Effect of plant growth regulators on seed tuber yield in potatoes

Non-Peer ReviewedSeed potato growers seek to maximize the number of desirable sized tubers. This study examined how foliar application of plant growth regulators (PGRs) influence total tuber number (TTN) and drop (25 -50 mm) seed tuber number (STN) in Norland (NOR), Russet Burbank (RB) and Shepody (SH) potatoes under field conditions in 1993 and 1994. In 1993, PGRs, paclobutrazol (PTZ; 300, 450, 600 mg/L), kinetin (KIN; 10 and 20 mg/L), all possible combinations of the above rates of PTZ and KIN and Methyl jasmonate (MJ; 10-7, 10-6, 10-5 and 10-4 M) were applied to NOR and RB potatoes. In 1994, PTZ (300 mg/L), both KIN rates, and the two lowest rates of MJ were eliminated and KIN 20 mg/L or GA3 250 mg/L were applied to some of the PTZ treatments. The potato cultivar, SH was also included. Plants were treated with the PGRs at two growth stages; NOR (1993), RB (1993 and 1994) SH (1994) were treated when tubers were <10 mm or <20 mm in diameter). NOR potatoes (1994) were treated at stolon initiation (no tubers) or early tuber initiation (<8 mm in diameter). PTZ increased STN in RB by 29 to 40% and in SH by 57 to 70 % over the controls. However, PTZ had no effect on TTN and STN in NOR in either year. MJ had no effect on STN in NOR (1993), in RB in either year or in SH in 1994. In 1994, the highest rate of MJ increased STN in NOR by 40% over the control. Application of KIN alone, in combination with PTZ or following PTZ treatment and GA3 to PTZ treated plants had no beneficial effect on either TTN or STN of all three cultivars, compare to the PTZ treatments applied alone. This study suggests that under field conditions PTZ can be used to increase seed tuber production in RB and SH while MJ appears to be effective in NOR potatoes

Calcium amendment and NaCl salt pre-treatment improves salinity tolerance in potato genotypes

Non-Peer ReviewedPre-exposure to low but non-toxic levels of calcium and NaCl salt have been demonstrated to ameliorate the adverse effects of subsequent NaCl stress on plant growth and nutrient uptake. The effect of CaCl2, NaCl and CaCl2 + NaCl on subsequent salt stress tolerance, growth, water status and ion accumulation of four contrasting potato genotypes, 9506, ‘Norland’, ABA-deficient mutant and ABA normal sibling were investigated to provide an additional tool to induce NaCl salt stress tolerance. NaCl pre-treatment was generally the most effective in inducing salt stress resistance reflected by positive response measurements in all genotypes. ‘Norland’ and ‘9506’ enhanced growth up to 70% via root mass under salt stress and expressed elevated water status under NaCl pre-treatment, possibly via Na+ accumulation in the roots. Unlike ‘Norland’, the 9506 genotype also tolerated the presence of Na+ in the shoot. However, NaCl was excluded from the shoot of ‘9506’ after CaCl2 pre-treatment and may indicate a genotype-dependent Ca+2 requirement for Na+ exclusion. In the ABA normal sibling, salt stress resistance was largely regulated by two mechanisms under all pre-treatments: a) shoot Na+ exclusion and root Na+ accumulation; b) enhanced water status which was expressed by an elevation of leaf and shoot water content. This response to pre-treatment was facilitated by: a 40% - 100% increase in root mass, enhanced K+ uptake into the roots, enhanced K+/Na+ ratio in the root and shoots and increased leaf osmotic potential. The ABA-deficient mutant expressed only one mechanism of salt stress resistance in response to pre-treatments in which leaf and shoot water content increased. That the pre-treatments of the ABA-deficient mutant were not able to adequately increase shoot K+ and exclude Na+ from the shoot relative to the ABA normal sibling and other genotypes suggests that ABA is a requirement for this mode of salt stress defence

Temperature adaptation in a changing climate: Nature at risk

Temperature adaptation is a much neglected field in the minds of climate change researchers and policy makers. However, increasing fluctuations in temperature mean that the risk of cold and heat stress will pose an increasing threat to both wild and cultivated plants and animals, with frost injury expected to cause devastating damage to crops on an increasingly large scale. Thus, improving shared knowledge of the biological mechanisms of temperature adaptation in plants and animals will help prevent major losses of crops and genetic resources in the future. This book is the first to focus on the mechanistic similarities between species in their responses to temperature in a multi-organism approach that addresses the challenges and impacts of climate change on temperature adaptation in micro-organisms (including pathogens), invertebrates, economically and scientifically important plants and vertebrates in both terrestrial and marine environments. The book concludes with a focus on the interactions between organisms, exploring common mechanisms in temperature adaptation

Shoot growth of Merlot and Cabernet Sauvignon grapevine varieties

The objective of this work was to evaluate shoot growth of the grapevine varieties Merlot and Cabernet Sauvignon, during 2006/2007, and Cabernet Sauvignon, during 2008/2009, in São Joaquim, SC, Brazil. The experiment was carried out in a commercial vineyard trained on a vertical trellis system. The shoots of the central part of the plants were selected, and the lengths from the base to the apex of 20 shoots per cultivar were evaluated. In 2006/2007, monitoring began at pruning, on 9/15/2006, and ended on 2/6/2007, totalizing 144 days of evaluation. During the 2008/2009 cycle, phenology and shoot growth for 'Cabernet Sauvignon' were assessed from grape development (1/13/2009) (pea-sized grapes) until shoot vegetative growth had ceased. Budburst occurred in the second half of September, and shoot-growth cessation occurred during ripening. Higher growth rates (about 4 cm per day) were observed in pre- and post-flowering, followed by reduction due to the competition for photosynthates for the formation of flowers and bunches. Temperature and photoperiod induce grapevine shoots to cease growth in the highland regions of Santa Catarina State, Brazil