Methods for modifying flowering time and seed yield in field crops

Abstract

Methods for manipulating yield and generation time of short day plants grown in a field environment are provided. The methods comprise manipulating external signals such as photoperiod in order to increase the per plant seed yield. Also provided are methods for synchronizing the flowering times of plants in different maturity groups.

1 . A method for increasing seed yield in a field-grown plant, the method comprising:
 (a) growing a plant in a field under vegetative growing conditions;   (b) exposing the juvenile plant to a floral induction treatment such that a flowering response is initiated; and   (c) returning the plant to vegetative growing conditions.   
     
     
         2 . The method of  claim 1 , wherein:
 the vegetative growing conditions of one or both of part (a) and (c) comprise the use of artificial lighting;   exposing a plant in a field to vegetative growing conditions comprises growing the plant under long day conditions without artificial lighting;   the plant is a photoperiodic short day plant;   said plant is selected from the group consisting of soybean, cotton, rice, sorghum, maize, sugarcane, tobacco, canola, alfalfa, strawberry, wheat, barley, and tomato;   the floral induction treatment of part (b) further comprises about 11 to about 13 hours of darkness per night;   the floral induction treatment of part (b) is maintained for a period of about 7 to about 28 days;   the floral induction treatment of part (b) is initiated at a growth stage of from about VE to about V4;   the vegetative growing conditions of one or both of part (a) and part (c) further comprise from about 14 to about 18 hours of light per day;   the vegetative growing conditions of one or both of part (a) and part (c) further comprise providing artificial light at an intensity of at least about 2, 5, 10, 15, 25 or 50 μmoles/m·s; or   one or both of part (a) and part (c) comprise providing about 1, about 2, about 3, about 4, or about 5 hours of artificial light per day before sunrise.   
     
     
         3 . The method of  claim 2 , wherein:
 the artificial lighting is provided to the plant before sunrise;   said plant is a soybean plant; or   the artificial light comprises an intensity of less than about 50, 75, 100, 150, 250, 500, or 1,000 μmoles/m·s.   
     
     
         4 - 13 . (canceled) 
     
     
         14 . The method of  claim 1 , comprising growing the plant under conditions that restrict vegetative growth and enhance flowering. 
     
     
         15 . (canceled) 
     
     
         16 . A method for manipulating flowering time in a plurality of field-grown plants, the method comprising:
 (a) initiating growth of a plurality of plants under vegetative growing conditions;   (b) exposing the plants to a floral induction treatment to initiate flowering; and   (c) returning the plants to vegetative growing conditions.   
     
     
         17 . The method of  claim 16 , wherein:
 the vegetative growing conditions of one or both of part (a) and (c) are provided by the use of artificial lighting;   the vegetative growing conditions of one or both of part (a) and part (c) comprise providing to the plant artificial light at an intensity of at least about 2, 5, 10, 15, 25 or 50 μmoles/m·s;   the vegetative growing conditions of one or both of part (a) and part (c) comprise providing to the plant artificial light at an intensity of less than about 50, 75, 100, 150, 250, 500, or 1,000 μmoles/m·s;   the plurality of plants comprises plants of at least two different genotypes;   the plurality of plants comprises a photoperiodic short day plant;   the plurality of plants comprises soybean, cotton, rice, sorghum, maize, sugarcane, tobacco, canola, alfalfa, strawberry, wheat, barley or tomato plants;   the plurality of plants comprises soybean plants;   the floral induction treatment of part (b) comprises about 11 to about 13 hours of darkness per night;   the floral induction treatment of part (b) is maintained for a period of about 7 to about 28 days;   at least one plant is at a growth stage of from about VE to about V4;   the vegetative growing conditions of one or both of part (a) and part (c) comprise from about 14 to about 18 hours of light per day;   one or both of part (a) and part (c) comprise providing about 1, about 2, about 3, about 4, or about 5 hours of artificial light before sunrise;   at least two of said plurality of field-grown plants are planted at differing times.   
     
     
         18 . The method of  claim 17 , wherein the artificial lighting is provided before sunrise. 
     
     
         19 - 21 . (canceled) 
     
     
         22 . The method of claim  21 , wherein the method synchronizes the flowering time of said plants of at least two different genotypes to permit crossing the plants. 
     
     
         23 - 30 . (canceled) 
     
     
         31 . The method of  claim 16 , further comprising growing the plurality of plants under conditions that restrict vegetative growth and enhance flowering. 
     
     
         32 . (canceled) 
     
     
         33 . A method for increasing seed yield in a soybean plant, the method comprising:
 (a) exposing a soybean plant in a field to vegetative growing conditions with the use of artificial lighting;   (b) exposing the plant to a floral induction treatment of 7-28 days in duration to initiate flowering, wherein said floral induction treatment is initiated at a growth stage of from about VE to about V4, and wherein said floral induction treatment comprises about 11 to about 13 hours of darkness per night; and   (c) returning the plant to vegetative growing conditions of 14-60 days in duration, wherein said vegetative growing conditions comprise providing artificial lighting before sunrise to expose the plant to from about 14 to about 18 hours of light per day.   
     
     
         34 . The method of  claim 33 , wherein:
 the artificial lighting comprises an intensity of at least about 2, 5, 10, 15, 25 or 50 μmoles/m·s; or   the artificial lighting comprises an intensity of less than about 50, 75, 100, 150, 250, 500, or 1,000 μmoles/m·s.   
     
     
         35 . (canceled) 
     
     
         36 . A method of growing a plant comprising:
 (a) initiating growth of at least a first plant in a field;   (b) determining the natural photoperiod of the field grown plant;   (c) adjusting the photoperiod to which the field grown plant is exposed with an artificial light source to produce a vegetative growing condition;   (d) growing a plant in a field under vegetative growing conditions to a juvenile stage;   (e) exposing the juvenile plant to a floral induction treatment, such that a flowering response is initiated;   (f) adjusting the photoperiod to which the field grown plant is exposed with an artificial light source to produce a vegetative growing condition; and   (g) growing the plant under vegetative growing conditions.   
     
     
         37 . A method of growing a plant comprising:
 (a) initiating growth of at least a first plant in a field;   (b) determining the natural photoperiod of the field grown plant;   (c) growing the plant under natural photoperiodic conditions to provide a floral induction treatment, such that a flowering response is initiated;   (d) adjusting the photoperiod to which the field grown plant is exposed with an artificial light source to produce a vegetative growth condition; and (e) growing the plant under vegetative growing conditions.   
     
     
         38 . A method of growing a plant comprising:
 (a) initiating growth of at least a first plant in a field;   (b) determining the natural photoperiod of the field grown plant;   (c) growing the plant under vegetative growing conditions;   (d) adjusting the photoperiod to which the field grown plant is exposed to provide a floral induction treatment, such that a flowering response is initiated; and   (e) returning the plant to vegetative growing conditions.