English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Prometryn and metribuzin are the most frequently recommended chemicals for weed control in pigeon pea [Cajanus cajan (L.) Millsp]. These two chemicals were found to be the best preemergence herbicides for weed control (Almodóvar and Vélez-Báez, 1980). Soil adsorption of both herbicides depends on soil properties such as cation exchange capacity, and clay, sand and organic matter content (Liu and Cibes, 1973). Therefore, the response of pigeon pea to these herbicides could be influenced by soil conditions. For example, irrigation regimes influenced phytotoxicity of prometryn to pigeon pea in a San Antón loamy soil but not in Corozal, Coto or Fraternidad clay soils (Liu, 1984). Response of most of the new pigeon pea cultivars to prometryn and metribuzin under local conditions has not been reported, although two new cultivars (Cortada and Guerrero) were recently released (Bosque-Vega et al., 2000a; Bosque-Vega et al., 2000b. A field experiment was conducted at Juana Díaz Substation to evaluate injury and yield responses of five pigeon pea cultivars (including Cortada and Guerrero) to prometryn, metribuzin, and imazethapyr. Seed of cultivars Blanco de Yauco, Cortada, Guerrero, PR 147, and Line 84 were planted 10 April 1996 at a spacing of 30 cm within rows, 91 cm between rows. Experimental units followed a split plot arrangement of a randomized complete block design with five treatments (cultivars), four subplots (three herbicides and the untreated handweeded check), and four replications. Main plots measured 7.3 m wide and 6.1 m long, with eight rows, 0.91 m apart. Subplots consisted of two rows, 6.1 m apart. Prometryn (4.48 kg ai/ha), metribuzin (1.12 kg ai/ha), and imazethapyr (0.14 kg ai/ha) were applied over the soil surface on 11 April 1996. The application rate for each herbicide corresponded to a 2X, where X equals the recommended rate. Rates were increased in order to detect potential crop injury. Crop injury was visually recorded at three and six weeks after planting (WAP), on the basis of a 0 to 10 rating scale, where 0 = no injury and 10 = pigeon pea plants completely affected. For yield determination, fresh pods of pigeon peas were hai'vested from two rows (11.1 m) 8 January 1997. Data were analyzed by using general linear models procedure for a factorial ANOVA, and means were separated by the protected LSD (0.05) test. Emergence, leaf chlorosis, and plant stunting were the symptoms generally observed in pigeon pea seedlings. Cultivar by herbicide treatment interaction was significant for the injury ratings recorded at three WAP and 6 WAP (Table 1). Injury ratings from 0 to 2.0 were considered low phytotoxicity; from 2.1 to 4.0, moderate. The highest injury rating recorded at 3 WAP was in Cortada, followed by PR 147 and Line 84, all treated with metribuzin. Injury symptoms decreased at 6 WAP for all pigeon pea cultivars, except Cortada, which remained with the highest, but moderate, injury when

RESPONSE OF PIGEON PEA CULTIVARS TO PROMETRYN, METRIBUZIN AND IMAZETHAPYR