TITLE:
Effect of Water Stress on the Growth and Development of Amaranthus spinosus, Leptochloa chinensis, and Rice
AUTHORS:
Bhagirath S. Chauhan, Seth B. Abugho
KEYWORDS:
Biomass; Soil Moisture; Weed; Rainfed; Drought
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.4 No.5,
May
29,
2013
ABSTRACT: Drought is the most important abiotic
constraint in rainfed rice systems. In these systems, Amaranthus spinosus and Leptochloa chinensis are the dominant weed
species, which may reduce the available water to rice by competition and cause
water stress in the crop. Two studies were conducted in a greenhouse to evaluate
the growth response of A. spinosus and rice and L. chinensis and rice to water stress.
The water stress treatments were 12.5%, 25%, 50%, 75%, and 100% of field
capacity and the plants were grown until weed maturity (i.e., 63 days from seeding). Rice plants did not survive at 12.5% and 25% of field
capacity, but both weed species survived in all the treatments. Both weed
species produced a significant number of tillers/branches and leaves even at
the lowest soil water content. The maximum amount of total shoot biomass produced
by weed plants was 2.5 to 3 times more than that of rice plants. The soil water
content to achieve 50% of the maximum aboveground biomass was 47%-50% of field
capacity for rice, whereas it was 39% and 31% of field capacity for A. spinosus and L. chinensis, respectively. A.
spinosus plants responded to increasing water stress with increased leaf
weight ratio, whereas the leaf weight ratio of L. chinensis decreased with increases in water stress. The ability
of A. spinosus and L. chinensis to produce shoot biomass
under water-stressed conditions suggests that weed management strategies are
needed that can minimize weed survival in water-limited environments. These
strategies may include the use of weed-competitive and drought-tolerant
cultivars, high seeding rates, and optimum timing of fertilizers.