Thidiazuron (TDZ) and benzylamino purine stimulated shoot proliferation on shoot tip explants of wild apple (Malus domestica Borkh) when incorporated in Murashige and Skoog (MS) medium at concentrations of 1.0–10 μm. Shoot numbers obtained with TDZ were greater than the number produced when using BA in the medium but the shoots were shorter than with BA. Increasing TDZ levels increased shoot proliferation with 10 μm. Apple shoots were successfully rooted on MS medium with 2.0 mg·L–1 NAA and then transferred to a mixture of 1 peat: 1 perlite: 1 soil and acclimatized for potting.
Karim H. Al-Juboory and Jabar H. Al-Niami
Karim H. Al-Juboory and Jabar H. Al-Niami
Leaves of wild apple (Malus domestica Borkh) were excised from in vitro grown shoots transversely cut into halves and plated onto petri dishes containing regeneration media. Cultures were kept in the dark for three weeks before adventitious shoots were observed. Callus from leaf explants produced adventitious shoots after 3 months of in vitro culture. Callus were cultured on Nitsch and Nitsch medium supplemented with a range of BA (0.0–2.0 μm) and NAA (0.0–10 μm). BA at 10 μm combined with NAA (0.5 μm) proved most effective for stimulating shoot proliferation of cultured apple. Plantlets from tissue culture were easily transferred to the greenhouse environment.
Renae E. Moran and Patricia McManus
1-Methylcyclopropene (1-MCP) maintained firmness of `Macoun' apple (Malus ×domestica Borkh.) above 50 N after 90 to 100 days regular air storage when harvested at a starch index of 2.7 to 3.5, and after 50 days when harvested at a starch index past 4.0. Softening of `Macoun' was slowed by 1-MCP in both preclimacteric and climacteric fruit, but for a shorter duration in climacteric fruit. 1-MCP reduced but did not eliminate the occurrence of senescent breakdown. The effect of 1-MCP on coreline browning was inconsistent, reducing its occurrence in 2002 and 2003, but increasing its occurrence in 2001 when fruit were harvested at an advanced maturity.
P. Parchomchuk and M. Meheriuk
Pulsed application of overtree irrigation for evaporative cooling of `Jonagold' apples (Malus domestica Borkh.) reduced visible solar injury by 15.8% (1991) and 9.4% (1992). Maximum fruit surface temperature was reduced by 8.1 °C on a day when the average surface mean of nonsprayed fruit rose to 45.6 °C. Air heated more slowly than the exposed fruit surface and was cooled only 1 to 2 °C by overtree irrigation. Cooling did not affect fruit size, firmness, or redness but reduced soluble solids concentration and increased titratable acidity. Storage breakdown was unaffected in the first year but was reduced by 6.0% in the second year.
C. Chervin, J. Raynal, N. André, A. Bonneau and P. Westercamp
The effects of ethanol vapors, controlled atmosphere (CA) storage, and a combination of both on superficial scald development on `Granny Smith' apples (Malus ×domestica Borkh.) are reported. The major result was that ethanol vapors, applied in cold storage, prevented scald development over a week at 20 °C in apples that had been CA-stored for 4 months, then left for 1 month in cold air storage. Interrupting CA storage aimed to reproduce industry practices when fruit in part of storage rooms has to be sold and the remaining fruit is held in air for later sale. The estimated cost and further development of this method are discussed.
Kentaro Kitahara and Shogo Matsumoto
An S-allele cDNA was cloned from pistils of 'McIntosh' apple (Malus ×domestica Borkh.). The allele, designated Si in Japan and S10 in Europe, is an S-RNase that is very similar (94%) to the S3-RNase at the deduced amino acid sequence level. This allele can be detected by amplification using the polymerase chain reaction (PCR) and specific primers, followed by digestion with restriction enzyme EheI. The S10 allele was discovered in 'Empire', 'Maypole', 'Shinano Red', 'Spencer', and 'Vista Bella'. The S-allele cDNAs sequenced to date are listed with their Japanese and European designations.
G.H. Neilsen, D. Neilsen and F. Peryea
Traditionally, broadcast or foliar fertilizer applications have been used to improve or sustain the nutrition of many irrigated, deciduous fruit tree orchards in western North America. Recent developments, including adoption of low-pressure microirrigation systems and planting at higher densities [especially for apple (Malus domestica Borkh.)], have increased interest in controlled application of fertilizers directly with irrigation (fertigation). Recent fertigation research in western North America is reviewed, emphasizing results from high-density apple orchards. Fertigation and traditional broadcast application methods are examined with respect to mobility of N, P, and K in the soil and response of fruit trees to application of these nutrients.
G.H. Neilsen, P. Parchomchuk, W.D. Wolk and O.L. Lau
Newly planted `Jonagold' and `McIntosh' apple (Malus domestica Borkh.) on M.26 fertigated with Ca(N03)2 showed increased early tree vigor and leaf Ca concentration but decreased leaf Mg and Mn compared to trees fertigated with urea or NH4N03. Fertigation with P increased early tree vigor, leaf and fruit P concentration, and decreased leaf Mn in the first year relative to a single planting hole application of granular P. Increased fruit Ca concentration in `Jonagold' in one year was associated with the use of Ca(N03)2 and fertigation of P. Fruit quality was generally unaffected by the experimental treatments.
C.G. Embree, B.H. Lesser and A.D. Crowe
The 30 apple (Malus domestica Borkh.) rootstock candidates selected for cold hardiness, known as the Kentville Stock Clone (KSC), with `McIntosh' and `Delicious' as scion cultivars, were compared at 11 years of age for tree size, weight, fruit yield, and crop efficiency under field conditions. Trunk cross-section area and tree weight were highly correlated. Tree size was similar for the two cultivars in most cases and ranged in size from semidwarf to very vigorous. Cumulative yield efficiencies varied by nearly two-fold and were not correlated with tree size. The most efficient rootstocks were KSC 28, KSC 7, and KSC 6 in the semidwarf, semivigorous, and vigorous size classifications, respectively.
B.H. Lesser, C.G. Embree and A.D. Crowe
The precocity and productivity of 30 Kentville Stock Clone (KSC) apple (Malus domestica Borkh.) rootstocks, with `McIntosh' and `Delicious' as scion cultivars, were assessed independently of each other using a procedure involving computer-aided fitting of curves to yearly production data. A good fit to the data was obtained after biennial fluctuations in yield were removed by using a weighted, 3-year running average. For all 30 rootstocks combined, `McIntosh' was more precocious and reached a higher level of productivity compared to `Delicious'. There was poor correlation between precocity and productivity.