A. K. Koul

Prospects of breeding improved garlic in the light of its genetic and breeding systems

SummaryGarlic is an obligate apomict which defies all possibilities of genetic improvement through recombinant breeding. Nevertheless, like other bulbous or tuberous plants garlic has accumulated a lot of variation in many characters. Evidence of hybridity exists even at the chromosomal level. Existence of this natural variation, even in respect of the plant part that is economically important, suggests the possibility of improvement. The prospects of exploiting this variation in the face of apomixis are discussed.

Pollen grain germination inside the anthers of two chasmogamous angiosperms: almond (Prunus amygdalus L. Batsch) and apple (Malus pumila Mill.)

SummaryPollen grain germination inside anthers has so far been known in only eleven chasmogamous angiospermous species. The discovery of this phenomenon in some varieties of Prunus amygdalus (almond) and Malus pumila (apple) is therefore significant. The anomaly appears to be genetically controlled, the gene expression occurring under specific environmental conditions.

Genetic diversity among Plantagos V. Transmission of the additional chromosome in a triplo-4 individual ofPlantago lagopus L.

In crosses betweenP. lagopus trisomic for chromosome 4 and normal disomics the extra chromosome is transmitted to about 1/4 of the progeny through the male side and to over 1/2 on the female side. Among the progeny some non-parental types which include a tetrasomic (2x + 2) and an aneutriploid (3x + 1) were also found. Chromosomal behaviour during their male meiosis is described.

Floral biology of almond (Prunus amygdalus L. Batsch) under cultivation in Kashmir valley

The almonds, cultivated in Kashmir, on the basis of relative time of flowering reveal early-, mid- and late flowering types. The late blooming types hold key to the isolation of lines that can escape the damage of spring-rains. Anther dehiscence and stigma receptivity overlap creating conditions suited to self-pollination which is however obviated by self-incompatibility.

Reproductive biology ofTorilis arvensis (Hudson) Link

Torilis arvensis is an andromonoecious umbellifer which produces hermaphrodite and staminate flowers in the ratio of 1∶0·36. This figure is recorded for the first time among andromonoecious umbellifers. The species practices geitonogamy on account of weak protandry and little visual impact of its umbels.

Impact of polyploidy on flavonoid constitution inNarcissus tazetta L

The data reported demonstrate the impact of polyploidy on plant phenotype and flavonoid constitution inNarcissus tazetta. Polyploidy induces increase in flower size and intensifies flower colour. The response of flavonoid constitution is variable. In some cases, flavonoid architecture does not register any change with the imposition of polyploidy. Whenever it does, the number of flavonoids is either increased or decreased. The probable explanation for such changes has been discussed.

Plant aneuploids : Suggestions for their classification

The paper lists, defines and classifies all types of aneuploids known hitherto. Categorisation has been made on the basis of the alterations of chromosome number and gene content. The change in nomenclature of some aneuploids has been warranted by the fact that some names that are in vogue do not reflect the precise nature of the aneuploid and, are therefore, ambiguous. For these ambiguous terms new names have been proposed.

Pollination mechanism inCoriandrum sativum Linn. (Apiaceae)

Exposed nectar, abundant pollen production, zygomorphic flowers and compact umbels are the contrivances which attract in large numbers a wide variety of insect species to coriander flowers. Some of these visitors carry coriander pollen from one flower/umbel to another and by so doing act as potential pollinators; others are only casual visitors.

Genetic diversity among Plantagos. XIX, Studies on primary trisomics of Plantago lanceolata L.

Trisomics for two chromosomes have been isolated in the progeny of cross between disomic and aneuploid individual in Plantago lanceolata L. The karyotypic analysis and meiotic studies has revealed their primary nature and identification as Triplo-1 and Triplo-4. Attempt has been made to study impact of trisomy on plant phenotype and fertility. Due to the phenotypic plasticity within the species even at disomic level, the morphological variations induced by trisomy do not become vivid.

Genetic diversity among Plantagos VII. Nature of aneuploids in the progeny of aneutriploid x diploid plants ofPlantago lagopus L.

Although half of the progeny of a cross between aneutriploid (3x + 1) and diploid individuals ofP. lagopus are diploids (2n = 12), hybrids with 2n = 14, 15 & 22 also occur. These have been screened for mode of chromosome pairing and phenotype. Data thus raised have been employed for evaluating their status and possible mode of origin.