Determinate‐ and Indeterminate‐Type Soybean Cultivar Responses to Pattern, Density, and Planting Date

Abstract

Soybean [Glycine max (L.) Merr.] seed yield is influenced by planting date, pattern, and density of seeding, but cultivars differing in growth habit may vary in response to cultural treatments. Narrow‐row compared to conventional wide‐row plantings have consistently produced higher seed yields in the northern USA, where early maturity groups (MG) and indeterminate (INDT) types are commonly used. Positive responses to narrow rows have been less consistent in the southern USA, where late MG and determinate (DT) cultivars are common. Therefore, we hypothesize that this disparity in seed yield response to narrow‐row culture between the two areas is due to inherent differences in DT‐ and INDT‐type canopies resulting from their growth habits. This study, conducted in Gainesville, FL (29 ° 38′N) in 1984 and 1985, employed ‘Duocrop’ (INDT) and ‘Kirby’ (DT), May and July planting dates, 0.91‐, 0.61‐, and 0.30‐m interrow spacings, and 0.18‐ and 0.08‐m intrarow spacings in a Randomized Complete Block (RCB) design. Node and pod numbers, leaf area index (LAI), crop growth rate (CGR), total biomass, and seed yields were significantly increased (per unit land area) with increasing plant population density (PPD) up to a certain PPD, depending on spatial arrangement. The greatest seed yield of both INDT and DT types was from the May planting, narrow‐row culture (0.30 m), and high PPD, but response to PPD was confounded with squareness (ratio of intra‐ to interrow distance among plants) of planting pattern. High PPD (18 to 42 plants m−2 and high squareness values gave higher seed yields than combinations of lower PPDs and lower squareness values. We conclude that seed yield of both DT and INDT soybean in subtropical latitudes is optimized by May seeding, high PPD (40 plants m−2), and use of square planting patterns as approximated by narrow‐row culture.

Períodos de interferência de plantas daninhas na cultura da cenoura em função do espaçamento entre fileiras

“…Para um mesmo cultivar, a produtividade das culturas geralmente se eleva com o aumento de densidade de plantas até que um ou mais fatores (condições edafoclimáticas ou práticas culturais) se tornem limitantes. Em outras culturas, diversas pesquisas evidenciaram que espaçamentos menores propiciam maiores rendimentos, devido ao aproveitamento mais eficiente da radiação solar, da água e dos nutrientes, além da menor interferência das plantas daninhas, como consequência do fechamento mais rápido do dossel vegetativo (Parvez et al, 1989;Brizuela, 1994;Braz, 1996;Murphy et al, 1996;Casa et al, 2007).…”

Resposta de híbridos simples de milho à redução do espaçamento entre linhas

“…Muitas vezes isto se reflete em incrementos de rendimento de grãos (Karlen & Camp, 1985;Parvez et al, 1989;Murphy et al, 1996), decorrente do aumento da produção fotossintética lí-quida (Bullock et al, 1988). A elevação do rendimento de grãos com a redução do espaçamento entre linhas é atribuída à melhor eficiência na intercepção de radiação e ao decréscimo de competição entre plantas de milho por luz, água e nutrientes, em virtude da distribuição mais eqüidistante das plantas (Johnson et al, 1998).…”

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“…The variation is high if the cause is highly affected by environments. Parvez 6 reported positive correlations between yield and TDM and LAI for both early (May) and late (July) growing seasons but the correlations in the late-planted materials was greater. A seasonal difference in association between yield and branch dry matter of soybean was reported by Board and Harville 8 .…”

“…This association may be an aid to selection aimed at changing the character with which it correlates 1 . Previous research has shown that seed yield of soybean is associated with yield component traits including pods per plant, seeds per pods and seed size 2,3 , with morphological traits such as plant height, total dry matter (TDM), harvest index (HI) 4,5,6 and with physiological traits such as leaf area index (LAI) 7 and crop growth rate (CGR) 8,9 . Soybean breeders sometimes use these traits for indirect selection for yield.…”