Indicator Candidate Traits for Autonomous Fruit Set Ability Under High Temperatures in Capsicum

Cultivar	Species	Number of individuals	Cultivar type
‘Takanotsume’	C. annuum	8	pungent
‘Nikko’	C. annuum	9	pungent
‘Furu-pi-yellow’	C. annuum	11	nonpungent
‘Furu-pi-red’	C. annuum	11	nonpungent
‘Onikis Red’	C. annuum	5	ornamental
‘Colorful Mix’	C. annuum	4	ornamental
‘Uchu Cream Red’	C. annuum	5	ornamental
‘Goshiki Kyokko’	C. annuum	5	ornamental
‘Shima Togarashi’	C. frutescens	4	pungent
‘Bishop's Crown’	C. baccatum	5	ornamental
‘Sy-2’	C. chinense	3	pungent
‘No. 3686’	C. chinense	3	pungent
F₁ hybrid of ‘Sy-2’ × ‘No. 3686’	C. chinense	3	pungent

Air temperatures in the greenhouse during the high-temperature period for screening (A) and the moderate-temperature period (B). Air temperature during confirmation survey in the incubator (C). The line graph and the left Y-axis represent air temperature in the greenhouse. Red, green, and blue lines and circle, triangle, and square points mean highest, average, and lowest temperature on the day, respectively. Bars represent number of hours with temperature above 35 °C

Table 2

Reproductive and vegetative trait parameters under high and moderate temperatures under cultivation in the greenhouse

Cultivar	Pollen number (×10³)			Pollen viability (%)	Pollen germination (%)			Fruit set (%)
Temperature	High	Moderate	H/M	High	High	Moderate	H/M	High	Moderate	H/M
‘Takanotsume’	28.9±11.3 b	19.5±3.1 ac	1.48	7.7±7.9 a	6.5±4.2 ab	7.1±3.3 a	0.91	57.7±20.6 a	32.2±15.7 a	1.79
‘Nikko’	29.9±8.0 b	13.8±.6.6 bcd	2.17	2.8±2.8 a	1.6±1.1 bc	1.4±0.7 a	1.14	18.2±10.3 bc	19.7±14.4 a	0.92
‘Furu-pi-yellow’	55.5±15.7 a	41.4±24.4 a	1.34	0.5±0.7 a	1.7±2.0 bc	2.9±2.0 a	0.61	25.5±17.7 b	36.3±15.8 a	0.70
‘Furu-pi-red’	51.5±13.8 a	38.2±11.5 acd	1.35	7.4±14.2 a	0.6±0.9 c	1.0±0.8 a	0.60	7.7±8.5 c	28.3±9.0 a	0.27
‘Onikis Red’	26.2±5.3 b	-	-	9.6±7.1 a	1.4±1.3 bc	0.5±0.6 a	2.74	9.2±9.5 bc	18.7±14.0 a	0.49
‘Colorful Mix’	35.8±13.5 ab	-	-	8.6±7.7 a	0.4±0.4 bc	0.8±1.1 a	0.57	7.3±4.7 bc	15.4±10.4 a	0.47
‘Uchu Cream Red’	23.0±16.7 b	-	-	14.9±10.6 a	0.4±0.3 bc	1.6±0.8 a	0.25	4.4±6.7 bc	3.5±3.8 a	1.25
‘Goshiki Kyokko’	23.0±9.5 b	-	-	6.3±8.6 a	6.3±4.7 ac	3.2±1.7 a	1.97	52.2±14.2 a	33.3±12.8 a	1.57
‘Shima Togarashi’	21.5±12.6 b	-	-	11.7±7.0 a	12.5±8.0 a	6.9±5.0 a	1.83	1.5±2.9 bc	16.5±13.0 a	0.09
‘Bishop's Crown’	38.4±8.6 ab	45.6±15.0 ab	0.84	2.2±2.6 a	3.8±3.1 bc	16.1±7.0 a	0.24	0.0±0.0 c	20.9±6.8 a	0.00
‘Sy-2’	20.7±9.5 b	9.0±2.7 def	2.30	5.2±1.5 a	3.3±1.6 bc	6.2±3.1 a	0.53	0.0±0.0 bc	-	-
‘No.3686’	10.0±5.3 b	5.0±2.0 f	2.00	6.4±7.2 a	3.5±4.8 bc	6.4±2.8 a	0.55	0.0±0.0 bc	-	-
F₁ hybrid	10.7±4.0 b	4.7±2.7 ef	2.28	15.0±3.4 a	6.1±3.0 ac	5.9±2.9 a	1.02	7.9±8.0 bc	31.2±6.4 a	0.25

Cultivar	Anther length (mm)			Style length (mm)			Anthesis stage			Fv/Fm
Temperature	High	Moderate	H/M	High	Moderate	H/M	High	Moderate	H/M	High	Moderate	H/M
‘Takanotsume’	2.4±0.2 bc	2.8±0.2 ac	0.87	6.6±0.4 a	6.5±0.6 ab	1.01	4.0±0.0 a	3.9±0.4 a	1.03	0.64±0.14 d	0.78±0.02 a	0.82
‘Nikko’	2.5±0.1 b	2.5±0.2 bed	1.00	7.2±0.4 a	7.3±0.1 a	0.99	4.0±0.0 a	4.6±0.0 a	1.00	0.76±0.04 ab	0.72±0.03 a	0.96
‘Furu-pi-yellow’	2.9±0.3 a	2.6±0.3 a	1.12	6.6±0.6 a	5.7±0.4 cde	1.17	3.8±0.7 a	4.0±0.0 a	0.95	0.78±0.01 a	0.77±0.03 a	1.01
‘Furu-pi-red’	2.9±0.3 a	3.1±0.2 acd	0.95	5.7±0.4 h	4.7±0.9 be	1.21	4.0±0.0 a	3.7±0.7 a	1.08	0.77±0.01 a	0.78±0.01 a	0.99
‘Onikis Red’	1.5±0.1 de	1.9±0.5 ef	0.80	4.2±0.6 d	4.3±0.4 ef	0.97	4.0±9.0 a	4.0±0.0 a	1.00	0.65±0.02 bd	0.72±0.09 a	0.90
‘Colorful Mix’	2.0±0.2 cd	2.2±0.4 def	0.92	4.1±0.7 de	4.6±0.3 df	0.90	4.0±0.0 a	4.0±0.0 a	1.00	0.61±002 d	0.78±0.03 a	0.78
‘Uchu Cream Red’	2.4±0.4 bc	2.3±0.2 ce	1.03	4.1±0.6 de	5.4±0.4 cd	0.77	4.0±0.0 a	4.0±0.0 a	1.00	0.63±0.11 cd	0.55±0.17 b	1.15
‘Goshiki Kyokko’	2.1±0.2 c	2.1±0.1 def	1.01	5.6±02 bc	5.2±0.6 cde	1.06	4.0±0.0 a	4.0±0.0 a	1.00	0.72±0.03 ad	0.77±0.03 a	0.94
‘Shima Togarashi’	2.4±0.3 bc	2.3±0.2 ce	1.03	5.3±0.2 bc	5.4±0.4 cde	0.99	2.3±1.0 b	4.0±0.0 a	0.56	0.72±0.05 ad	0.78±0.02 a	0.92
‘Bishop's Crown’	3.0±0.1 a	3.0±0.1 ab	0.99	4.7±0.4 cd	4.5±0.3 df	1.05	2.3±1.2 b	3.9±0.2 a	0.58	0.77±0.02 ab	0.79±0.01 a	0.97
‘Sy-2’	2.1±0.3 bc	2.0±0.3 def	1.07	3.0±0.2 ef	3.5±0.3 f	0.84	2.2±0.7 b	3.7±0.3 a	0.60	0.77±0.03 abc	0.80±0.01 a	0.97
‘No.3686’	1.5±0.1 c	1.5±0.2 f	0.96	1.3±0.3 g	1.4±0.2 g	0.91	2.1±0.1 b	3.4±0.7 a	0.61	0.79±0.00 ab	0.80±0.01 a	0.99
F₁ hybrid	2.0±0.1 ce	1.8±0.5 ef	1.08	2.6±0.1 f	2.0±0.5 g	1.27	4.0±0.0 a	4.0±0.0 a	1.00	0.80±0.01 ab	0.81±0.01 a	0.98

[i] ‘Values are the mean ± SE of each cultivar. Different letters indicate significant differences at the 5% level by ANOVA and Tukey-Kramer test. The sample size of each cultivar was shown in Table 1. Lack of data for ‘Sy-2’ and ‘No. 3686’ concerning the fruit set resulted from the lack of fruiting caused by too low temperature for C. chinense at the end of the moderate season. H/M mean represents the ratio of the values under the high temperature to the moderate temperature

Correlation analysis between traits of *C. annuum* cultivars grown in the greenhouse under high-temperature conditions (A) and moderate-temperature conditions (B). The numbers in the figure show the correlation coefficient (r value) between two traits. Red and blue colors indicate positive and negative correlations, respectively. The deeper the color, the larger the absolute value of the correlation coefficient. The asterisks indicate significant correlations (p < 0.05). Trait observed: FS – fruit set; PG – pollen germination; PV – pollen viability; PN – pollen number; AL – anther length; SL – style length; AS – anthesis stage

Table 3

Percentage of fruit set and pollen germination rate in the confirmation survey on plants grown in a stable high temperature in the incubator

Cultivation place	Cultivar	Fruit set (%)	Pollen germination (%)
Greenhouse	‘Takanotsume’	22.9 ± 6.0^z	17.1 ± 9.7
	‘Peruvian Purple’	0.0 ± 0.0	1.8 ± 0.7
	p-value	0.063^y	0.25^y
Incubator	‘Takanotsume’	16,7	17,3
	‘Murasaki’	2,8	4,0
	p-value	0.15^x	<0.001^y

z values are the means ± SE of each cultivar;

y p-value was calculated by Welch's t-test;

x p-value was calculated by χ-square test

Difference in fruit set under high-temperature conditions of plants grown at the high-temperature period: (A) ‘Takanotsume’ and (B) ‘Peruvian Purple’. The photos were taken on August 30, 2020. The brown ruler shows 30 cm

Germination of pollen of plants grown in the high-temperature incubator (A). Incubation temperatures were 25 °C, 30 °C, 35 °C, and 40 °C. The asterisks indicate 5% level of significance obtained with t-test. (B), (C), (D), and (E) show pollen tube elongations in the pistils of ‘Takanotsume’ pollinated by ‘Takanotsume’ (B) and ‘Takanotsume’ pollinated by ‘Murasaki’ (C). Pollen tube elongations in the pistils of ‘Murasaki’ pollinated by ‘Takanotsume’ (D) and ‘Murasaki’ pollinated by ‘Murasaki’ (E). Scale bars are 1 mm in (B) and (C), and 500 μm in (D) and (E)

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DOI: https://doi.org/10.2478/johr-2022-0017 | Journal eISSN: 2353-3978 (formerly 2300-5009) | Journal ISSN: 2300-5009

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Language: English

Page range: 105 - 116

Submitted on: Jul 1, 2022

Accepted on: Nov 1, 2022

Published on: Jan 5, 2023

Published by: National Institute of Horticultural Research

In partnership with: Paradigm Publishing Services

Keywords:

chili pepper,

fruit set,

greenhouse cultivation,

Related subjects:

Ecology,

© 2023 Akira Yamazaki, Ao Takezawa, Ryohei Nakano, Kazusa Nishimura, Ko Motoki, Munetaka Hosokawa, Tetsuya Nakazaki, published by National Institute of Horticultural Research
This work is licensed under the Creative Commons Attribution 4.0 License.

Volume 30 (2022): Issue 2 (December 2022)

Indicator Candidate Traits for Autonomous Fruit Set Ability Under High Temperatures in Capsicum

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Table 2

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Table 3

Figure 3

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