Response of garlic (Allium sativum L.) bolting and bulbing to temperature and photoperiod treatments

Abstract

This research was conducted to evaluate the effect of temperature and photoperiod treatments on the bolting and bulb formation of three local garlic cultivars (cvs) in two consecutive years. Naturally vernalized plants of cvs G107, G025 and G064 were transplanted into growth chambers and subjected to various combinations of temperature [T15/10, 15°C/10°C; T20/15, 20°C/15°C and T25/18, 25°C/18°C (day/night)] and photoperiod (L8, 8 h and L14,14 h) treatments. Plant growth, endogenous phytohormone and methyl jasmonate (MeJA) levels, along with the bolting and yield of garlic were evaluated. The experimental results from two consecutive years indicated that higher temperature (20°C or 25°C) and longer photoperiod (14 h) treatments significantly enhanced the garlic bolting, bulbing and cloving with a shorter growth period and a higher bulb weight. Moreover, the endogenous phytohormone and MeJA levels in the test plants were significantly increased by the higher temperature (25°C for the phytohormone level; 20°C for the MeJA level) and longer photoperiod [14 h, except for abscisic acid (ABA), which had the highest level at 8 h] conditions and were decreased by the lowest test temperature (15°C) and shorter photoperiod (8 h, except for ABA) conditions. This response coincided with that of the bulbing index, bolting rate, growth period and bulb weight. In addition, plants treated under the conditions of 20°C/15°C–14 h and 25°C/18°C–14 h produced the highest phytohormone levels (except for ABA) for cvs G025 and G064, respectively, and showed the best bolting and bulbing behavior. It is reasonable to assume that endogenous phytohormone (especially gibberellic acid) and MeJA levels are highly related to garlic bolting and bulbing, which might lead to the different responses of the three studied cultivars to the combination of temperature and photoperiod treatments. Furthermore, cvs G107 and G025 bolt well and have better bulb formation under 20°C–14 h conditions, while the conditions of 25°C–14 h are critical for the bolting and bulbing of cv. G064.

Nitrogen doses and nutritional diagnosis of virus-free garlic

“…In this crop, there were late negative temperatures occurring on September 13th and 14th (-2.5 °C, in both days), coinciding with the phase of differentiation of garlic, and high rainfall precipitation from half to the end of the production cycle of garlic (months from October to December) where the accumulated monthly rainfall was 397, 291, and 218 mm, and the number of days of the months with rainfall being 20, 23, and 21, respectively (Figure 3). As adverse weather conditions, associated with increased N doses applied in the experiments, decreased commercial production and favored the appearance of the plant disturbance false-branching or super-sprouting, in addition to a high incidence of bacteriosis (Wu et al, 2016). These two conditions deteriorate the quality of garlic, and therefore the product is destined for industrial use (Luengo, 1999), and thus classified as non-commercial garlic.…”

“…This physiological disturbance is a process of swelling in the region between the false stem and the true stem, due to the accumulation of reserves at the base of the leaf sheaths, resulting in the formation of a false-bulb (Kim et al, 2013). In addition to excess N, low temperatures and high precipitation also stimulate super-sprouting (Wu et al, 2016).…”

Chemical stress reduces the lateral shoot growth in vernalized garlic

“…This genetic-physiologically caused anomaly is characterized by the early lateral shoot growth of cloves, which not only reduces the culture productivity, but also depreciates the product, compromising its commercial value (Souza & Casali, 1986). In this sense, several factors have been related to the lateral shoot growth in garlic, such as photoperiod (Wu et al, 2015(Wu et al, , 2016, temperature (Wu et al, 2015(Wu et al, , 2016, the cultivar (Resende et al, 2011(Resende et al, , 2013Wu et al, 2016), excessive nitrogen (Marouelli et al, 2002;Trani et al, 2008), irrigation (Marouelli et al, 2002), as well as the regulatory action of gibereline hormones (Vieira et al, 2014;Wu et al, 2016) and jasmonic acid (Wu et al, 2016).…”

Uji Pertumbuhan dan Produksi Tujuh Genotipe Bawang Putih (Allium sativum L.) di Dataran Rendah

“…Hasil penelitian Wu et al (2016) menunjukkan bahwa suhu tinggi dan hari panjang mampu meningkatkan proses pembentukan umbi dengan periode tumbuh yang lebih singkat dan bobot umbi yang lebih tinggi. Tiga kultivar bawang putih yang diuji menghasilkan umbi dengan bobot yang lebih tinggi pada suhu 20 0 C atau 25 0 C dengan panjang hari 14 jam.…”