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Growth Analysis of Cotton Crops Infested with Spider Mites: II. Partitioning of Dry Matter
Author(s) -
Sadras Víctor O.,
Wilson Lewis J.
Publication year - 1997
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1997.0011183x003700020030x
Subject(s) - biology , spider mite , dry matter , lint , shoot , agronomy , tetranychus urticae , crop , fiber crop , leaf area index , cultivar , malvaceae , yield (engineering) , horticulture , pest analysis , materials science , metallurgy
Foliar pests can affect reproductive allocation in plants. Depending on how spider mites ( Tetranychus urticae Koch) affect dry matter partitioning in cotton ( Gossypium hirsutum L.), yield losses in infested crops could be similar, greater, or lower than expected from shoot growth reduction. In this paper, we analyzed the effects of mite infestations initiated at three stages during the crop cycle on the yield, growth and dry matter partitioning of cotton. Normal‐ and okra‐leaf types, which are known to differ in their responses to mites, were compared in two experiments. Lint yield losses were significant and were greatest for the earliest mite infestations. Reduced shoot dry matter and reduced harvest index (lint yield/shoot dry matter) both contributed to these yield reductions. Yield losses were less severe in the okra‐leaf cultivar than in its normal‐leaf counterpart; this was in part due to a more favorable partitioning to key yield components in the former. In both experiments, reduced lint fraction Lg lint (g seed cotton) −1 ] contributed to the lower harvest index of damaged crops. Reductions in both fruit number per unit shoot dry matter and seed cotton mass per fruit also contributed to reductions in harvest index of damaged crops. Despite the observed reductions in harvest index and some of its components, allometric analysis showed that mites did not affect partitioning to reproductive organs even in the more severely infested treatments. Rather, the low harvest index of miteinfested crops was the result of small plant size. We conclude that mite effects on cotton growth and yield could be modelled by taking into account their primary effect on radiation‐use efficiency and leaf senescence. Explicit modelling of the effects of mites on dry matter partitioning may not be necessary.