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  • Author or Editor: N.K. Singh x
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Abstract

The fact that Gustafson (2) and many other workers after him obtained fruit set without pollination by application of auxins, gibberellins or kinins, and the reports of their natural occurrence in a number of fruits suggests that these substances play a crucial role in the fruit setting and development (5, 3, 4). Attempts to induce parthenocarpy in fruits like plum with auxins, gibberellins or kinetin either alone or in combination have given negative results. Similarly, efforts to induce parthenocarpic fruit growth in mango has not been successful (6).

Open Access

Abstract

Sweet cherries (cultivar—‘Lambert’) were kept in a controlled atmosphere (CA) consisting of 10.5 per cent CO2 and 2.5 per cent O2 at 1°C. The sample fruits were taken periodically during the treatment and also after termination of the CA treatment. The concentration of amino acids, tyrosine and α-amino butyric acid; organic acid, malic acid; and total sugars were determined on an ethanolic extract of the fruit pulp. The respiratory CO2 was measured for separate lots of 1.2 to 1.5 kg of fruit.

Fruit stored at higher CO2 concentration had a lower amount of tyrosine, higher amounts of α-amino butyric and malic acids than in fruits stored in the conventional refrigerator at 1°C. The respiratory rate was inhibited, and there was no significant effect on total sugar content.

Open Access

Abstract

Gibberellic acid (GA3) at concn of 10−1, 10−2 m applied on the buds of “on” year ‘Dashehari’ mango tree just before flower bud differentiation, inhibited flowering 95% and 75%, respectively. Concn of 10−3 and 10−4 m inhibited flowering to a much lesser extent, but delayed the emergence of panicles by nearly 2 weeks.

Open Access

A prevailing hypothesis indicates that a decrease in vegetative growth and cessation in floral initiation in strawberry in response to changes in photoperiod and temperature may correlate with hormonally induced changes. We investigated changes in endogenous free polyamines in crowns, flowers, leaves, and fruit of springbearing strawberries (Fragaria xananassa cvs. Chandler and Earliglow) in response to varying temperatures to induce flowering. Spermidine was the prominent free amine in crowns. No marked changes of putrescine, spermidine, and spermine were observed in crowns during the transition from vegetative to reproductive growth in either cultivar. In contrast, high levels of free polyamines were noted in young developing tissues such as the most recently initiated leaves, flower buds, and green fruit. When the putrescine synthesis inhibitor difluoromethylonithine (DFMO, 1 mm) was exogenously applied, levels of putrescine, spermidine, and spermine were altered in crown tissues in greenhouse experiments. These findings indicate that free polyamines may potentially be associated with the stimulation of new growth in springbearing strawberries under the present experimental conditions evaluated.

Free access