fertilizer application should be increased and tree vigor
should be maintained by trimming (pruning), disbudding,
and thinning the fruit. A farm that does not have satisfactory
tree vigor even when fertilizer application is increased may
have problems with drainage or depth of effective soil, and
these factors should be improved. The nitrogen concentration of the fertilizer applied to the chief cherry-producing
district is approximately 100 kg N ha
−1 .
(3) Method of split application of nitrogen
The period from harvest to leaf fall is long. Therefore, it is
important to promote early growth and full (strong) flower
bud formation in the following year. To increase the next
year’s harvest, topdressing is applied immediately after
harvest to restore exhausted trees and maintain leaf color.
We have been investigating the effect of nitrogen fertilizer on tree vigor and fruit quality at the Yamagata Horticultural Experiment Station. We found that, in the case of
highly productive varieties that are prone to reduced tree
vigor, an increased amount of fertilizer topdressing should
be applied after harvest to recover tree vigor, maintain
dark-colored leaves, and increase both yield and production.
The nitrogen utilization rate in trees increases when fertilization is performed earlier, and nitrogen is distributed
mainly in the younger parts of the plant, such as the leaves.
Post-harvest topdressing contributes to the storage of nutrients, including assimilated nutrients. It has been suggested
that sufficient nitrogen absorption in the tree immediately
after harvest is beneficial and allows the effects of fertilization to last longer. For this reason, the amount of topdressing
applied after harvest is typically 20% or more of the annual
fertilizer application amount. However, depending on
specific factors, such as tree vigor or yield, the proportion of
fertilizer that is applied as topdressing may need to be
adjusted.
(4) Application of the whole amount of fertilizer
immediately after harvest
It is possible to maintain tree vigor by increasing the proportion of fertilizer that is applied as topdressing after harvest. Furthermore, labor can be reduced if all the fertilizer is
applied at once after harvest. Therefore, we compared the
conventional fertilizer application method with the
“whole-volume” fertilizer application method in which the
entire amount of fertilizer is applied immediately after harvest for “Satonishiki” cherry. For the whole-volume method,
the soil inorganic nitrogen content increased, leaf color was
maintained (Fig. 6.16), and comparable growth was
observed in the following year. Moreover, the fruit quality
and yield were equal to or better than those produced using
the conventional fertilization method (Table 6.7; Fig. 6.17).
Therefore, the method of applying all the fertilizer at once
after harvest is beneficial in terms of both yield and labor
reduction (Ando and Shiono 2019).
6.3.4 Use of Arbuscular Mycorrhizal Fungi
(1) Arbuscular mycorrhizal fungi
Arbuscular mycorrhizal (AM) fungi belong to the Glomeromycota and form a symbiotic relationship with the roots
of a host plant. Most crop plants are host plants of AM fungi;
these include plants of families of Poaceae, Fabaceae,
Solanaceae, Liliaceae, Cucurbitaceae, Asteraceae, Rosaceae,
and Rutaceae. The fungi receive sugars from the plant and
supply phosphate to the plant. External hyphae extend into
the soil far from the root surface where P is depleted.
Therefore, AM-colonized plants take up more soil phosphate
than non-colonized plants.
Under soil conditions where P is a limiting factor of plant
growth, AM colonization can increase plant growth. External hyphae can connect different host plant species. Growth
improvement of mixed croppings such as that consisting of
Poaceae and Fabaceae is due to a hyphal network of AM
fungi in soil. The growth response of plants to AM colonization is different among crop species and cultivars
(Tawaraya 2003).
(2) Arbuscular mycorrhizal fungi for horticultural
plants
Inoculum of the AM fungus Glomus R-10 (Idemitsu Kosan
Co. Ltd., Tokyo, Japan) was mixed with sterilized soil
(Tawaraya et al. 2012). Seeds of Welsh onion (Allium fistulosum L. cv. Motokura) were sown in paper pots containing the soil. Seedlings were grown in a glasshouse for
58 days. The paper pots were transplanted into plot plants
were harvested 131 days after transplanting.
The shoot length and stem diameter of the inoculated
plants were higher than those of the non-inoculated plants at
soil P concentrations of 300 and 600 mg P 2 O 5 kg
−1 . The
shoot P contents of inoculated plants were also higher than
those of non-inoculated plants at 300 and 600 mg P 2 O 5
kg
−1 . The yield (shoot fresh weight) of non-inoculated plants
was higher at 1000 and 1500 mg P 2 O 5 kg
−1 than at concentrations of 300 and 600 mg P 2 O 5 kg
−1 (Fig. 6.18). The
yield of inoculated plants was not different among the four P
levels. The yield of inoculated plants at 300 mg P 2 O 5 kg
−1
was the same as the yield of non-inoculated plants at
6 Tohoku Region
207
should be maintained by trimming (pruning), disbudding,
and thinning the fruit. A farm that does not have satisfactory
tree vigor even when fertilizer application is increased may
have problems with drainage or depth of effective soil, and
these factors should be improved. The nitrogen concentration of the fertilizer applied to the chief cherry-producing
district is approximately 100 kg N ha
−1 .
(3) Method of split application of nitrogen
The period from harvest to leaf fall is long. Therefore, it is
important to promote early growth and full (strong) flower
bud formation in the following year. To increase the next
year’s harvest, topdressing is applied immediately after
harvest to restore exhausted trees and maintain leaf color.
We have been investigating the effect of nitrogen fertilizer on tree vigor and fruit quality at the Yamagata Horticultural Experiment Station. We found that, in the case of
highly productive varieties that are prone to reduced tree
vigor, an increased amount of fertilizer topdressing should
be applied after harvest to recover tree vigor, maintain
dark-colored leaves, and increase both yield and production.
The nitrogen utilization rate in trees increases when fertilization is performed earlier, and nitrogen is distributed
mainly in the younger parts of the plant, such as the leaves.
Post-harvest topdressing contributes to the storage of nutrients, including assimilated nutrients. It has been suggested
that sufficient nitrogen absorption in the tree immediately
after harvest is beneficial and allows the effects of fertilization to last longer. For this reason, the amount of topdressing
applied after harvest is typically 20% or more of the annual
fertilizer application amount. However, depending on
specific factors, such as tree vigor or yield, the proportion of
fertilizer that is applied as topdressing may need to be
adjusted.
(4) Application of the whole amount of fertilizer
immediately after harvest
It is possible to maintain tree vigor by increasing the proportion of fertilizer that is applied as topdressing after harvest. Furthermore, labor can be reduced if all the fertilizer is
applied at once after harvest. Therefore, we compared the
conventional fertilizer application method with the
“whole-volume” fertilizer application method in which the
entire amount of fertilizer is applied immediately after harvest for “Satonishiki” cherry. For the whole-volume method,
the soil inorganic nitrogen content increased, leaf color was
maintained (Fig. 6.16), and comparable growth was
observed in the following year. Moreover, the fruit quality
and yield were equal to or better than those produced using
the conventional fertilization method (Table 6.7; Fig. 6.17).
Therefore, the method of applying all the fertilizer at once
after harvest is beneficial in terms of both yield and labor
reduction (Ando and Shiono 2019).
6.3.4 Use of Arbuscular Mycorrhizal Fungi
(1) Arbuscular mycorrhizal fungi
Arbuscular mycorrhizal (AM) fungi belong to the Glomeromycota and form a symbiotic relationship with the roots
of a host plant. Most crop plants are host plants of AM fungi;
these include plants of families of Poaceae, Fabaceae,
Solanaceae, Liliaceae, Cucurbitaceae, Asteraceae, Rosaceae,
and Rutaceae. The fungi receive sugars from the plant and
supply phosphate to the plant. External hyphae extend into
the soil far from the root surface where P is depleted.
Therefore, AM-colonized plants take up more soil phosphate
than non-colonized plants.
Under soil conditions where P is a limiting factor of plant
growth, AM colonization can increase plant growth. External hyphae can connect different host plant species. Growth
improvement of mixed croppings such as that consisting of
Poaceae and Fabaceae is due to a hyphal network of AM
fungi in soil. The growth response of plants to AM colonization is different among crop species and cultivars
(Tawaraya 2003).
(2) Arbuscular mycorrhizal fungi for horticultural
plants
Inoculum of the AM fungus Glomus R-10 (Idemitsu Kosan
Co. Ltd., Tokyo, Japan) was mixed with sterilized soil
(Tawaraya et al. 2012). Seeds of Welsh onion (Allium fistulosum L. cv. Motokura) were sown in paper pots containing the soil. Seedlings were grown in a glasshouse for
58 days. The paper pots were transplanted into plot plants
were harvested 131 days after transplanting.
The shoot length and stem diameter of the inoculated
plants were higher than those of the non-inoculated plants at
soil P concentrations of 300 and 600 mg P 2 O 5 kg
−1 . The
shoot P contents of inoculated plants were also higher than
those of non-inoculated plants at 300 and 600 mg P 2 O 5
kg
−1 . The yield (shoot fresh weight) of non-inoculated plants
was higher at 1000 and 1500 mg P 2 O 5 kg
−1 than at concentrations of 300 and 600 mg P 2 O 5 kg
−1 (Fig. 6.18). The
yield of inoculated plants was not different among the four P
levels. The yield of inoculated plants at 300 mg P 2 O 5 kg
−1
was the same as the yield of non-inoculated plants at
6 Tohoku Region
207