Tropical and subtropical vegetables (2+1)

Physiological Disorder/Constraints

1. Calyx withering
This disorder occurs between mid-February and mid - April. The affected fruits become reddish brown in colour and lacking in normal luster and thus marketability of fruits is hampered. The affected fruits have much higher calcium and nitrate content than healthy ones.

2. Poor fruit set
In brinjal, four types of flower, according to length of style, are recognized irrespective of the variety namely, long styled, medium styled, pseudo short styled and short styled. Pseudo short and short styled flowers do not normally set fruit but their numbers in a plant are normally higher than long and medium styled of lower which produce fruits.
In brinjal, flowers are normally borne solitarily as well as in clusters. The solitary flowers are mostly long or medium styled whereas mixtures of short styled, pseudo short-styled and medium /long styled flowers are found in the cluster. Obviously ratio of short styled flowers to long/medium styled flowers in cluster in much high (3-4:1). So, fruit set depends on the plant. Natural drop is also a problem in brinjal which may be as high as 50% in medium styled flower and 30% in long styled flower.

Control:
True short styled flowers are actually sterile flowers which cannot be induced to set fruits. However, application of growth substances on pseudo short styled, medium styled and long styled flowers produce higher percentage of fruit set.
1. Spraying the plant with 2 ppm 2, 4,-D at flowering stage when few flower clusters appear.
          2. Spraying with 60 ppm NAA or 500 ppm PCPA (Parachloroacetic acid) at full bloom stage.