Periods of Chilling Sensitivity in Germinating Pima Cottonseed¹

Abstract

Seed germination and seedling development are adversely affected in many crops by less than lethal chilling temperatures. Periods of chilling sensitivity have been identified in Upland cotton (Gossypium hirsutum L.) but little work has been reported in Pima cotton (G. barbadense L.). This study was conducted to evaluate the influence of temperature on the degree and timing of chilling susceptibility in germinating Pima cotton and to determine if genetic variability exists. Seed were germinated at 25 or 35 C for 72 hours with one additional 24‐hour chilling exposure of 5, 7, or 10 C at various times during germination. Two periods of chilling sensitivity were noted. The first occurred at the beginning of germination. The second period showed maximum sensitivity between 28 and 32 hours when seed were germinated at 35 C and between 40 and 56 hours when seed were germinated at 25 C. Chilling at 7 C during both sensitive periods delayed emergence from a soil mix. In addition, final emergence was reduced by 26% when seed were chilled at the beginning of germination. Chilling at 5 C caused much more severe damage than chilling at 7 or 10 C. Some experimental lines showed greater resistance to chilling than the commercial cultivar, ‘Pima S‐4.’ Two genetic lines that responded similarly when chilled at 5 C differed significantly when chilled at 7 and 10 C. This suggests that these higher temperatures may be best for evaluating genetic variation and seed treatments to impact chilling resistance.

Respiratory Changes with Chilling Injury of Soybeans

“…have noted that a different sort of chilling injury can be observed following cold treatment after about 2 days of imbibition (3,4). Our data in Figure 2 similarly suggest that in addition to the damage during initial water entry, some damage occurs from chilling at later times.…”

Assessing morphological characteristics of elite cotton lines from different breeding programmes for low temperature and drought tolerance

“…Cole and Christiansen (1975) observed reduced per cent germination of Pima S-4' (G. barbademe L.) than genetic selection M-8 (Gossypium hirsutum L.) over same temperature range after seeds were subjected to different durations of chilling time. Buxton et al (1976) observed similar responses of commercial pima type cultivars to chilling at 5°C, but significant differences at 7 and 10°C and concluded that higher temperatures (>5°C) are more desirable for selection of cold-tolerant genotypes in cotton. Likewise, Christiansen (1968) observed that genotypes of G. hirsutum, L. M-8 and Deltapine 14, showed a similar response to exposure of chilling temperatures during initial hours of imbibition.…”

“…Buxton et al. () observed similar responses of commercial pima type cultivars to chilling at 5°C, but significant differences at 7 and 10°C and concluded that higher temperatures (>5°C) are more desirable for selection of cold‐tolerant genotypes in cotton. Likewise, Christiansen () observed that genotypes of G. hirsutum , L. M‐8 and Deltapine 14, showed a similar response to exposure of chilling temperatures during initial hours of imbibition.…”

“…Seedling emergence and development rate can determine cultivar sensitivity to cool temperatures under controlled conditions and also their relative performance under field conditions (Steiner & Jacobsen, ). Both upland and pima cotton showed reduced germination under chilling temperatures, but the sensitivity to chilling effect declined in both species after cotton seeds were preconditioned to warm temperatures for few hours (Buxton, Sprenger, & Pegelow, ; Christiansen, ). Cole and Christiansen () observed reduced per cent germination of Pima S‐4' ( G. barbademe L.) than genetic selection M‐8 ( Gossypium hirsutum L.) over same temperature range after seeds were subjected to different durations of chilling time.…”

Imbibitional Chilling Injury during Chickpea Germination

“…Once imbibition begins, seeds pass through one or 2 periods of increased sensitivity to chilling injury, depending upon the species (14). The first period coincides with the onset of im bibition and has been observed in many crop seeds (3,10,13), including chickpeas (Table 2). For chickpea seeds, the period most sensitive to chilling injury was the first 30 min of imbi bition.…”