan

Assessment of morphological attributes of date palm accessions of diverse agro-ecological origin

Sixteen Pakistani date palm cultivars from diverse origins were characterized morphologically to assess the similarity level, the overall point of polymorphism and important agronomic traits existing in the germplasm present in Pakistan. Forty two qualitative and quantitative features were explored and subjected to multivariate analyses. The results brought out important differences in phenotypic characters in all date palm cultivars. Principal component analysis (PCA) indicated that trunk length and diameter, total number of leaves, rachis length, leaflets length and width, number of leaflets per side, number of pinnae planes, length and grouping of spines were highly divergent. Similarly cluster analyses (CA) also revealed phenotypic diversity among date palm cultivars and, some close association or heterogeneity was also observed within cultivars of the same origin

Genetic Variability and Population Structure of Pakistani Potato Genotypes Using Retrotransposon-Based Markers

Molecular germplasm characterization is essential for gathering information on favorable attributes and varietal improvement. The current study evaluated the genetic divergence and population structure of 80 potato genotypes collected from Punjab, Pakistan, using polymorphic retrotransposon-DNA-based markers (iPBS). A total of 11 iPBS primers generated 787 alleles with a mean value of 8.9 alleles per primer, of which ~95% were polymorphic across the 80 genotypes. Different variation attributes, such as mean expected heterozygosity (H = 0.21), mean unbiased expected heterozygosity (µHe = 0.22), and mean Shannon’s information index (I = 0.32), showed the existence of sufficient genetic diversity in the studied potato genotypes. Analysis of molecular variance (AMOVA) showed that genetic variation within the population was higher (84%) than between populations (16%). A neighbor-joining tree was constructed based on the distance matrices that arranged the 80 genotypes into five distinct groups, and the genotypes FD61-3 and potato 2 had the highest genetic distance. A STRUCTURE analysis corroborated the dendrogram results and distributed the 80 genotypes also into five clusters. Our results determined that retrotransposon-based markers are highly polymorphic and could be used to evaluate genetic diversity between local and exotic potato genotypes. The genotypic data and population structure dissection analysis reported in this study will enhance potato varietal improvement and development

Induced polyploidization in Brassica campestris L. (Brassicaceae)

Present experimental design has been made up to obtain crop with higher ploidy level via synthetic polyploidization. Since ploidy manipulation is generally associated with the obtainment of some increased enviable traits of the crop and also provides them greater adaptability to unfavorable or harsh circumstances as compared to its diploids counterparts. Thus, herein present research autotetraploids of Brassica campestris L. have been lucratively achieved by the application of colchicine. Two methods of treatment were utilized i.e. seed treatment and seedling treatment. No polyploidy could be obtained through seed treatment while seedling treatment responded well towards polyploidy. However, the status of autotetraploidy has been confirmed by cytomorphological investigations of treated plants as against its diploids counterparts. For the purpose, morphological parameters such as increased stomata size, pollen diameter, flower size, reproductive organs whereas reduction in plant height, leaf length, leaf breadth, stomata frequency, number of flowers/inflorescence etc. were appraised. Further, cytological observations were made that had clearly revealed the doubling of genome in the autotetraploids as compared to diploids. Meanwhile, pollen fertility and size of pollen grains were evaluated as well.Разработана экспериментальная схема получения сельскохозяйственных культур с более высокой плодиностью путем искусственной полиплоидизации. Изменение плоидности обычно связано с приобретением некоторых важных признаков у таких культур, а также обеспечивает их более высокую приспособляемость к неблагоприятным или суровым условиям внешней среды по сравнению с диплоидными аналогами. В настоящем исследовании представлено успешное получение автотетраплоидов Brassica campestris L. с помощью колхицина. Для этого применяли два метода обработки – семян и проростков. Никакой полиплоидии не обнаружено при обработке семян, тогда как после обработки проростков полиплоиды были получены. С помощью цитоморфологических исследований подтверждено наличие автотетраплоидности у обработанных растений по сравнению с их диплоидными аналогами. Для этого оценивали такие морфологические параметры, как увеличенные размер устьиц, диаметр пыльцы, размер цветка, репродуктивные органы, а также уменьшенные высота растений, длина листа, ширина листа, частота устьиц, число цветков и соцветий. Более того, в результате цитологических исследований четко установлено удвоение генома у автотетраплоидов по сравнению с диплоидами. Наряду с этим в работе оценивали фертильность пыльцы и величину пыльцевых зерен