Abstract
A controlled-nutrient (CN) experiment was conducted to test three heterosis hypotheses with reference to tomato yield, and its components, for a set of two inbred lines and their hybrid that had previously exhibited considerable heterosis under field conditions. The CN treatments consisted of periodic applications of differential doses of nutrient solution to plants reared individually in containers filled with vermiculite. Ripe fruit were harvested, counted and weighed over a period of 340 days. The data permitted the partitioning of yield into a closed system of five component variables. Heterosis was not exhibited by yield, nor yield components, at any of the four nutrient levels. Hence the total heterosis phenomenon was classified as nutrient-dependent: heterosis occurring under field conditions, but not under the nutritional restrictions of the CN experiment. Three heterosis hypotheses were examined for their ability to explain all of the nutrient-dependent aspects of the heterosis phenomenon. Hypothesis 1: Heterosis is a consequence of a more efficient hybrid metabolic system in that it can produce more product with equal input. Hypothesis 2: Heterosis is a consequence of the somatic multiplication of additive component traits. Hypothesis 3: Heterosis is a consequence of a faster hybrid growth rate. Although none of the hypotheses are rejected by the field data, the first two are rejected by the CN experimental results. The third hypothesis fits all aspects of the nutrient-dependent heterosis phenomenon remarkably well. It is speculated that the indeterminate pattern of plant development responsible for yield and its components is due to two major gene systems: genes that determine morphogenetic, and genes that determine growth rate manifestations of growth. Under this hypothesis, the CN technique permits separation of the responses due to these two gene systems.
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Claims 5
Claim · model-written summary
Heterosis was not exhibited by tomato yield or yield components at any of the four nutrient levels in the controlled-nutrient experiment.
- Taxon
- tomato
Solanum lycopersicume1 - Outcome
- Heterosis was not exhibited by yield, nor yield componentse0
- Qualifier
- at any of the four nutrient levelse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Heterosis was not exhibited by yield, nor yield components, at any of the four nutrient levels”
e1“tomato yield”
Claim · model-written summary
The total heterosis phenomenon in tomato was classified as nutrient-dependent: present under field conditions but absent under the nutritional restrictions of the controlled-nutrient experiment.
- Taxon
- tomatoSolanum lycopersicume1
- Outcome
- total heterosis phenomenon was classified as nutrient-dependente0
- Setting
- field conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the total heterosis phenomenon was classified as nutrient-dependent: heterosis occurring under field conditions, but not under the nutritional restrictions of the CN experiment”
e1“tomato yield”
Claim · model-written summary
Heterosis hypotheses 1 and 2 were rejected by the controlled-nutrient experimental results.
- Taxon
- tomatoSolanum lycopersicume1
- Outcome
- the first two are rejectede0
- Qualifier
- CN experimental resultse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the first two are rejected by the CN experimental results”
e1“tomato yield”
Claim · model-written summary
The third heterosis hypothesis, a faster hybrid growth rate, fits all aspects of the nutrient-dependent heterosis phenomenon remarkably well.
- Taxon
- tomatoSolanum lycopersicume1
- Outcome
- fits all aspects of the nutrient-dependent heterosis phenomenone0
- Qualifier
- remarkably welle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The third hypothesis fits all aspects of the nutrient-dependent heterosis phenomenon remarkably well”
e1“tomato yield”
Claim · model-written summary
It is speculated that the indeterminate pattern of plant development responsible for yield and its components is due to two major gene systems.
- Taxon
- tomatoSolanum lycopersicume1
- Gene
- two major gene systemse0
- Outcome
- indeterminate pattern of plant development responsible for yield and its componentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the indeterminate pattern of plant development responsible for yield and its components is due to two major gene systems”
e1“tomato yield”