Heat Injury during Early Floral Bud Development in Cowpea

Abstract

Heat stress during the vegetative and early reproductive stages induces floral bud abortion in cowpea [Vigna unguiculata (L.) Walp.] and several other crop species growing under long days, and can substantially reduce productivity. The objective of this study was to determine whether there is a specific developmental stage when heat stress causes abortion of floral buds. Cowpea plants were grown in four reach‐in growth chambers under either metal halide‐based (MH) or fluorescent‐based (FL) lighting systems with 14‐h photoperiod and thermoperiod. Heat injury to floral bud development was quantified as floral bud suppression; the percentage of peduncles on the first five reproductive nodes that did not produce at least one flower. In all cases, floral buds were initiated on these nodes. Light quality influenced plant responses, but similar responses to temperature were obtained when red/far red ratios were 1.3 for the MH system and 1.6 for the FL system. High night temperature (30 °C) caused complete suppression of floral buds, whereas development was normal at a night temperature of 20 °C. Transfer and heat‐pulse experiments demonstrated that plants were not sensitive to high night temperature at a particular stage of development but that the duration of heat experience may be critical for the suppression of floral bud development. Two weeks or more of consecutive or interrupted hot nights during the first 4 wk after germination caused complete suppression of the development of the first five floral buds on the main stem. Mechanisms for the effects of heat stress on floral bud development are discussed.

Analysis of differential gene expression during floral bud abortion in radish (Raphanus sativus L.)

“…However, only a few studies have been conducted so far regarding the mechanism of FBA, and most of these studies have only focused on the effects of exogenous hormones and environmental stress on FBA (Ahmed and Hall, 1993;Bosac et al, 1994;Mouhouche et al, 1998;Krupnick et al, 2000;Warner and Erwin, 2005). Only a few studies have investigated FBA at the molecular level, such as gene expression patterns (Jia and Zhang, 2008;Zhang et al, 2010).…”

“…FBA is a widespread phenomenon in plant reproduction and evolution, having been observed in Cucurbita texana (Krupnick et al, 2000), dwarf bean (Mouhouche et al, 1998), cowpea (Ahmed and Hall, 1993), rape (Bosac et al, 1994), Chinese cabbage (Zhang et al, 2010), radish (Liu et al, 2008;Jia and Zhang, 2008), and the model plant Arabidopsis thaliana (Warner and Erwin, 2005). FBA is most commonly thought to result from abiotic stress.…”

“…Exogenous ethylene can induce C. texana to produce more female flowers and experience greater bud abortion in late developmental stages (Krupnick et al, 2000). Heat stress during vegetative and early reproductive stages induces FBA in the cowpea (Ahmed and Hall, 1993). Drought treatment increases the bud abortion rate of dwarf beans from 50 to 70% (Mouhouche et al, 1998).…”

Effects of High Night Temperature on Crop Physiology and Productivity: Plant Growth Regulators Provide a Management Option

“…Warrag & Hall (1984) reported that HNT induced male sterility and excessive floral abscissions in cowpea, whereas high day temperature had no adverse effect. The HNT can decrease crop yields by decreasing crop growth duration, suppressing floral bud development and decreasing pollen production and viability (Ahmed & Hall, 1993;Mohammed & Tarpley, 2009a;Prasad et al, 1999;Prasad et al, 2006). Increase in NT from 27 o C to 32 o C decreased crop growth duration by 2 days, as indicated by emergence of 1 st panicle, in rice (Fig.…”

Breeding Cowpea for Future Climates

“…Suppression of floral buds under long days occurred under hot nights but was greater under the combination of hot nights and very hot days (Dow El-Madina and ). Transfer and heat-pulse experiments demonstrated that plants did not have a particular stage of development where they were very sensitive to high night temperature but that the duration of heat experience may be critical for the suppression of floral bud development (Ahmed and Hall 1993). Two weeks or more of consecutive or interrupted hot nights during the first four weeks after germination caused complete suppression of the development of the first five floral buds on the main stem (Ahmed and Hall 1993).…”