Abstract
Abstract Context Drought and extreme heat at flowering are common stresses limiting the yield of summer crops. Adaptation to these stresses could be increased by sowing summer crops early in late winter or early spring, to avoid overlap of drought and heat with critical crop stages around flowering. Though little is known about the effects of cold weather on root growth, water use and final grain yield in sorghum. Objective This study aims to explore the effects of cold conditions in early sowing sorghum on crop and root growth and function (i.e., water use), and final grain yield. Methods Two years of field experiments were conducted in the Darling and Eastern Downs region of Qld, Australia. Each trial consisted of three times of sowing (late winter, spring, and summer), two levels of irrigation (i.e., rainfed and supplementary irrigated), four plant population densities (3, 6, 9 and 12 pl m −2 ), and six commercial sorghum hybrids. Roots and shoots were sampled at the flag leaf stage on three times of sowing, two levels of irrigation, and three replications, for a single hybrid and a single plant population density (9 pl m −2 ). Crop water use and functional root traits were derived from consecutive electromagnetic induction (EMI) surveys around flowering. At maturity crop biomass, yield and yield components were determined across all treatments. Results The combinations of seasons, times of sowing and levels of irrigation created large variations in growth conditions that affected the growth and production of the crops. Early sowing increased yield by transferring water use from vegetative to reproductive stages and increasing grain numbers in tillers. Cold temperatures in the early sowing times tended to produce smaller crops with smaller rooting systems, smaller root-to-shoot ratios, and larger average root diameters. Total root length and root length density increased with increasing pre-flowering mean air temperatures up to 20 °C. Linear relationships were observed between an EMI derived index of root activity and the empirically determined values of root length density (cm cm −3 ) at flowering. Conclusions Sowing sorghum, a summer crop, early in late winter or spring transferred water use from vegetative stages to flowering and post-flowering stages increasing crop water use later in the season. Root length and root length density were reduced by pre-flowering mean temperatures lower than 20 °C, indicating a need to increase cold tolerance for early sowing. The higher grain numbers in early sown crops were related to higher grain numbers in tillers. The EMI derived index of root activity has a potential in the development of high throughput root phenotyping applications.
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Claims 14
Claim · model-written summary
Early sowing increased sorghum yield.
SorghumNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Early sowing increased yield”
t0“early sowing sorghum”
Claim · model-written summary
Early sowing shifted water use from vegetative to reproductive stages.
- Organ / stage
- vegetative to reproductive stagese0
- Treatment
- Early sowinge0
- Outcome
- water usee0
- Direction
- transferringe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Early sowing increased yield by transferring water use from vegetative to reproductive stages”
t0“early sowing sorghum”
Claim · model-written summary
Early sowing increased grain numbers in tillers.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Early sowing increased yield by transferring water use from vegetative to reproductive stages and increasing grain numbers in tillers”
t0“early sowing sorghum”
Claim · model-written summary
Cold early sowing conditions tended to produce smaller crops and rooting systems.
- Outcome
- smaller crops with smaller rooting systemse0
- Direction
- smallere0
- Setting
- Cold temperatures in the early sowing timese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cold temperatures in the early sowing times tended to produce smaller crops with smaller rooting systems”
t0“early sowing sorghum”
Claim · model-written summary
Cold early sowing conditions tended to reduce root-to-shoot ratios.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cold temperatures in the early sowing times tended to produce smaller crops with smaller rooting systems, smaller root-to-shoot ratios”
t0“early sowing sorghum”
Claim · model-written summary
Cold early sowing conditions tended to increase average root diameters.
- Outcome
- average root diameterse0
- Direction
- largere0
- Setting
- Cold temperatures in the early sowing timese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cold temperatures in the early sowing times tended to produce smaller crops with smaller rooting systems, smaller root-to-shoot ratios, and larger average root diameters”
t0“early sowing sorghum”
Claim · model-written summary
Total root length increased with pre-flowering mean air temperature up to 20 °C.
- Outcome
- Total root lengthe0
- Direction
- increasede0
- Qualifier
- up to 20 °Ce0
- Setting
- pre-flowering mean air temperaturese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total root length and root length density increased with increasing pre-flowering mean air temperatures up to 20 °C”
t0“early sowing sorghum”
Claim · model-written summary
Root length density increased with pre-flowering mean air temperature up to 20 °C.
- Outcome
- root length densitye0
- Direction
- increasede0
- Qualifier
- up to 20 °Ce0
- Setting
- pre-flowering mean air temperaturese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total root length and root length density increased with increasing pre-flowering mean air temperatures up to 20 °C”
t0“early sowing sorghum”
Claim · model-written summary
The EMI root activity index was linearly related to measured root length density at flowering.
- Organ / stage
- floweringe0
- Outcome
- Linear relationshipse0
- Comparator
- empirically determined values of root length densitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Linear relationships were observed between an EMI derived index of root activity and the empirically determined values of root length density (cm cm −3 ) at flowering”
t0“early sowing sorghum”
Claim · model-written summary
Early sowing increased water use during flowering and later stages.
- Organ / stage
- flowering and post-flowering stagese0
- Treatment
- early in late winter or springe0
- Outcome
- crop water use later in the seasone0
- Direction
- increasinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sowing sorghum, a summer crop, early in late winter or spring transferred water use from vegetative stages to flowering and post-flowering stages increasing crop water use later in the season”
Claim · model-written summary
Pre-flowering mean temperatures below 20 °C reduced root length.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Root length and root length density were reduced by pre-flowering mean temperatures lower than 20 °C”
t0“early sowing sorghum”
Claim · model-written summary
Pre-flowering mean temperatures below 20 °C reduced root length density.
- Outcome
- root length densitye0
- Direction
- reducede0
- Setting
- pre-flowering mean temperatures lower than 20 °Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Root length and root length density were reduced by pre-flowering mean temperatures lower than 20 °C”
t0“early sowing sorghum”
Claim · model-written summary
Higher grain numbers in early-sown crops were related to higher grain numbers in tillers.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The higher grain numbers in early sown crops were related to higher grain numbers in tillers”
t0“early sowing sorghum”
Claim · model-written summary
The EMI root activity index has potential for high-throughput root phenotyping.
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The EMI derived index of root activity has a potential in the development of high throughput root phenotyping applications”
t0“early sowing sorghum”
The same questions in other papers
sowing time · yield · SorghumPositive and negative results
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See all 71 papers →sowing time · physiology: water · SorghumResults agree
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